jear2012 Abstract The aim of this paper was to analyze the distribution of chironomids (Diptera, Chironomidae), and determine their substrate preferences, from two hydrosystems located in northeastern Algeria: the Kebir-East and the Seybouse wadis. Sixty-five species were recorded in 49 sampling sites distributed along the main courses of the two hydrographic nets and their tributaries. The majority of taxa comprised cosmopolitan species widely distributed along these two hydrosystems. Cricotopus (Cricotopus) bicinctus showed the highest abundance and frequency of occurrence (29.52%) and was widespread in almost all the sampling sites. Species richness ranged from 4 to 23, Shannon diversity between 0.15 and 0.90, Evenness from 0.23 to 1. A cluster analysis was carried out to represent the different groups of sites sharing similar species compo- sition. Agglomerative cluster analysis grouped the sampling sites into four clusters according to the community data. An Indval analysis was then carried out to detect indicator species for each group of the sam- pling sites. Cricotopus (Isocladius) sylvestris was indicator of the first group of the sampling sites. Orthocladius pedestris, Rheocricotopus chalybeatus and C. bicinctus were indicators of the second group, and Polypedilum cultellatum of the third group. The fourth group was not characterized by any species. Indval analysis allowed also to determine species preferences for substrate size: Corynoneura scutellata and Dicrotendipes nervosus emphasized a preference to fine gravel, and Glyptotendipes pallens to fine sand. Introduction Mediterranean wetlands are under tremendous pressure due to numerous factors like demography, human encroachment and climate change (Hollis, 1992; Hulme et al., 2001). Loss of wetland biodiversity can only be mitigated through critical knowledge of threats (Battisti et al., 2008; Gibbs, 2000). Such knowledge is compromised when local biodiversity is not well understood, as is the case of northeastern Algeria which houses a wide spectrum of wetlands, many of interna- tional importance (Samraoui & Samraoui, 2008). Despite their ecolog- ical and biogeographical interests, the aquatic communities of north- eastern Algeria have attracted few systematic studies (Samraoui & Menai, 1999; Samraoui & Corbet, 2000; Annani et al., 2012; Samraoui et al., 2012). The Chironomidae (Diptera) constitute a highly diversified group of aquatic insects frequently occurring in high density in different kinds of ecosystems (Coffman & Ferrington, 1984). The Chironomidae are of great significance in the structure and function of lotic systems due to their great abundance, diversity and occurrence (Cranston, 1995). The larvae of this family are fundamental components in freshwater food webs, occupying different habitats within river basins, with their dis- tribution determined by several factors; among them, substrate size has an important role in the spatial distribution of macroinvertebrate assemblages (Sanseverino & Nessimian, 2001; Brooks et al., 2005). The understanding of the relationship between species and environ- ment is essential; therefore, every assessment will be more accurate if habitat preferences and indicator species are known (Legendre & Legendre, 1998; McGeoch & Chown, 1998; Tickner et al., 2000). Despite their importance, little is known of habitat preferences of chi- ronomids, especially in the southern Mediterranean, including Algeria (Lounaci et al., 2000a; Lounaci et al., 2000b; Arab et al., 2004; Belaidi et al., 2004; Chaib et al., 2011a; Chaib et al., 2011b). Sampling in several wadis (water courses with very irregular hydro- Correspondence: Nadjla Chaib, Département de Génie des procédés, Faculté de Technologie, Université du 20 Août 1955, BP 26 Route El-Hadaëk, Skikda, Algeria. E-mail: nadjla21@yahoo.fr Key words: Algeria, Chironomidae, spatial distribution, substrate-type, Indval analysis, cluster analysis. Acknowledgements: the work was supported by the Algerian Ministère de l’Enseignement Supérieur et de la Recherche Scientifique (DGRSDT/M.E.S.R.S.) and the King Saud University Deanship of Scientific Research, Research Group Project No: RGP-VPP-135. DSFP, King Saud University, Saudi Arabia. Received for publication: 11 October 2012. Revision received: 12 November 2012. Accepted for publication: 21 December 2012. ©Copyright N. Chaib et al., 2013 Licensee PAGEPress, Italy Journal of Entomological and Acarological Research 2013; 45:e2 doi:10.4081/jear.2013.e2 This article is distributed under the terms of the Creative Commons Attribution Noncommercial License (by-nc 3.0) which permits any noncom- mercial use, distribution, and reproduction in any medium, provided the orig- inal author(s) and source are credited. Chironomid (Diptera, Chironomidae) species assemblages in northeastern Algerian hydrosystems N. Chaib,1,2 A. Fouzari,2 Z. Bouhala,2 B. Samraoui,2,3 B. Rossaro4 1Département de Génie des Procédés, Faculté de Technologie, Université du 20 Août 1955, Skikda, Algeria; 2Laboratoire de Recherche et de Conservation des Zones Humides, Université du 8 Mai 1945 Guelma, Algeria; 3Center of Excellence for Research in Biodiversity, King Saud University, Riyadh, Saudi Arabia; 4Department of Food, Environmental and Nutritional Sciences (DeFENS), Università degli Studi di Milano, Milano, Italy [page 4] [Journal of Entomological and Acarological Research 2013; 45:e2] Journal of Entomological and Acarological Research 2013; volume 45:e2 Jear_2013_1:Hrev_master 23/04/13 09.55 Pagina 4 No n c om me rci al us e o nly logic regime) in Kabily du Djurdjura, northern Algeria (Moubayed et al., 2007) generated a list of 87 chironomid species from this area: 8 belonged to Tanypodinae, 3 to Diamestinae, 57 to Orthocladinae and 19 to Chironomiae; 10 species were not described. A total of 53 species were new records for Algeria, 25 of which being also new records for North Africa. A survey of Chironomids from the Kebir-East wadi and its tributaries in northeastern Algeria (Chaib et al., 2011b) generated a list of 37 widespread chironomid species in the Palearctic. They include 5 Tanypodinae, 15 Orthocladiinae, 4 Tanytarsini and 13 Chironomini. A similar study was carried out in the Seybouse basin, where 45 chi- ronomid species were collected. This study aims to analyze the composition of Chironomidae assem- blages in the northeastern Algerian hydrosystems along the Kebir-East and the Seybouse wadis. The spatial distribution of the assemblages was examined and chironomids were correlated with substrate size in order to investigate substrate preferences. Materials and methods Study area Forty-nine sampling sites were chosen along the main course of the Kebir-East (23) and the Seybouse wadis (26) and their tributaries on the base of land-use and anthropogenic impacts (Chaib & Samraoui, 2011; Chaib et al., 2011a, 2011b; Khelifa et al., 2011) (Figure 1, Table 1). According to the subdivision of hydrographic nets in the eastern region of Algeria by the Agence des Bassins Hydrographiques (ABH- CSM), our two river systems, the subject of this paper, belong to two dif- ferent basins: i) the Kebir-East belongs to the watershed of the Côtiers Constantinois Est in the extreme north-east of Algeria, and covers a catchment area of 1600 km2; and ii) the Seybouse basin is the largest sub-basin in the northeastern region, covering an area of 6570 km2. These two fluvial systems are an important source of water in the northeastern Algeria, since they supply water for irrigation of large agricultural areas extending from the regions of Guelma to El Kala. Both the Seybouse and Kebir-East basins represent a mosaic of geo- morphodynamic natural conditions, as well as diverse levels of man- made disturbances of a variety of origins (physical: Bouhalloufa and Mexa dams for the Kebir-East and Bouhamdane dam for the Seybouse; chemical: presence of non-point pollutions, and municipal and indus- trial wastewater). The climate is typically Mediterranean with a hot and dry summer from June to September, and a cold and rainy winter from October to May. The substratum of the Kebir-East wadi is composed either of ancient sediments (marls and sandstone) of the Algerian local marine Miocene (equivalent to the continental Aquitanien), degraded slightly on the surface in the east, or more recent Plio-Quaternary sediments corre- sponding to alluviums of the high and middle terraces of the Kebir-East wadi valley. The recent Quaternary sediments in the valley of Kebir- East wadi comprise silt, sand and stones (Marre, 1987). The watershed of the Seybouse wadi drains water very slowly over a gentle relief from its source in the highlands of Sellawa and Heracta. In the uplands, it flows through a very fractured and complex structured topogra- phy, where the hydrographic net is rarely adapted to the structure (Ghachi, 1986). The effluents are torrential and the longitudinal contours are irreg- ular and stretched. The Seybouse River flows through some depressions containing an alluvial water table (C.G.G., 1971; Djabri et al., 2003). This allows regulation of winter precipitations received by the mountain range. When the river reaches the plain of Annaba, it loses its energy and leaves behind a great load of sediments. The geomorphological characteristics of the plain, gentle slope, sand dune barrier, and inundation-prone areas allow the river to flow easily into the Mediterranean Sea. All chironomid samples were collected with a Surber net (300 �m mesh size, 50 cm width). Sampling was carried out during spring (March-May) and summer (July-September) from 2008 to 2011. Ten hauls were made in the opposite sense of the current along the sam- [Journal of Entomological and Acarological Research 2013; 45:e2] [page 5] Article Figure 1. Location of the 49 sampling sites along the Kebir-East and the Seybouse wadis and their tributaries (northeastern Algeria). Jear_2013_1:Hrev_master 23/04/13 09.55 Pagina 5 No n c om me rci al us e o nly [page 6] [Journal of Entomological and Acarological Research 2013; 45:e2] Article Table 1. List of the sampled sites located along the Kebir-East and Seybouse wadis and their tributaries. No. Watercourse Names of the sampled sites Code Latitude Longitude Altitude Substrate size Substrate (N) (E) (m) size classes 1 O. Leben LEB 8°30’32’’ 36°46’56’’ 77 Very coarse gravel 5 2 O. Mellili MEL 8°30’28’’ 36°46’50’’ 80 Very fine gravel 4 3 O. Kebir at R’Mel Souk RSK 8°30’10’’ 36°46’55’’ 80 Very fine gravel 4 4 O. Louar Amont LAM 8°22’58’’ 36°36’52’’ 652 Stones 6 5 O. Louar Aval LAV 8°21’56’’ 36°39’01’’ 200 Silt 1 6 O. Bougous Amont BAM 8°21’53’’ 36°39’06’’ 203 Very fine gravel 4 7 O. Bougous Aval BAV 8°24’27’’ 36°42’36’’ 69 Very coarse gravel 5 8 O. Kebir at Ain Assel KAS 8°21’57’’ 36°45’59’’ 30 Very fine gravel 4 9 Oubéïra 3 OB3 8°23’10’’ 36°51’47’’ 24 Silt 1 10 Oubéïra 2 OB2 8°25’15’’ 36°51’29’’ 24 Silt 1 11 Oubéïra 1 OB1 8°24’12’’ 36°49’29’’ 22 Silt 1 12 O. Messida Aval MAM 8°24’09’’ 36°49’23’’ 22 Very fine sand 2 13 O. Messida Amont MAV 8°22’30’’ 36°47’37’’ 25 Very fine sand 2 Kebir-east wadi 14 O. Kebir Ain Khiar KAK 8°18’51’’ 36°46’49’’ 23 Very coarse sand 3 15 O. Guergour GRG 8°16’52’’ 36°46’32’’ 25 Very coarse sand 3 16 O. Kebir Guergour KGR 8°16’43’’ 36°46’36’’ 25 Silt 1 17 O. Bourdim BRD 8°14’50’’ 36°47’22’’ 20 Very fine gravel 4 18 O. Zitoun ZIT 8°13’02’’ 36°39’06’’ 193 Stones 6 19 O. Dardan DRD 8°13’16’’ 36°46’39’’ 15 Silt 1 20 O. Kebir at Anenes KAN 8°12’48’’ 36°47’48’’ 14 Very fine sand 2 21 O. Kebir at Righia KRG 8°09’35’’ 36°48’51’’ 11 Silt 1 22 O. Boulathan BLT 8°06’06’’ 36°49’42’’ 8 Very fine sand 2 23 O. Kebir at Sebaa KSB 8°09’07’’ 36°48’59’’ 10 Silt 1 24 Barrage Sedrata BSD 36°03.516’ 7°27.209’ 744 Silt 1 25 Cherf à Sedrata CPS 36°04.479’ 7°29.640’ 747 Silt 1 26 Oued Krab OKR 36°07.210’ 7°32.780’ 778 Silt 1 27 Cherf à Ksar Sbahi CKS 36°03.207’ 7°19.557’ 751 Silt 1 Seybouse wadi 28 Oued El Nil ONL 36°08.380’ 7°26.731’ 775 Very coarse gravel 5 29 Oued Dbabcha ODB 36°12.945’ 7°19.047’ 609 Very coarse gravel 5 30 Oued el Maleh OML 36°08.893’ 7°8.642’ 742 Very fine sand 2 31 Oued Beni Mheni OBM 36°09.207’ 7°19.557’ 668 Very fine sand 2 32 Barrage Ain Makhlouf BMK 36°13.528’ 7°17.783 643 Stones 6 33 Oued El Aare OAR 36°13.572’ 7°19.186’ 609 Stones 6 34 Cherf à Ain Makhlouf CMK 36°14.462’ 7°18.626’ 600 Stones 6 35 Oued Cheniour- Affluent OCH 36°14.877’ 7°20.610’ 742 Stones 6 36 Cherf à Ain Hsainia CHS 36°25.415’ 7°18.788’ 270 Very fine gravel 4 37 Cherf à Medjez Amar CMA 36°26.526’ 7°18.677’ 273 Very fine gravel 4 38 Bouhamdane à Hammam Debagh BHD 36°28.012’ 7°15.673’ 305 Very fine gravel 4 39 Bouhamdane à Mermoura BMR 36°26.522’ 7°16.292’ 480 Stones 6 40 Bouhamdane à Medjez Amar BMA 36°36.592’ 7°18.615’ 274 Very fine gravel 4 41 Seybouse à Salah SalahSalah SSS 36°27.697’ 7°20.382’ 251 Stones 6 42 Seybouse à El –Fedjouj SFJ 36°28.893’ 7°24.926’ 222 Stones 6 43 Oued Zimba – effluent OZM 36°26.020’ 7°18.452’ 291 Very fine sand 2 44 Oued Bradâa OBR 36°30.803’ 7°27.037’ 285 Very coarse sand 3 45 Oued Helia – effluent OHL 36°25.415’ 7°18.788’ 144 Stones 6 46 Seybouse à Zemzouma SZM 36°24.795’ 7°36.676’ 143 Very fine sand 2 47 Seybouse à Boudaroua SBD 36°31.667’ 7°42.307’ 100 Very fine gravel 4 48 Seybouse à Chihani SCH 36°41.002’ 7°45.527’ 12 Very coarse sand 3 49 Seybouse à Dreân SDR 36°39.216’ 7°46.968’ 18 Very fine gravel 4 Jear_2013_1:Hrev_master 23/04/13 09.55 Pagina 6 No n c om me rci al us e o nly [Journal of Entomological and Acarological Research 2013; 45:e2] [page 7] Article Table 2. List of species recorded in 49 sites from two northeastern Algerian watercourses (Kebir-East and Seybouse wadis) between 2007 and 2011. Subfamilies are presented in phylogenetic order and genera in alphabetic order. Taxa Frequency of occurrence (%) Total abundance of species Tanypodinae Conchapelopia pallidula (Meigen, 1818)* 1.17 103 Procladius choreus (Meigen, 1804)° 0.75 66 Rheopelopia ornata (Meigen, 1838)# 1.12 99 Tanypus punctipennis Meigen, 1818° 1.36 120 Zavrelimyia punctatissima (Goetghebuer, 1934)* 0.19 17 Diamesinae Sympotthastia spinifera (Serra-Tosio, 1968)# 0.01 1 Prodiamesinae Prodiamesa olivacea (Meigen, 1818)° 0.05 4 Orthocladiinae Cardiocladius fuscus Kieffer, 1924# 0.82 72 Corynoneura scutellata Winnertz, 1846° 0.14 12 Cricotopus (Cricotopus) bicinctus (Meigen, 1818)° 29.52 2606 Cricotopus (Isocladius) sylvestris (Fabricius, 1974)° 9.39 829 Eukiefferiella bedmari Vilchez-Quero & Laville, 1987* 0.25 22 Eukiefferiella claripennis (Lundbeck, 1890)° 0.8 71 Eukiefferiella gracei (Edwards, 1929)* 0.01 1 Eukiefferiella ilkleyensis (Edwards, 1929)* 0.09 8 Eukiefferiella sp.1 (Thienemann A., 1926)* 0.02 2 Hydrobaenus distylus (Potthast, 1914)# 0.93 82 Hydrobaenus sp.1 Fries, 1830* 0.02 2 Limnophyes minimus (Meigen, 1818)* 0.01 1 Metriocnemus sp.1 Van Der Wulp, 1874* 0.03 3 Orthocladius (Euorthocladius) ashei Soponis, A., 1990* 0.25 22 Orthocladius (Euorthocladius) rivicola Kieffer, 1911# 3.15 278 Orthocladius (Orthocladius) excavatus Brundin L., 1947* 1.36 120 Orthocladius (Orthocladius) rubicundus (Meigen, 1818)* 0.61 54 Orthocladius pedestris Kieffer, 1909# 3.18 281 Paracladius conversus (Walker, 1856)# 0.01 1 Parakiefferiella gracillima (Kieffer, 1924)# 0.05 4 Parametriocnemus stylatus (Kieffer, 1924)° 0.27 24 Paraphaenocladius sp.1 Thienemann, 1924* 0.01 1 Paratrichocladius rufiventris (Meigen, 1830)* 2.38 210 Paratrissocladius excerptus Walker, 1846# 0.12 11 Psectrocladius (Psectrocladius) psilopterus (Kieffer, 1906)* 0.11 10 Psectrocladius sordidellus (Zetterstedt, 1838)# 0.02 2 Rheocricotopus chalybeatus (Edwards, 1929)# 3.32 293 Rheocricotopus fuscipes (Kieffer, 1909)* 1.6 141 Thienemanniella vittata (Edwards, 1924)° 0.33 29 Tanytarsini Cladotanytarsus mancus (Walker, 1856)# 1.08 95 Cladotanytarsus sp.1 Kieffer, 1921* 0.35 31 Micropsectra atrofasciata (Kieffer, 1911)# 0.06 5 Paratanytarsus sp.1 (Thienemann A. & Bause, 1913)* 1.22 108 Rheotanytarsus photophilus (Goetghebuer, 1921)# 0.71 63 Rheotanytarsus sp.1 Thienemann A. & Bause, 1913* 0.51 45 Tanytarsus sp.1 Van der Wulp, 1874° 1.11 98 Chironominae Chironomus plumosus (Linnæus, 1758)° 2.41 213 Chironomus riparius Meigen, 1804# 7.15 631 Chironomus sp.1 Meigen, 1803* 2.7 238 Cryptochironomus defectus (Kieffer, 1913)* 0.32 28 Cryptochironomus rostratus Kieffer, 1921# 0.11 10 Cryptotendipes sp.1 Beck & Beck, 1969* 0.01 1 Dicrotendipes nervosus (Stäger, 1839)° 0.82 72 Einfeldia sp.1 Kieffer, 1924* 0.01 1 Genus near Tribelos* 0.23 20 Glyptotendipes pallens (Meigen, 1804)# 0.08 7 Harnischia fuscimana (Kieffer, 1921)° 0.1 9 Microchironomus tener (Kieffer, 1818)# 0.01 1 Microtendipes pedellus (De Geer, 1776)° 0.74 65 Paracladopelma camptolabis (Kieffer, 1913)# 0.01 1 Phaenopsectra flavipes (Meigen, 1818)* 0.02 2 Polypedilum (Tripodura) scalaenum (Schrank, 1803)° 3.09 273 Polypedilum cultellatum (Goetghebuer, 1931)° 8.7 768 Polypedilum laetum (Meigen, 1818)* 0.03 3 Polypedilum nubifer (Skuse, 1889)* 4.73 418 Robackia sp.1 Sæther O.A., 1977* 0.02 2 Synendotendipes dispar (Meigen, 1830)# 0.19 17 Synendotendipes impar (Walker, 1856)* 0.01 1 *Species recorded in the Seybouse wadi. °Species recorded in both the Kebir-East and the Seybouse wadis. #Species recorded in the Kebir-East. Total abundance was calculated as the abundance from all samples (n=49) pooled together. Jear_2013_1:Hrev_master 23/04/13 09.55 Pagina 7 No n c om me rci al us e o nly [page 8] [Journal of Entomological and Acarological Research 2013; 45:e2] pling station, in the middle of the current and near the banks. Samples were preserved in 5% formaldehyde (larvae, pupae), and then exam- ined under a dissecting microscope. The specimens were grouped by morphotypes according to external characteristics visible through the stereomicroscope in the laboratory. Subsequently permanent mounts were prepared in Faure or in Balsam mounting medium, to enable the taxonomic determination of the different morphotypes. Dataset A list of species derived from different studies carried out in north- eastern Algeria between 2007 and 2011 (Chaib et al., 2011b) were col- lected in a database. The list was based on larval collections, with species identification aided by collection of prepupae and of mature pupae. Italian Keys for larvae determination were used (Ferrarese, 1983; Ferrarese & Rossaro, 1981; Nocentini, 1985; Rossaro, 1982) along with keys for Palaearctic pupae (Langton & Visser, 2003). Substrate size was ranged into six classes (ISO 14688-1) according to the particle size: i) class 1: silt, <0.063 mm; ii) class 2: fine sand, 0.063-0.200 mm; iii) class 3: medium-coarse sand, 0.200-2 mm; iv) class 4: fine-medium gravel, 2-20 mm; v) class 5: coarse gravel, 20-63 mm; vi) class 6: cobble, 63-200 mm. Data analysis Quantitative samples collected in the 49 sampling sites were consid- ered in the statistical analyses; the mean abundance of each taxon per site was considered. Rare species were included in the analysis (Smith et al., 2001) resulting in a total of 65 taxa. Relative abundances of species were transformed by log (10) to nor- malize counts. To avoid a problem of logarithm zeroes, the value 1 was added to each abundance. Groups of samples sharing the same type of community composition were defined using a hierarchical cluster analysis (Goodall, 1973) with Ward’s linkage method and Euclidian dis- tance measure. Multi-response permutation procedures (MRPP) (Biondini et al., 1985) were used to test the reliability of the groups obtained. The species characterizing each cluster were identified with indica- tor species analysis (IndVal; Dufrêne & Legendre, 1997). A second Indval analysis was carried out considering the sampling sites grouped based on substrate size. This method combines information on the con- centration of species abundances in a particular group and the faithful- ness of occurrence of a species in a particular group. Indicator values were tested for statistical significance using a randomization (Monte Carlo) technique (McCune & Grace, 2002). The significance was test- ed by carrying out 10,000 Indval analyses. Agglomerative cluster analysis, MRPP and Indval analysis were per- formed with the R environment 2.15.1 (R Development Core Team, 2009). Species richness, diversity and evenness indices were also calculat- ed (Shannon & Weaver, 1949). Results Sixty-five Chironomidae taxa belonging to four subfamilies were identified (Table 2). Orthocladiinae showed the highest generic rich- ness (29 taxa). This subfamily showed a proportional abundance of 59%, Chironominae 31%. Tanytarsini and Tanypodinae were the less frequent and abundant with approximately 6% and 5%, respectively. C. bicinctus showed the highest abundance (2606 ind*m-2) and fre- quency of occurrence (29.52%) and was widespread in almost all the sampling sites (Table 2), followed by C. sylvestris and Polypedilum cul- tellatum with total abundance of 829 and 768, and a frequency of occur- rence of 9.39% and 8.7%, respectively. Total abundance and the fre- Article Figure 2. Agglomerative cluster dendrogram based on chironomid communities sampled in the Kebir-East and the Seybouse wadis (2008-2011) (see Table 1 for site codes and names of sampling sites for each group). Jear_2013_1:Hrev_master 23/04/13 09.55 Pagina 8 No n c om me rci al us e o nly [Journal of Entomological and Acarological Research 2013; 45:e2] [page 9] Article Table 3. Chironomids diversity, richness and evenness for the each sampling sites (see Table 1 for site codes; see Figure 2 for clusters). No. Sampled sites Cluster Diversity Species Evenness richness 1 LEB 1 0.75 14 0.66 2 MEL 2 0.64 14 0.58 3 RSK 1 0.81 11 0.75 4 LAM 1 0.75 15 0.66 5 LAV 3 0.81 12 0.76 6 BAM 3 0.63 11 0.57 7 BAV 4 0.80 14 0.73 8 KAS 4 0.79 22 0.72 9 OB3 3 0.75 8 0.76 10 OB2 4 0.64 9 0.64 11 OB1 4 0.72 9 0.71 12 MAM 4 0.84 16 0.76 13 MAV 3 0.74 15 0.64 14 KAK 1 0.64 11 0.54 15 GRG 1 0.62 11 0.59 16 KGR 2 0.62 12 0.54 17 BRD 2 0.80 14 0.72 18 ZIT 4 0.15 5 0.23 19 DRD 4 0.82 13 0.76 20 KAN 1 0.75 9 0.73 21 KRG 4 0.71 12 0.59 22 BLT 4 0.73 11 0.66 23 KSB 4 0.76 12 0.70 24 BSD 4 0.25 9 0.28 25 CPS 4 0.83 19 0.72 26 OKR 4 0.77 9 0.77 27 CKS 3 0.90 18 0.86 28 ONL 4 0.78 8 0.85 29 ODB 4 0.89 15 0.87 30 OML 4 0.83 9 0.89 31 OBM 4 0.63 9 0.61 32 BMK 4 0.72 7 0.77 33 OAR 4 0.75 4 1.00 34 CMK 4 0.89 20 0.83 35 OCH 4 0.77 23 0.68 36 CHS 1 0.81 17 0.74 37 CMA 4 0.89 20 0.85 38 BHD 4 0.73 10 0.75 39 BMR 4 0.80 11 0.81 40 BMA 4 0.70 17 0.64 41 SSS 4 0.85 17 0.78 42 SFJ 4 0.89 17 0.86 43 OZM 4 0.84 23 0.72 44 OBR 4 0.77 12 0.76 45 OHL 4 0.78 19 0,74 46 SZM 1 0.85 17 0.78 47 SBD 4 0.76 15 0.74 48 SCH 4 0.81 16 0.78 49 SDR 1 0.81 15 0.73 Table 4. Chironomid indicator species by group of sites and sub- strate size (Indval analysis). Taxa Substrate assemblages size Taxa Max P Max P class class Tanypodinae Conchapelopia pallidula 4 0.378 6 0.324 Procladius choreus 3 0.102 1 0.235 Rheopelopia ornata 3 0.144 5 0.575 Tanypus punctipennis 1 0.749 4 0.519 Zavrelimyia punctatissima 4 0.292 3 0.581 Diamesinae Sympotthastia spinifera 2 0.057 4 0.746 Prodiamesinae Prodiamesa olivacea 4 0.719 4 0.356 Orthocladiinae Cardiocladius fuscus 2 0.042 3 0.417 Corynoneura scutellata 2 0.643 4 0.032 Cricotopus (Cricotopus) bicinctus 2 0.011 4 0.510 Cricotopus (Isocladius) sylvestris 1 0.029 5 0.809 Eukiefferiella bedmari 4 0.691 6 0.571 Eukiefferiella claripennis 2 0.112 6 0.923 Eukiefferiella gracei 4 1.000 4 0.776 Eukiefferiella ilkleyensis 4 1.000 6 0.270 Eukiefferiella sp.1 4 1.000 6 0.898 Hydrobaenus distylus 2 0.116 4 0.807 Hydrobaenus sp.1 4 1.000 3 0.455 Limnophyes minimus 3 0.164 1 1.000 Metriocnemus sp.1 3 0.390 1 0.757 Orthocladius (Euorthocladius) ashei 3 0.537 6 0.745 Orthocladius (Euorthocladius) rivicola 3 0.934 6 0.796 Orthocladius (Orthocladius) excavatus 4 0.609 2 0.342 Orthocladius (Orthocladius) rubicundus 3 0.750 6 0.502 Orthocladius pedestris 2 0.007 4 0.129 Paracladius conversus 4 1.000 2 0.314 Parakiefferiella gracillima 2 0.114 4 0.271 Parametriocnemus stylatus 2 0.572 4 0.297 Paraphaenocladius sp.1* 4 1.000 6 0.538 Paratrichocladius rufiventris 4 0.265 3 0.542 Paratrissocladius excerptus 3 0.941 6 0.057 Psectrocladius (Psectrocladius) psilopterus 4 0.724 2 0.497 Psectrocladius sordidellus 1 0.569 2 0.725 Rheocricotopus chalybeatus 2 0.009 3 0.971 Rheocricotopus fuscipes 4 0.387 6 0.118 Thienemanniella vittata 2 0.533 1 0.139 Tanytarsini Cladotanytarsus mancus 1 0.586 4 0.466 Cladotanytarsus sp.1 4 0.609 3 0.732 Micropsectra atrofasciata 4 1.000 4 0.754 Paratanytarsus sp.1 1 0.945 4 0.684 Rheotanytarsus photophilus 2 0.319 5 0.539 Rheotanytarsus sp.1 4 0.189 6 0.248 Tanytarsus sp.1 4 0.811 3 0.764 Chironominae Chironomus plumosus 2 0.276 1 0.536 Chironomus riparius 4 0.744 2 0.156 Chironomus sp.1 4 0.661 6 0.534 Cryptochironomus defectus 1 0.805 6 0.428 Cryptochironomus rostratus 3 0.065 4 0.632 Cryptotendipes sp.1 1 0.335 2 0.309 Dicrotendipes nervosus 2 0.761 4 0.033 Einfeldia sp.1 1 0.349 5 0.150 Genus near Tribelos 4 1.000 1 1.000 Glyptotendipes pallens 3 0.379 2 0.036 Harnischia fuscimana 2 0.638 6 0.276 Microchironomus tener 3 0.140 4 0.756 Microtendipes pedellus 3 0.655 5 0.441 Paracladopelma camptolabis 1 0.357 6 0.530 Phaenopsectra flavipes 3 0.306 4 1.000 Polypedilum (Tripodura) scalaenum 3 0.091 1 0.774 Polypedilum cultellatum 3 0.038 1 0.616 Polypedilum laetum 1 0.776 4 0.500 Polypedilum nubifer 4 1.000 6 0.211 Robackia sp.1 4 0.155 1 0.937 Synendotendipes dispar 2 0.052 5 0.124 Synendotendipes impar 4 1 4 0.747 Significant values (P<0.05) are in italics (see Figure 2 for groups of sites: cluster analysis). *Species recorded in the Seybouse wadi. Jear_2013_1:Hrev_master 23/04/13 09.55 Pagina 9 No n c om me rci al us e o nly [page 10] [Journal of Entomological and Acarological Research 2013; 45:e2] quency of occurrence were calculated from all samples (n=49) pooled together. Species Richness ranged from 4 (site 33) to 23 (sites 35 and 43), diversity between 0.15 (site 18) and 0.90 (site 27). Evenness values ranged from 0.23 (site 18) to 1 (site 33) (Table 3). Indicator species were determined for each group of sites and then according to substrate-type. Indicator values are in Table 4, along with statistical significance values calculated by randomization (Monte Carlo) (McCune & Grace, 2002). The agglomerative cluster analysis (Figure 2) grouped the sampling sites into clusters according to the chironomid species. A 4-group level of the dendrogram was chosen, the MRPP results showing that the groups obtained were statistically different (A=0.302, P<0.005). Corynoneura scutellata and Dicrotendipes nervosus showed the low- est P values (0.032 and 0.033, respectively) and seemed to have a pref- erence to very fine gravel, Glyptotendipes pallens presented a P value of 0.036 suggesting a preference for very fine sand substrate (Table 1). It should be emphasized that the number of larvae recorded of C. scutellata and G. pallens was very low; only a few larvae were captured in some stations. D. nervosus was more abundant in stations KAS (20 larvae) and SDR (12 larvae). Discussion and conclusions The percentage distribution of taxa within chironomid subfamilies was in accordance with previous studies (Moubayed et al., 2007; Chaib et al., 2011b), with Orthocladiinae as the most frequent, taxon-richest and abundant subfamily. C. bicinctus was the most abundant and widely distributed taxon, confirming that the species can tolerate a wide range of substrate size (with a preference for the sandy substrate). In contrast C. scutellata was the least abundant, present only in very fine gravel substrates. The cobble and gravel substrates held the highest number of chirono- mids among all substrates (Table 1). It was similarly observed (Campbell & Meadows, 1972) that cobble substrates offer the most suitable microenvironments because they supply materials used by the larvae to construct runways and to build cases about their bodies, crevices for pro- tection, sources of attachment, they are also a source of food since rock surfaces are covered with periphyton (mosses and algae). In contrast, silty stations housed the least number of chironomids (Table 1) due to the fact that they had the least favorable physical con- ditions, such as high current and low values of organic matter and transparency. However, P. cultellatum was found to be dominant there. 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