% 8S UULT ETINJL-1 4 y M of the FLORIDA STATE MUSEUM Biological Sciences Volume 31 1987 Number 4 FRESHWATER FISHES OF SOUTHERN FLORIDA William F. Loftus and James A. Kushlan . 9 3 / , p 9 4~ ~ S i S., . 98* 5 / , 5 r 1, E% =1 ' Sts 0' UNIVERSITY OF FLORIDA GAINESVILLE - Numbers of the BULLETIN OF THE FLORIDA STATE MUSEUM, BIOLOGICAL SCIENCES, are published at irregular intervals. Volumes contain about 300 pages and are not necessarily completed in any one calendar year. OLIVER L. AUSTIN, JR., Editor S. DAVID WEBB, Associate Editor ]RHODA J. BRYANT, Managing Editor Consultants for this issue: GEORGE H. BURGESS WALTER R. COURTENAY, JR. FRANKLIN F. SNELSON, JR. Communications concerning purchase or exchange of the publications and all manuscripts should be addressed to: Managing Editor, Bulletin; Florida State Museum; University of Florida; Gainesville FL 32611; U.S.A. This public document was promulgated at an annual cost of $6912.00 or $6.912 per copy. It makes available to libraries, scholars, and all interested persons the results of researches in the natural sciences, emphasizing the circum-Caribbean region. ISSN: 0071-6154 CODEN: BF 5BAS Publication date: 27 November 1987 Price: $7.20 FRESHWATER FISHES OF SOUTHERN FLORIDA William F. Loftus and James A. Kushlan* ABSTRACT This paper presents the results of the first systematic study of the distribution of fishes in southern Florida's fresh waters. Prior to this study, the known ranges of many fishes at the southern tip of Florida were either poorly understood or in error. The presence of 92 species of fishes in fresh water is documented for extreme southern Florida. The status and distribution of the fishes and the ecological factors that affect them are discusded. Individual species accounts describe each fish's range in southern Florida and provide life history and ecological data. Locations and descriptions of collection sites, an artificial key to juvenile Lepomis species, and a bibliography of southern Florida freshwater fishes are included. This study produced records for several species, such as Carcharhinus leucas, Floridichthys carpio, Fundulus similis, and Agonostomus monticola, that were not well known from southern Florida fresh waters. It also documents freshwater penetration by nine euryhaline species that were not listed from fresh water by Robins et aI. (1980): Adinia xenica, Floridichthys carpio, Fundulus similis, Epinephelus itaiara, Caranx hipoos, Olizoplites saurus, Sphwaena barracuda, Gobionellus smaragdus, and I«ophogobius cyprinoides. The centrarchids Lepomis Rulosus and Lepomis punctatus were collected at their highest recorded salinity, 12.5 0/00. New distributional data have extended the known freshwater ranges of 15 species into extreme southern Florida. Records for freshwater occurrence or persistence by 11 species in southern Florida are regarded as erroneous or dubious. The presence of 12 non-native species is documented, one of which, Cichlasoma citrinellum, is a recent introduction. Distinct distributional patterns exist for several groups of species: Iarge tentrarchids occur primarily in canals, cypress sloughs, and headwater rivers; most euryhaline species do not * William F. Loftus is a fishery biologist with the U.S National Park Service at the 5outh Florida Research Center, Everglades National Park, P.O. Box 279, Homestead FL 33030. James A. Kushlan, formerly a research biologist at the South Florida Research Center, is an associate professor in the Department of Biology, East Texas State University, Commerce TX 75428. LOFIUS, W.F., AND J.A. KUSHLAN. 1987. Freshwater fishes of southern Florida. Bull. Florida State Mus., Biol. Sci. 31(4):147-344. 148 BULLETIN FLORIDA SrATE MUSEUM VOL. 31(4) penetrate far inland; the majority of exotic species are most numerous in the canal system; and many small cyprinodontoids are widely distributed in all habitats. The relative abundance of fish species usually varies among habitats. All native primary and secondary freshwater fish species in southern Florida are derived from temperate North American waters. Most are widespread in the southeastern United States. All established non-native species originated in tropical or subtropical regions. RESUMEN Este articulo presenta los resultados del primer estudio sistematico de peces de aguas continentales ("agua dulce") en el sur de la Florida. Antes de este estudio, los rangos de distribuci6n de muchas especies en el extremo sur de Florida eran poco conocidos o err6neos. Se documenta la existencia de 92 especies de peces continentales y se discuten los factores ecologicos que afectan su status y distribuci6n. Se hace tambi6n una descripci6n del rango de distribuci6n por especie y se da informaci6n pertinente acerca de su historia natural y ecologia. Se incluye la localizaci6n y descripci6n de Areas de recolecci6n, una clave artificial para los juveniles de Lepomis sp., asi como una bibliografia sobre peces continentales deI sur de Florida. La recolecci6n de especimenes y la revisi6n de literatura permitieron hacer registros de especies no bien conocidas de aguas continentales del sur de Florida. Entre ellas: Carcharhinus leucas, Floridichthys carr)io, Fundulus similis, Epinephelus itaiara, Caranx hippos, Oligoplites saurus, Sphwaena barracuda, Gobionellus smarazdus, y Lophozobius cvprinoides. Dos centrarquidos, Lepomis gulosus y Lepomis punctatus, fueron recolectados en aguas cuya salinidad es la maxima registrada para estas especies, 12.5 0/00. Nueva evidencia permite extender el rango distribucional de 15 especies en el extremo sur de Florida. Previos registros acerca de la existencia de 11 especies en aguas continentales del sur de Florida, son considerados err6neos o dudosos. Se documenta la presencia de 12 especies no nativas, una de Ias cuales, Cichlasoma citrinellum, fue recientemente introducida. Existen patrones distribucionales distintos para varios grupos de especies. Los centrarquidos grandes habitan principalmente en canales, pantanos de cipreses y cabeceras de rios; la mayoria de las especies eurihalinas no penetran en el interior; la mayoria de las especies ex6ticas son mas numerosas en los sistemas de canales; mientras que muchos ciprinodontoides estdn ampliamente representados en la mayoria de los hdbitats. La abundancia relativa de estas especies generalmente varia de acuerdo al hbbitat. Todas las especies primarias y secundarias de aguas continentales, provienen de zonas templadas de America del Norte. La mayoria de ellas estdn ampliamente distribuidas en el sudeste de los Estados Unidos. Todas las especies no nativas estableci{las en el brea provienen de regiones tropicales y subtropicales. LOFIUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 149 TABLE OF CONTENTS Introduction.................................................................................................................................................. 149 Acknowledgements 1S1 Description of the Study A rp 9 1 S1 177Species Accounts................................................................................................................................. Species of Doubtful Occurrence or Persistence Hybri,ls ...274 Discussion Range Revisions and New Records.................................................................................................276 Faunal Derivation and Salinity Relations 778 Habitat Occurrence and Distribution Patterns ........................................................................ 282 Everglades Marsh Prairies.........................................................................................................282 Everglades Sawgrass Marshes....................................................................................................283 Everglades Alligator Ponds 7*3 Big Cypress Swamp 284 Canal System...............................................„„-. -..,................„-...„....284 Coastal habitats..............................„,.„-..„,......-„„„- -............„................„„..................,.„.,....290 Introduced Fishes 900 Factors Affecting the Fkheq 7Q5 Summary ?Q9 Literature Citpri lAn Appendix I. Collection Site Descriptions Appendix II. A Listing of the Voucher Samples and Museum Catalogue Numbers...................336 Appendix III. An Artificial Key to Juvenile Sunfishes of the Genus Lepomis ............................... from Southern Florida..........................„„„„~~~- -.........,.„ „....343 INTRODUCTION The Everglades, Big Cypress Swamp, and contiguous freshwaters in southern Florida offer one of the most extensive wetland environments in the United States. It is, therefore, surprising that study of freshwater fishes in southern Florida has beeR neglected in comparison with that of freshwater areas farther north or with that of marine fishes in southern Florida. Although the component species of the ichthyofauna had been described and listed in works by Evermann and Kendall (1900), Fowler (1945), Carr and Goin (1955), and Briggs (1958), just one distributional study had been conducted in this region, based upon limited collections in and near Everglades National Park (Kilby and Caldwell 1955). Available distributional data for freshwater fishes in southern Florida were summarized by Kushlan and Lodge (1974). This 150 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) situation is reflected in the incomplete distribution maps in the work by Lee et al. (1980) on North American fishes. Life history and ecological studies of fishes are somewhat more substantial. They include work on food habits (Hunt 1953; Odum 1971) and seasonal ecology in the Big Cypress Swamp (Kushlan 1974a, 1976a), in the Everglades marshes (Tabb 1963; Kolipinski and Higer 1969; Kushlan 1976b, 1980a), and in the mangrove zone (Tabb and Manning 1961; Tabb et al. 1974). Several studies document changing distribution of introduced fishes in southern Florida (Courtenay and Robins 1973; Courtenay et al. 1974; Hogg 1976a). Ichthyological studies in areas adjoining ours include those from the northern Everglades Water Conservation Areas (Clugston 1966; Crowder 1974; Dineen 1974), the Fakahatchee Strand (Carter et al. 1973), northern Big Cypress Swamp (Carlson and Duever 1977), Lake Okeechobee (Ager 1971), the St. Lucie River (Gunter and Hall 1963a), and the Caloosahatchee River (Gunter and Hall 1965). The paucity of information on southern Florida freshwater fishes is critical in view of their central ecological role in freshwater marshes and swamps (Kushlan et al. 1975; Ogden et al. 1976; Kushlan 1979a, 198Ob). The study of freshwater fishes in southern Florida has been limited by the inaccessibility of much of the region and by technical sampling problems. Roadways are few through the Everglades and Big Cypress Swamp, and most travel must be by airboat, swamp buggy, or helicopter--all relatively expensive modes of transport. Secondly, it is difficult to obtain adequate and representative samples in habitats that do not lend themselves to the use of ordinary fish-sampling gear and techniques. These difficulties have resulted in the development of new techniques for quantitative sampling in marsh habitats in southern Florida (Higer and Kolipinski 1967; Kushlan 1974b, 1981). This survey of the freshwater fish fauna of extreme southern Florida was the first step of a larger study of fish ecology in the Everglades. Our sampling program extended from December 1976 through April 1983. The purposes of the study were to document the distribution and composition of the ichthyofauna, to search for geographical differences in the ichthyofauna within the study area, to obtain qualitative data on habitat occurrence, and to determine the present extent of invasions by exotic fishes. In reviewing the literature from our study area, we found records for a number of species that we did not collect in our sampling. We include these in this paper. These baseline data on native and exotic fish species and their present ranges will allow future changes in their distribution to be measured. LOFI'US & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 151 ACKNOWLEDGEMENTS We wish to thank Scott Andree, David Tomey, Carol Hewes, Nancy Deschu, Karen Kronner, and especially Scott A. Voorhees for help in the fieId and in sorting and curating the samples. Paula C. Frohring, Joanna Booser, Ronald Wideman, Lori Lagna, and Dorothy Peck supplied important information from coastal areas. We also'appreciate the help of the following persons in the field: Jeffrey Aresty, Robert Austin, Oron L. Bass, Jr., M. Christine Baumann, Joanna Booser, David Buker, James Chapman, Richard Coleman, James Craig, Douglas Cuillard, William Debusk, Paula Frohring, Steven Jansen, Terry Kranzer, Bland Lawson, William Magnusson, Linda McEwan, Gary Novotny, Dennis Ojima, Gary Patterson, Dorothy Peck, Raoul Rehrer, Peter Rosendahl, Edward Rutherford, Mark Salzburg, Todd Steiner, George Tamm, and Ronald Wideman. We thank Mark Hudy and Richard Gregory for sharing distribution data on fishes from Dade County rockpits. Discussions with Luis R. Rivas and Carter R. Gilbert on the fish fauna were very valuable, as were comments on centrarchid hybrids by Reeve M. Bailey, and on killifishes by Kenneth Relyea. We especially thank George H. Burgess, Walter R Courtenay, Jr., J. Walter Dineen, R. Grant Gilmore, Thomas E. Lodge, William B. Robertson, Jr., C. Richard Robins, Martin A. Roessier, Paul L Shaf[and, and Durbin C. Tabb who read and commented on the manuscript; each provided many helpful suggestions. We are indebted to J.B. Miller and G.H. Burgess of the Florida State Museum for cataloguing our specimens and proofing our collection data. Tony Caprio photographed the habitat figures. We especially thank Dottie Anderson, Betty CurI, Fay Schattner, Dee Childs, and Jessie Brundige for typing the manuscript in its several forms. DESCRIPTION OF THE STUDY AREA The study area included all freshwater habitats on the mainland of southern Florida (Fig. 1) south of the Tamiami Trail (U.S. Hwy. 41), from Miami west to Everglades City, including Cape Sable (Fig. 2). Except for the canalized, developed zone along the eastern and western coasts, most of southern Florida is covered with seasonally flooded marshes and swamps. The two major natural drainages in this area are the Everglades marsh system called Shark River Slough (south of Tamiami Trail) and the Big Cypress Swamp (Fig. 3). The third drainage system is the artificial network of canals that dissect the southern Everglades and the eastern coastal ridge. These generally follow the course of pre-existing transverse glades that drained the coastal pinelands to Biscayne Bay (Fig. 3). The hydrology of the area has been described by Parker et al. (1955) and Klein et al. (1970). Although some pools of fresh water occur on the Florida Keys, we did not include the keys within our study area. Most of these pools occur on the 152 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) 1 ST. LUCIE 1 COUNTY HIGHLANDS DE SOTO COUNTY COUNTY _1 MARTIN COUNTY . STUART CHARLOTTE GLADES COUNTY LAKE ST tle,E G COUNT¥ OKEECHOBEE PALM BEACH tE RIVER COUNTY WEST PALM 6 BEACH CAL(O HENDRY COUNTY FORT MYERS/4 I,MOKILIE\\1 85 "r 1 i BOCA RATON \CORNES~ 1 ~ No. 2 1 COLLIER , CONSERVATION 1 NAPLES COUNTY |AREA NO, 3 D", 3 BIG FORT N ¥ 3 1 0 3 11 N V U v W ~ BROWARD LAUDERDALE N CYPRESS -1--' IM )--- HOLLYWOOD COUNTY 4 SWAMP , 3 US.HWY.41 THOUSAN.I.. MIAMI ISLANDS .3 - -- £- --, MIAMI TAMIAMI TRAll BEACH LZMONROE GULF OF MEXICO . COUNTY 1 +7 DADE / 6 BISCAYNE COUNTY Q Z HOMESTEAD EVERGLADES NAlloNAL ./ 3. PARK BOUNDARY BEACH *** Ip-3 .. CONSERVATION AREA f BOUNDARY WHIEW.,ER \ 1 ~.1 LIlli IAY COUNTY LINES KEN V e '*0 1 , CAPE SABLE . FLAMINGO , /,g~ /2.o 0 25 50 FLORIDA BAY * 4 KILOMETERS <* Figure 1.- Map of Florida, south of Lake Okeechobee, showing geographical features. LOFrUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 153 BIG OCHOPEE MONROE EVERG CYPRESSCITY CONSERVATION AREA NO.3 lOSERT'S l AKE 51 RAND LOOP ROADM.HWY.94) VAMIAMI TRAIL ( US HWY. 41) MIAMISWAMP ... PINECRE. CORAL lABLES 4 ... SLOUGH -4 40 BISCAYNE BAY N < CONT.; 2 ROAD ROCKY HOMES.AO PA....ox/ GLADES ELLIOTT GULF KEY OF O ~ MEXICO ' - 0 RESEA»CH 4- CEN.1 ROAD ,% 4 OLD RHODES '% KEY OLD INGRAHAM Hwy. .. 4 1 m KEY LARGO FLAMINGO 0.8. 16 20 74 FLORIDA BAY .A in Krn Figure 2.-- Map of the study area in southern Florida showing geographical features. 154 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) NY 6 37 9 8 26 10 J6 9 N 1 n36 29 14 15 1 28 27 26 25 , 18 35 20 77 21 35 3 19 0.8 16 70 2. ..1. I. .m Figure 3.-- Major inland waters and drainages of southern Florida: (1) Tamiami Canal; (2) Loop Road Canal; (3) Shark Valley Canal; (4) L-67 Canal Extended; (5) L-31 N and L-31 W Canals; (6) Coral Gables Waterway; (7) Snapper Creek (C-2 Canal); (8) C-100 Canal; (9) Black Creek (C-1 Canal), (10) C-102 Canal; (11) C-103 Canal; (12) C-103 N Canal; (13) North Canal; (14) Florida City Canal: (15) L-31 E Canal; (16) Card Sound Canal; (17) C-111 Canal; (18) Homestead Canal; (19) Taylor River; (20) Sweet Bay Pond; (21) Paurotis Pond; (22) Nine-mile Pond; (23) West Lake; (24) Roberts River; (25) North River; (26) Watson River; (27) Shark River; (28) Squawk Creek; (29) Rookery Branch; (30) Broad River; (31) Lostmans River; (32) Dad's Bay; (33) Lopez River; (34) Turner River; (35) Taylor Slough; 36) Shark River Slough; 37) Gum Slough; 38) Roberts Lake Strand; (39) Gator Hook Strand. LOPTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 155 lower Florida Keys and hold fresh or brackish water for part of the year. A large, artificial rockpit, the Blue Hole on Big Pine Key in the Key Deer Refuge, has a diverse fauna that includes Lepomis macrochirus, many cyprinodontids and poeciliids, and the exotic Texas cichlid Cichlasoma cyanoguttatum. It is not clear whether the native species reached the lower keys naturally. Many of these pools are seasonally brackish (pers. observ.; C.R. Robins pers. comm.) and most of the ichthyofauna rather salt tolerant. It is especially probable that the centrarchids were introduced on Bjg Pine Key. The freshwater aquatic communities of southern Florida depend for their existence upon local rainfall and overland water flow, both of which are seasonally and annually variable. Nearly 85% of the 150 cm average annual rainfall arrives during the wet season, May through October (Fig. 4). This variation in rainfall causes the seasonal fluctuation of water levels (Fig. 5) that characterizes southern Florida wetlands (Kushlan 1979a). The annual dry season varies in duration and intensity. During the most severe dry seasons, water depths decrease rapidly, forcing fishes to concentrate in deep-water habitats such as alligator ponds and canals. Fish mortality, caused by predation and oxygen depletion, can be very high during such dry-downs (Kushlan 1974a). Annual variation in air temperatures is not extensive, the means varying less than 10' C from winter to summer (Fig. 6). Frosts occur infrequently in the freshwater marshes, where standing water moderates air temperatures. Freshwater habitats within Big Cypress Swamp and its drainage include alligator ponds, sawgrass marshes, cypress strands and sloughs, and prairies (Craighead 1971). The swamp is dissected by several major canals and highways. The southern portion of the swamp, included in our study area, is hydrologically continuous with and receives surface water flow from areas north of the Tamiami Trail. During the wet season, surface-water flow occurs over the entire land surface of the swamp, as well as through elongated drainages called cypress strands. Flow in the southern Big Cypress Swamp is generally toward the southwest into the headwaters of rivers emptying into the Gulf of Mexico in northwestern Everglades National Park (Fig. 3). The southern Everglades is the southern terminus of the vast freshwater marsh system that formerly extended north to Lake Okeechobee. Much of this area is included within Everglades National Park. The southern Everglades system drains through two major sloughs: the extensive Shark River Slough and the smaller Taylor Slough. The Shark River Slough receives much of its water by managed discharges from the Everglades Water Conservation Areas to the north. Water flows southwesterly into headwaters of the Shark River and other tidal streams, eventually emptying into the Gulf of Mexico and Whitewater Bay. Taylor Slough drains the area south and east of Shark River Slough. Much of its former drainage area has been developed 156 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) 35.0 - 30.0- 25.0- 20.0- P re ci pi ta lio n (C m ) 15.0- 10.0- 5.0- 3 + 4 1 0 3 3 1 4 6 4 6 Month Figure 4.- Mean monthly precipitation regime in southern Florida. Collected at 40-mile Bend, the eastern intersection of Tamiami Trail and Loop Road (Fig. 2) 1941-1979 (N.O.A.A. 1979). LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 157 200.0- 190.0- 180.0- 170.0 - W ol er Le ve l (C m ) 160.0- 150.0 - 140.0- MMJ/46 Mon~h Figure 5.-- Mean monthly water levels (above mean sea level) in Shark River Slough, Everglades National Park: 1953-1977 (Rose 1977). 158 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) 30.0- 28.0- 26.0- Te m pe ra tu re (t ) 24.0- 22.0- 20.0- 18.0- JEMAM;1156#6 Month Figure 6.- Mean monthly air temperatures in southern Florida. Collected at 40-mile Bend, at the eastern intersection of Tamiami Trail and Loop Road (Fig. 1): 1941-1979 (N.O.AA. 1979) LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 159 for agriculture, and waters that once moved through the slough are now intercepted by levees and canals. As a result, Taylor Slough experiences much longer and more frequent periods of droughts than does the Shark River Slough. Waters in Taylor Slough flow southward into Taylor River and other streams that empty into Northeastern Florida Bay. The southern Everglades includes most of the major aquatic habitats found in southern Florida, including marshes, alligator ponds, canals, and solution holes (Fig. 7). Bordering Shark River Slough on the east and Taylor Slough on the north and east is an area of intermittent marsh referred to as rocky gladelands. This area is slightly higher than the two sloughs and so has a very short hydroperiod . Rocky gladelands are usually covered by Muhlenbergia prairie and mixed-species marshes. Water there is held in solution holes, but because the area dries rapidly and frequently, there are few truly permanent aquatic habitats (other than canals) in the rocky gladelands. The rocky gladelands area outside of Everglades National Park has been referred to as the East Everglades in recent years. The eastern coastal ridge is a zone of slightly elevated land east of the Everglades marshes that extends along the Florida Atlantic coast and into Everglades National Park, where it forms Long Pine Key. This ridge is a preferred area for urban and agricultural development, and most of the natural vegetation of pinelands and hardwood hammocks has been destroyed. Transverse glades and springs that originally carried water across the ridge (Kohout and Kolipinski 1967; Thorhaug et al. 1976) have been replaced by canals and smaller ditches that drain water into Biscayne Bay, thus preventing the flooding of farmlands and suburban and urban developments. Some of these canals are also used to move water coastwards from the interior marshes during the dry season to replenish well fields and to prevent saltwater intrusion into the aquifer. Canals and borrowpits created by the removal of limestone are the major freshwater habitats in this highly urbaniZed section of the study area. The freshwater character of most of these canals is maintained year round by salinity dams near the coast, but water levels fluctuate based upon rainfall, movement of waters through the canal system, and the opening of the dams. During the wet season most of our study area is covered by fresh water. For convenience in this study, we have divided the freshwater habitats in our study area into seven major types: Everglades marsh prairies, Everglades sawgrass marsh, Everglades alligator ponds, the Big Cypress Swamp and associated habitats, canals that dissect natural habitats, canals and borrowpits along the eastern coastal ridge, and mangrove streams and ponds along the coasts. Most of the study area is characterized by shallow water (< 1 m deep) that is often shaded by periphyton mats or emergent plants. In the Everglades 160 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) 1. / Figure 7.--Two aerial overviews of the Everglades marsh in Shark River Slough showing the mosaic of habitats: (A) View to the east during the wet season (open areas are marsh prairies); (B) View to the northeast. Crisscrossed lines in the marsh prairies are made by alligator and deer movements through the periphyton mat. LOFrUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 161 marsh, the periphyton community sometimes exceeds the associated macrophytes in biomass and has a great influence on diurnal water chemistry (Swift 1981; Browder 1982). Physicochemical characteristics of such shallow habitats are highly variable. Even in deep-water habitats such as canals and ponds, these parameters are also variable, especially on a seasonal basis. Fluctuations in dissolved ion levels are measured by the specific conductance of the water. Specific conductance in the southern Everglades ranges from 400 to 700 Bmhos'cm-1 during dry periods (Flora and Rosendahl 1981). In very dry years, when brackish water intrudes into these usually freshwater habitats, the specific conductance of tidal creeks that drain the -1Everglades marsh rises to 15,000 pmhoscm . Annual trends of specific conductance values in canals and in the Big Cypress Swamp are similar to those in the Everglades marsh (Kushlan and Hunt 1979; Waller 1982). Dissolved oxygen values in the Everglades marsh vary from 0.7 to 14.2 -1mgl-1 (=ppm), with similar variation (0.6-12.5 mg1 ) recorded in canals (Waller 1982) and the Big Cypress Swamp (Kushlan and Hunt 1979). Dissolved oxygen concentrations fluctuate diurnally and seasonally. Supersaturation is common during afternoon hours in the warmer months (Kushlan 1979b). The lowest values occur at night and also under dry season conditions, when both shallow- and deep-water areas become deoxygenated and fish kills often result (Kushlan 1974a). Turbidity (JTU) and color (Pt-Co-units) range from 2.0 to 40.0 and 10.0 to 120.0 units respectively in the Everglades marsh (Waller 1982). During wet seasons in the Big Cypress Swamp, turbidity varies from 5.0 to 15.0 JTU and color from 10.0 to 40.0 units. Conditions during dry season fish kills greatly increase turbidity to 165 JTU and color to 85-380 units in the swamp. The hue of such waters changes from slightly brown to green (Kushlan and Hunt 1979). The waters are slightly basic and pH is fairly constant among seasons and habitats, ranging from 7.0 to 8.5 in the Everglades marsh (Waller 1982) and from 7.1 to 8.4 in the Big Cypress Swamp (Kushian and Hunt 1979). Diurnal variation in pH is normally quite low. Concentrations of most major ions in the Everglades marshes (Waller 1982) and in the Big Cypress Swamp (Kushlan and Hunt 1979) are considerably higher during the dry season than in the wet season (Table 1). Major ion concentrations in Everglades canals are similar to those reported from marsh stations (Waller 1982). Trace element concentrations for Everglades marsh stations and for the Big Cypress Swamp are presented in Table 2. Nutrient concentrations at Everglades marsh and canal stations (Flora and Rosendahl 1982) and in the Big Cypress Swamp (Kushlan and Hunt 1979) are generally low but do vary seasonally (Table 3). Dry season values for all nutrients are much greater than wet season values. Ammonia is the dominant 162 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) Table 1. Major ion concentrations (mg'1-1) at Everglades freshwater marsh stations (Waller 1982) and in Big Cypress Swamp (Kushlan and Hunt 1979) during wet and dry seasons. Fish kill data are from a Big Cypress Swamp pond during dry season (Kushlan 1974a). Ion and Season Everglades Marsh (range) Big Cypress Swamp Potassium Wet 0.0- 6.4 0.6 Dry - - 1.9 Fish kill - - Calcium Wet 25.0- 98.0 34.0 D ry 26.0-173.0 56.0 Fish kill - - 86.0 Magnesium Wet 0.5 - 12.0 1.6 Dry 0.7- 20.0 2.9 Fish kill - - 5.1 Sodium Wet 4.4- 58.0 7.6 Dry 4.8-166.0 20.0 Fish kill - Chloride Wet 7.0-140.0 11.0 Dry 9.0-400.0 29.0 Fish kill - - 60.0 Sulfate Wet 0.0-130.0 0.0 Dry 0.0-130.0 0.8 Fish kill - - 34.0 Bicarbonate Wet 48.0-442.0 - Dg 98.0-534.0 - Fish kill - LOFIUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 163 Table 2. Average and maximum concentrations (mg'1-1) of trace elements in water in Everglades National Park, 1959-1977 (Waller 1982), and the range of concentrations measured in the Big Cypress Swamp (Kushlan and Hunt 1979). Everglades National Park Big Cypress Swamp Trace element Average Maximum Range Aluminum 215.0 4700.0 70.0-190.0 Arsenic 4.2 20.0 0.0- 10.0 Cadmium 1.5 35.0 - - Chromium 2.0 20.0 00- 00 Copper 2.7 14.0 0.0- 0.0 Cobalt 0.9 10.0 Iron 723.0 9500.0 50.0-220.0 Manganese 28.0 260.0 0.0- 0.0 Mercury 0.4 6.7 - - Nickel 5.8 41.0 - Lead 16.0 190.0 0.0- 0.0 Lithium - - 0.0- 20.0 Zinc 27.0 100.0 10.0- 20.0 164 BULLErIN FLORIDA STATE MUSEUM VOL. 31(4) Table 3. Nutrient concentrations (mgl.1) in the Everglades freshwater marsh and canal system (Flora and Rosendahl 1982) and the Big Cypress Swamp (Kushlan and Hunt 1979) during the wet and dry seasons. Values for the fish kill refer to measurement from a Big Cypress Swamp pond during the dry season (Kushlan 1974a). Parameter and season Everglades marsh Canal Big Cypress Swamp Ammonia Wet 0.02 - 0.24 0.01 - 0.82 0.02 Dry 0.50 - 1.60 0.06 - 1.10 0.02 Fish kill - Nitrate + Nitrite Wet 0.00 - 0.08 0.01 - 0.47 0.01(NO,); 0.10(NOO Da 0.00 - 0.43 0.02 - 0.49 0.017(N67); 6.10(N6~) Fish kill 0.12(NO~; 2.0(NO3) Total Nitrogen ' Wet 053 -2.31 1.00 - 4.08 0.87 Dry 0.57 -13.00 1.10 - 3.10 0.87 Fish kill - - Orthophosphate Wet 0.00 - 0.020 0.00 - 0.110 0.00 Dry 0.001- 0.107 0.004- 0.013 0.08 Fish kill - 13.00 Total Phosphorus Wet 0.00 - 0.04 0.010- 0.036 0.15 Dry ,, 0.002- 0.20 0.013- 0.260 0.90 Fish kill - Total Carbon Wet 42.00 -101.00 4.40-75.00 Dry 47.00 -136.00 48.00-98.00 Fish kill - - Total Organic Carbon Wet 1.00 - 62.00 16.00-50.00 Dry 4.00 - 73.00 19.00-49.00 - Fish kill - LOFIUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 165 inorganic nutrient; concentrations of orthophosphate and total phosphorus are quite low because of plant assimilation and binding to limestone substrates (Waller 1982). A detailed study of a Big @press Swamp alligator pond during a dry season fish kill found outstandingly high concentrations of all major ions and nutrients (Kushlan 1974a; Kushlan and Hunt 1979) (Tables 1 and 3). Such abnormally high values result from several factors related to the dry season, including concentration due to reduced water volumes, rapid decomposition of animal and plant material, and the reduction of normally bound compounds in bottom sediments during anaerobic conditions (Kushlan and Hunt 1979). In general, water quality parameters and ionic and nutrient concentrations exhibit significant seasonal fluctuations with relation to the wet season-dry season cycle in southern Florida. For much of the year, most natural freshwater habitats are characterized by alkaline pH, low turbidity and color, relatively low nutrient levels, and diurnally fluctuating dissolved oxygen levels. Major ions include chloride, carbonate, calcium, sulfate, and sodium. Dramatic increases in ionic and nutrient concentrations occur during the seasonal dry- down. Everglades canals exhibit water quality characteristics and chemical constituents that are similar to those of natural habitats in the study area. Characteristic plant communities of each habitat type in the study area have been described by Davis (1943), Craighead (1971), and Olmsted et al. (1980). The periphyton community has been studied by Van Meter (1965) and Browder (1981; 1982). Marsh prairies of the Everglades include a diverse array of single- and mixed-species plant associations, on deep peat substrate in the Shark River Slough and on marl in Taylor Slough and the rocky gladelands (Fig. 8). Marsh prairies in Shark River Slough are dominated by spikerush (Eleochads cellulosa) or beakrush (Rhynchospora traqi), and maidencane (Panicum hemitomon) is also locally common. Spider lily (Hymenocallis latifolia), white water lily (Nymphaea odomta), floating heart (Nymphoides aquatica), pickerelweed (Pontedena lanceolata), and arrowhead (Sagittana lane(folia) are also common in depressions or along airboat trails in the marsh. The characteristic plant of the Everglades, sawgrass (Cladium jamaicense), also occurs in sparse stands in marsh prairies. The interstices between plants in sparsely vegetated marshes are often filled by periphyton-covered bladderwort (Uniculada pwpurea). In Taylor Slough and adjacent uplands, intermittent marshes are dominated by sawgrass, muhly (Muhlenbe,gia jil39 t 7-71 N 1 0 4 17 /6 70 74 Figure 18.- Distribution of Esox nizer and Notemizonus crysoleucas in fresh water in southern Florida. Open symbols signify sight records. 190 BULLETIN FLORIDA SIATE MUSEUM VOL. 31(4) are the only two native species of Notropis. Both species are uncommon in our study area. The taillight shiner has been collected in only five locations in extreme southern Florida. Specimens were collected in an alligator pond in the Big Cypress Swamp (Kushlan 1974a) and were also taken in two out of six years of a study in the Everglades marshes (Kushlan 1980a). Specimens were collected in the Everglades marsh only during a prolonged high-water period (Kushlan 1980a) when conditions f6r the shiner may have been more suitable. We collected it in L-31W Canal, C-1 Canal, and in a mangrove-bordered pond near the headwaters of Taylor River. This last record from extreme southern Florida represents an extension of the range of N. maculatus, as provided by Kushlan and Lodge (1974) and Gilbert (198Ob). To the west of our study area, Carter et al. (1973) collected specimens from canals in the Fakahatchee Strand. Large numbers of taillight shiners have been collected occasionally in northern Everglades canals (Dineen 1974). TVo explanations can be offered for the apparently discontinuous distribution of this species in southern Florida. The small population size of this shiner may enable it to escape detection during routine sampling, and the scarcity of slow-flowing canals, its preferred habitat (Kushlan and Lodge 1974), may limit its occurrence. 14. Notropis petersoni Fowler - coastal shiner (I) VS 5*, 10, 25; CS 81, 82, 112 Figure 19 The coastal shiner is a widespread but uncommon fish in southern Florida. It has been recorded from Lake Okeechobee (Ager 1971) and the Caloosahatchee River (Gunter and Hall 1965) but has not been collected in the St. Lucie River (Gunter and Hall 1963a) or in the northern Everglades (Dineen 1974). M petersoni was collected in only four of six years of a previous study in the southern Everglades (Kushlan 1980a), during which sizable collections of the coastal shiner were made. Kushlan and Lodge (1974) noted that, although it was the most numerous Notropis species in southern Florida, it varied in year-to-year abundance. This variation is well illustrated by the absence of N. petersoni m the samples from Shark River Slough taken during our study period, despite extensive collecting. We do not understand the reasons for this variation in numbers and distribution, but its periodic abundance must be related to irregularly favorable environmental conditions that allow the species to multiply and disperse rapidly. We collected several large series of N. petersoni during the present study in Taylor Slough, from a habitat atypical of the Everglades, where water cascaded over a wooden structure to form a pool. A school of shiners gathered at the head of the pool in the current whenever the water flowed in the wet season. They were not present when water flow ceased during the following dry LOFIUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 191 Notroph marulatuu' Netropis #firrioni m Erint,zon wrf/'a & N A A A 0 1 0 4 8 17 16 70 74 Figure 19.-- Distribution of Notropis maculatus, Notropis petersoni, and Erimyzon sucetta in fresh water in southern Florida. Open symbols signify sight records. 1 - Kushlan and Lodge (1974); 2 = Edward Rutherford (pers. comm.). 192 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) season. We also collected coastal shiners below a water control structure in L- 31W Canal when water flowed swiftly over the structure. The records of coastal shiners in the southern Everglades represent range extensions for this species as given by Carr and Goin (1955), Stevenson (1976), and Swift (198Ob). CATOSTOMIDAE - suckers 15. Enmyzon sucetta (Lacepede) - lake chubsucker (I) VS 1, 2, 5, 7, 8, 10, 25, 26, 28, 38, 39 Figure 19 The single species of catostomid in southern Florida is widespread but varies in abundance according to its habitat . Erimyzon sucetta occurs in all habitats in the southern Everglades and Big Cypress Swamp but is most common and attains its greatest size in canals and borrow pits. In the southern Everglades, adult chubsuckers normally inhabit the open waters of alligator ponds. We have taken adults in the marsh prairies primarily during spring when both sexes were in reproductive condition. It appears that adults move into the marshes to spawn. Juvenile chubsuckers are found in marsh prairies, sawgrass marshes, and canal edges, where they are especially abundant from April to July. However, we also collected juveniles at other times of year. In the northern Everglades, Dineen ( 1974) found juvenile E sucetta nearly year- round, which indicates a lengthy spawning period at the southern terminus of its range. The lake chubsucker usually occurs in small schools that move slowly about the bottom of ponds and canals grubbing for food. It is comm6n to observe bluegills (Lepomis macrochirus) following the chubsuckers , presumably to capture prey disturbed by their actions. Although we collected E sucetta from all freshwater habitats throughout southern Florida, there are areas within this region where chubsuckers were quite uncommon. Despite much sampling in Shark River Slough, E sucetta was common only in the northern part of the slough. We did not find it throughout much of the southern Big Cypress Swamp or in the East Everglades. It is our impression that E sucetta is best adapted to stable, deep- water areas such as canals and may not be as successful in areas having shorter hydroperiods. The known range is larger than that shown by Wall and Gilbert (1980). LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 193 ICTALURIDAE - bullhead catfishes 16. Ictalums natalis (Lesueur) - yellow bullhead (I) VS 2, 3, 4, 6, 7, 8, 9, 10, 14, 15, 16, 17, 19, 23, 24, figure 20 25,26,29,30,31,33,38. This is the most common catfish in the southern Evergia¢les. We collected it in marsh prairies, sawgrass marshes, alligator ponds, headwater streams, and cypress swamps. In the northern Everglades, Dineen (1974) found I. natalis to be more common in canals than in the Everglades marsh. In the southern Everglades, the reverse appears to be true. The yellow bullhead was not common in headwater rivers where it appears to be replaced by two species of afiid catfishes. In those habitats, we normally took L natalis among the mangrove roots or submerged vegetation at the edge of the stream, while the ariids always occurred near the bottom in mid-channel. Like the Florida gar, the yellow bullhead exhibits seasonal movements among habitats in the southern Everglades. During high-water periods, the catfish disperse throughout the marsh system and are found in the sawgrass marshes and prairies. With the decline in water levels during the dry season, yellow bullheads concentrate in large numbers (up to several hundred per pond) in alligator ponds. L natalis is better equipped than many Everglades fishes to survive the low oxygen conditions which accompany dry-down because its hemoglobin can efficiently load oxygen at low concentrations (Lodge 1974; LagIer et al . 1977). We often observed I. natalis swimming about alligator ponds during the dry season in compact, circular masses of individuals. These masses of catfish appear to exhibit synchronized movement (Pearson and Miller 1935). The function of this behavior is not understood, but it appears to be restricted to groups of fish confined in a limited space during the dry season and may somehow function in aiding respiration. Kushian (1974a) observed a similar behavior in Big Cypress Swamp populations of L natalis during the dry season and suggested that the movement might help to circulate oxygenated surface water into the water column where it could be utilized. The subspecies is probably L n. erebennus. 17. Ictalums nebulosus (Lesueur) - brown bullhead (I) CS 5, 148, 164, 165 Figure 20 We found the brown bullhead in disturbed habitats such as canals but not in the Everglades marsh. Ictalums nebulosus was never abundant in any habitat, and we did not collect it frequently. There appears to be a difference in habitat occurrence between the two bullhead species in southern Florida, the 194 BULLETIN FLORIDA SrATE MUSEUM VOL. 31(4) klaturits nrbillosits m I. N 0 0 4 BIll 70 74 Figure 20.-- Distribution of Ictalurus natalis and Ictalurus nebulosus in fresh water in southern Florida. Open symbols signify sight records. 1 = Hogg (1974). LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 195 yellow bullhead being common in natural situations and the brown bullhead occurring in disturbed habitats. We collected both species in canals, and even there the yellow bullhead generally outnumbered the brown bullhead. Dineen (1974) did not report this distinction in the northern Everglades, instead stating that both bullheads occurred syntopically in canals and marshes. Kushlan and Lodge (1974) remarked that I. nebulosus appeared to be less abundantthan L natatis in southern Florida and that the former occurred mostly in open, muddy-bottomed habitats. Trautman (1957) found that I. nebulosus in Ohio was usually found in deeper, less-vegetated habitats than I. natalis. In southern Florida, canals best approximate such conditions. The subspecies is presumably L n. mannomms, although this species is in need of taxonomic review (C.R. Gilbert pers. comm.) 18. Icmlumspunctatus (Rafinesque) - channel catfish (I) VS 1*, CS 82* Figure 21 The largest ictalurid in southern Florida occurs in Lake Okeechobee (Ager 1971) and ranges southward through the canal system of the northern Everglades (Dineen 1974). In our study area, L punctatus is an uncommon fish despite repeated introductions. The Tamiami Canal, for example, is a Fish Management Area and has received plantings of channel catfish for angling purposes (Florida Game and Fresh Water Fish Commission brochure). I. punctants has also escaped into the canal system near the main entrance of Everglades National Park from a nearby catfish farming operation. We have observed I. punctatus in these canals, and anglers sometimes report catching large specimens from these waters. We have also observed channel catfish in L-67 Canal Extended, which is continuous with the Tamiami Canal and the Conservation Area canals. We took no specimens from the Everglades marsh system, which indicates that this species does not enter marsh habitats. Dineen's (1974) findings in the northern Everglades concur with our evaluation of the habitat of this species. The channel catfish may be more widespread in the study area canals than our data indicate, but effective sampling of its deep- water habitat was difficult. Its range is larger than shown by Glodek (1980). 19. Noturus gyrinus (Mitchill) - tadpole madtom (I) VS 1, 4, 10, 15 Figure 21 The smallest ictalurid in our study area occurred in a variety of habitats, from canal banks to mangrove swamps. It was most common in Everglades alligator ponds and mangrove stream edges among dense submerged vegetation, but even there it was rarely taken in large numbers. In the northern Everglades, Dineen (1974) found N. grinus to be uncommon, 196 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) 0 N 1 04617 16 70 . Figure 21.- Distribution of Ictalurus punctatus and Noturus Rwinus in fresh water in southern Florida. Open symbols signify sight records. 1 = Tabb and Manning (1961). LOFIUS & KUSHLAN: SO. FLORiDA FRESHWATER FISHES 197 occurring primarily in deep marshes. Carter et al. (1973) did not report this species from the Fakahatchee Strand west of our study area. We did not collect specimens of N. gyrinus in the samples from the southern Big C*ress Swamp, and Kushlan (1974a) did not take it during his study of an alligator hole in the swamp. If N. gyn'nus does occur in the Big Cypress Swamp, the population must be small. Our sampling data suggest that N. gyn'nus may be more successful in habitats with long hydroperiods. We collected most specimens in the Shark River Slough which had a sustained period without dry-down during our study. We found few or no N. gyrinus in the East Everglades and Big Cypress Swamp, both areas having shortened hydroperiods. As it is primarily an inhabitant of deeper marshes and canals, the absence of the tadpole madtom from large areas of southern Florida may be the result of reduced hydroperiod in many habitats. CLARIIDAE - labyrinth catfishes 20. Clarias batrachus (Linnaeus) - walking catfish (II) - Exotic VS 1*, 3, 4, 6, 7, 11*, 12, 18, 19, 23, 25, 26, 27, Figure 22 32,34,39 This most widely publicized exotic fish, C batmchus, has been established in Florida for more than two decades. The original stock was imported from Bangkok, Thailand, and escaped from a north Broward County fish farm in 1965 or 1966 (Courtenay 1975). Entering the canal systems, the fish rapidly spread to adjacent areas of the state. Many of the original escapees were albino, but in successive generations, most of the population has reverted to the normal slate-gray coloration. The albino form is now uncommon in the wild. Walking catfish presently range over much of central and south Florida. From the Kissimmee region, C batrachus occurs south to Lake Okeechobee and the St. Lucie River (Courtenay 1975, 1978), and through the Everglades Water Conservation Areas (Courtenay and Robins 1973). In our study area, the walking catfish ranges from canals in the Big CYpress Swamp, across the Tamiami Canal, south through the East Everglades and rocky gladelands, and along the main Everglades National Park road to Flamingo. Recent samples from brackish-water bays and marshes, including those on Cape Sable, have included specimens of C batrachus. This species also occurs in southern Dade County canals, though many were eliminated during a winter fish kill (Miami Herald, 26 December 1979). These data extend the known range of the catfish to the tip of the mainland. C batrachus has thus far become well established only in disturbed situations, such as canals and borrow pits. We rarely 198 BULLETIN FLORIDASTATE MUSEUM VOL. 31(4) Claries.batrachus e 0 0 N 2 0 4 6 17 . 70 74 Figure 22.-- Distribution of Clarias batrachus in fresh water in southern Florida. Open symbols signify sight records. 1 = Mark Hudy (pers. comm.). LOFIUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 199 collected the catfish in natural freshwater habitats in the study area, despite intensive sampling programs. Only in the rocky gladelands, an area of shortened hydroperiod subject to repeated dry-downs, was the catfish common in a natural freshwater situation. The difficult aquatic conditions in this habitat may have given the catfish an advantage over native species there. Courtenay and Miley (1975) expressed concern over the possible impact of walking catfish on native fishes. Because Clanas spawns during the wet season, they suggested that the population might greatly increase during an extended wet period. High water conditions existed in the Everglades from 1977 to 1981, but we have not seen a noticeable increase in walking catfish there. However, we have noted great increases in the abundance of C batmchus in the Big Cypress Swamp, where the increases seem to be positively correlated to the duration and extent of flooding in the swamp. The walking catfish has taken advantage of high-water periods to disperse across temporarily flooded pineland glades, extending its range southward through Everglades National Park (unpubl. data). Following heavy rains, catfish leave the canals to move overland into previously uncolonized waters. This mode of dispersal allows the species to invade new habitats and to rapidly extend its range. The effects of a severe dry season on the ecology of C batrachus are unknown at present. We agree with Courtenay (1975) that during a prolonged drought the walking catfish may adversely affect native fish populations that would already be under stress (Kushlan 19748). C batrachus can breathe air, enabling it to survive the low oxygen conditions accompanying a drought, and its aerial respiration is synchronous. This behavior, and the short time spent at the surface while respiring, may aid in reducing predation by wading birds (Loftus 1979). This combination of adaptations seems to provide Clarias with a great advantage over most native species. However, following the severe drought of 1981 when much of the Everglades marsh dried, there was no observable increase in the numbers or range of C. batmchus in the study area. We have no current evidence that Clarias poses a threat to the integrity of the Everglades marsh ecosystem within Everglades National Park. Within our study area it is most numerous in canals, through which it has rapidly dispersed and in which it has survived cold spells. C batmchus is now a permanent member of the freshwater ichthyofauna of southern Florida, but its conspicuous absence from most natural freshwater Everglades habitats suggests that competition with native species, or other ecological interactions, have thus far inhibited its colonization of those natural habitats. 200 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) ARIIDAE - sea catfishes 21. Ariusfelis (Linnaeus) - hardhead catfish (VI) VS 16, 24 Figure 23 This euryhaline species occurs in a variety of habitats around southern Florida, but it is most abundant in salt and brackish waters. Hardhead catfish penetrate into the freshwater portions of the headwaters of coastal rivers in the southern Everglades but do not enter the marshes. We took Adus felis in gill nets in most of the rivers sampled . A. felis usually entered the gill nets after dark when they were actively foraging. The ranges ofA. felis and Bagre mannus rarely overlapped the ranges of the three ictalurid species, all of which were uncommon in headwater streams. A. felis has been reported from fresh waters in southern Florida in the St. Lucie (Gunter and Hall 1963a) (0.15-0.230/00) and Caloosahatchee rivers (Gunter and Hall 1965) and throughout North River at all seasons (Odum 1971). 22. Bagre marinus (Mitchill ) - gafftopsail catfish (VI) VS 16 Figure 23 We collected a single specimen of Bagre marinus in a gill net in the main channel of Broad River, the only record from fresh water during our study. It was collected in the company of An'us felis but did not approach it in abundance. Odum (1971) had previously collected B. mannus in fresh water in the North River, where it was out-numbered eight to one by A. felis. Additional freshwater records for B. man)ms have come from the Caloosahatchee River (Gunter and Hall 1965). It appears that this euryhaline catfish is an uncommon inhabitant in southern Flofida fresh water, where it occurs only in coastal rivers. However, it is apparently common in coastal fresh water in the Indian River region of central Florida (Gilmore 1977). LORICARIIDAE - armored catfishes 23. Hypostomus sp. - suckermouth catfish (I) - Exotic Not collected Figure 23 Many species of armored catfish have been imported into the United States from South America by the aquarium trade for use as scavengers and algae eaters. One or more species have escaped into southern Florida waters. We follow Robins et al. (1980) in calling armored catfish from Florida Hypostomus sp. LOFFUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 201 Arius .frlis,0 Bagrr marinus / 1 jyp.St.. .3 1 P. . 0.8 17 16 70 74 Figure 23.- Distribution of Arjus felis, Bagre marinus, and Hypostomus sp. in fresh water in southern Florida. 1 = Courtenay et aI. (1974). 202 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) Hypostomus sp. was reported to be established in the Snapper Creek canal system (Courtenay et al. 1974) and in a west Miami rockpit (Rivas 1965). Additional specimens have been taken from canals near Conservation Area 3 (Courtenay et al. 1974). We did not collect any armored catfish in our study area, indicating that it has not significantly increased its numbers or distribution in southern Florida. Paul Shafland (pers. comm.) suggests that some catfishes collected in our study area belong to the genus Pterygoplichthys, and that most past references to Hypostomus were based upon misidentifications of Pterygoplichthys. The generic identities of loricariid catfishes in southern Florida require further study. BELONIDAE - needlefishes 24. Strongylum manna (Walbaum) - Atlantic needlefish (VI) Not collected Figure 24 The Atlantic needlefish enters fresh water lakes and canals in southern Florida (Ager 1971; Dineen 1974) and is the North American belonid that most commonly enters fresh water (Burgess 198Oh). It had previously been reported from fresh water in extreme southern Florida in canals (Kushlan and Lodge 1974) and in the North River (Odum 1971; Tabb et al. 1974). We observed dozens of needlefish in the coastal rivers during our study. It is possible that S. marina and S. nomm may have occurred among the groups of needlefishes that we observed, but S. timucu was the only needlefish that we captured. 25. Strongylura notata (Poey) - redfin needlefish (VI) Not collected Figure 24 The sole record of S. notata from fresh water in our study area was from the North River during 1966 (Tabb et al. 1974). The only previous record of this species in fresh water (0.250/00) in southern Florida was of two specimens collected in the St. Lucie River (Gunter and Hall 1963a). However, Gilmore (1977) found S. nomta to be abundant in freshwater tributaries of the Indian River area of central Florida. As mentioned in the previous account, we were unable to collect many of the needlefishes that we observed, so we may have missed this species. Although Strongylura species penetrate fresh water in southern Florida, they are restricted to the coastal canals, tidal rivers, and pools, and apparently do not enter the bordering marshes. LOFrUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 203 Sfrengy/ira /i'muri A N , r 04812 16 70 24 Figure 24.-- Distribution of Stronzylura marina, Strongylura notata, and Stronmylura timucu in fresh water in southern Florida. Open symbols signify sight records. 1 = Odum (1971); 2 = Tabb et aI. (1974). 204 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) 26. Strongylura timucu (Walbaum) - timucu (VI) VS 16, 24 Figure 24 This common needlefish apparently enters fresh water in coastal canals and rivers around southern Florida. It has been collected in fresh water in southeastern Dade County canals (Belshe 1961), in the North River (Odum 1971), and in the northern Ten Thousand Islands region (Kushlan and Lodge 1974). We collected the timucu in gill nets and in rotenone samples in Taylor and North rivers. Needlefish in these rivers occurred either alone or in small groups near the water surface, although on occasion we observed groups of several dozen. Though we did not collect S. timucu in all river samples, 6ur observations lead us to believe that it probably enters fresh water in most coastal areas of southern Florida. CYPRINODONTIDAE - killifishes 27. Adinia xenica (Jordan and Gilbert) - diamond killifish (VI) VS 3, 7*, 8, 16 Plgure 25 This euryhaline killifish commonly occurs along the Gulf coast of Florida, whefe it tolerates salinities ranging from fresh to hypersaline (Springer and Woodburn 1960; Tabb and Manning 1961). In our study area, it was most abundant in brackish water (Tabb and Manning 1961; Odum 1971), but also occurred in fresh water in the mangrove zone (Tabb and Manning 1961: Odum 1971) and in the southern Everglades (Kushlan and Lodge 1974). Hastings and Yerger (1971) presented data on the life history and ecology of this species in Florida. A. xenica is an uncommon fish in fresh water in the southern Everglades. Although we collected it along the length of the Shark River Slough from Tamiami Trail to the headwaters area, the number of specimens taken was never large. In collections made in the Shark River Slough, the numbers and distribution of this species were quite variable, and the species did not appear in repetitive samples for many months in a row. A. xenica apparently does not occur regularly to the north in the Everglades Water Conservation Areas, because neither we nor Dineen (1974) have ever collected it there despite extensive sampling. In southern Florida, we collected A. xenica in a variety of freshwater habitats. In the Everglades it occurs in the densely vegetated marsh prairies and in road culverts connecting marsh habitats. A. xenica seenned to be most common in mangrove-lined pools and streams in the headwaters region. We collected our largest series of specimens from such habitats. LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 205 Adinia xr" " " s Gyprinodon.·uarit·Kiliu3 m Floridirlithys mrpie & . 0 N 0 A 0 . 6 17 16 70 74 Figure 25.- Distribution of Adinia xenica, Cyprinodon variegatus, and Floridicht!tvs carpio in fresh water in southern Florida. Open symbols signify sight records. 1 = Tabb and Manning (1961). 206 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) The diamond killifish is a species with a limited distribution in fresh water in southern Florida. Most commonly found in mangrove regions, it is also a permanent but uncommon member of the freshwater ichthyofauna of the southern Everglades. The factors that limit its numbers and distribution in southern Florida fresh waters are unclear. 28. C>pn'nodon van'egams Lacepede - sheepshead minnow (VI) VS 1, 2, 3, 6, 7, 8, 9, 10, 11, 13, 14, 16, 17, 19, Figure 25 20,22,24,31*,34,35 The sheepshead minnow occurs along both coasts of·Florida in brackish and fresh waters. It is a widespread and locally common member of the southern Everglades fish community in both Shark River Slough and Taylor Slough. C van*ams als6 occurs in prairies in the Big Cypress Swamp and in the mangrove pools and marshes in the headwaters region. It is especially abundant in the shallow marshes bordering the headwaters of coastal rivers. Johnson (1974) provided a thorough diagnosis of this species. In the southern Everglades, C vanegams is most numerous in shallow areas, free of dense vegetation, with marl or rocky substrates. Marshes of the East Everglades, rocky gladelands, road culverts, and canal edges best characterize its habitat. The sheepshead minnow is uncommon in heavily vegetated marsh prairies and sawgrass marshes. In the southern Everglades small groups of sheepshead minnows move slowly about the bottom, their pale body color blending well with the limestone or mari substrate. Like certain other killifishes, C variegatus often buries itself in the substrate when threatened. This behavior, in addition to its coloration, probably aids in reducing predation. Sexual differences are apparent in sheepshead minnows, and we often observed brilliantly colored males defending their nests during the long breeding season from January to October. A thorough description of the breeding biology and behavior of C vanegants in southern Florida has been provided by Raney et al. (1953). Odum (1971) discussed the fluctuation of fish populations in the North River and found that this species was greatly outnumbered by Floridichthys ca,pio. The opposite situation was described by Tabb et al. (1974) from the same river, several years earlier. In our sampling of North River, C variegatus was very numerous in the freshwater sections, but we found few F. catpio. Apparently, C variegatus varies in abundance from year to year in the headwaters region, and the same may be true in the Everglades and Big Cypress Swamp (Kushlan and Lodge 1974). The sheepshead minnow is uncommon in fresh water in the northern Everglades region, rarely occurring in samples from the Everglades Water Conservation Areas (Dineen 1974) or LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 207 from Lake Okeechobee (Ager 1971). Christensen (1965) reported C v. hubbsi from southern Florida as far south as the Loop Road (S.R. 94), but these specimens were reassigned to C v. variegams by Johnson (1974). Johnson (1974) did find evidence, for a distinct south Florida race. Martin (1972) discussed factors determining local distribution of C vanegatus in Texas. He collected it in areas characterized by shallow water, sparse stands of rooted vegetation, minimal wave action, and salinities greater than 100/00. It was frequently absent from similar situations at salinities Jess than 100/00. He concluded that the absence of C vaiiegamsin lower salinity waters was probably due to competitive exclusion by centrarchids and other primary freshwater fishes. The habitat he described was similar to .that inhabited by this species in southern Florida fresh water. However, there it.is normally sympatric with five species of Lepomis, Microptents salmoides, Ictalums natalia, and other primary species. In the southern Everglades, primary freshwater fishes do not appear to limit the establishment of C vadegams in fresh water. Martin's (1972) conclusions have also been disputed by Christensen (1965) and Johnson (1974), both of whom found positive associations of centrarchids with C variegatus. Johnson ( 1974) proposed that a combination of limiting factors, including physiological stress in fresh water, may limit the distribution of C van*atus in Florida fresh water. Our observations tend to support his contention. C van*atus is a permanent and locally common member of the southern Florida freshwater fauna. It is most abundant in pools and marshes in the headwaters region, where it becomes concentrated during seasonal dry- downs and serves as a major prey for wading birds (Ogden et al. 1976). 29. Floridichthys carpio (Gunther) - goldspotted killifish (VI) VS 16 Figure 25 The goldspotted killifish is a common inhabitant of shallow brackish and saltwater bays along both coasts of southern Florida (Briggs 1958). It is uncommon in southern Florida fresh water, occurring only in pools and rivers in the mangrove zone. We collected a series of F. camio in a rotenone sample from a mangrove-lined freshwater pool along the North River. F. camio had been previously collected from fresh water in the North River area by Odum (1971) and Tabb et al. (1974). As discussed in the previous species account, the numbers of F. carpio seem to fluctuate dramatically in fresh water. Unlike C. variegatus, which it closely resembles, F. carpio does not enter the Everglades marsh system. Foster (1967) provided a summary of its coloration and breeding behavior in Florida. 208 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) 30. Fundulus chrysotus (Gunther) - golden topminnow (II) VS 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17, 18, Figure 26 19,20,21,22,24,25,26,28,29,30,31,32,33,35 The golden topminnow is the most abundant and widespread species of Fundulus in fresh water in southern Florida. It occurs in the shallow marshes surrounding Lake Okeechobee (Ager 1971) and is numerous throughout the Everglades Water Conservation Areas (Dineen 1974), We collected F. chlysoms in all freshwater habitats in the southern Everglades and Big Cypress Swamp and found it to be one of the most numerous fishes in these areas. F. chgsotus is most abundant in heavily vegetated marsh prairies and in alligator ponds in the southern Everglades, but the largest specimens usually occur in canals and headwater streams. F. chlysotus inhabits the upper levels of the water column, usually alone or in small groups, but never in large schools like some killifishes. ThOugh found primarily in fresh water, the golden topminnow does enter brackish water and exhibits a tolerance for high salinities. Miller (1955) reported no evidence for its occurrence in saline waters, but Kilby (1955) collected F. chrysotus at salinities of 15.0-24.70/00 along the Florida Gulf coast. Kushlan (1973a) found differing responses to dry-down between F. chlysotus and F. confluentus, in which the former retreated to deeper waters such as alligator ponds while the latter species remained in the drying marsh. He suggested that these behavioral differences may be related to reproductive differences between the two species. F. confluentus lays resting eggs (Harrington 1959) and may have remained in the marsh to spawn, whereas F. chgsoms is not known to possess this capability. During our study, we collected fry of F. chiysotus from recently reflooded marshes in the company of fry of F. confluentus, suggesting that the golden topminnow may also be able to lay eggs capable of surviving a short dry-down. Golden topminnows exhibit sexual dichromatism in the southern Everglades. All males are marked with red spots on the body and unpaired fins, in addition to the bars and golden spots mentioned by other authors (Brown 1956; Eddy and Underhill 1978). All females lack the red spots and bars. Occasional melanistic specimens of both sexes occurred in our samples but were not as common as reported by Dineen (1974) from northern Everglades collections. Foster (1967) provided a summary of the coloration, ethology, and life history of this species. LOPTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 209 Fundul!,3 .hysolus O N 0 0 0 4 0 17 1. 70 7. Figure 26.- Distribution of Fundulus chrysotus in fresh water in southern Florida. Open symbols signify sight records. 210 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) 31. Fundulus confluentus Goode and Bean - marsh killifish (VI) VS 1, 2, 3, 4, 7, 8, 10, 11, 13, 14, 15, 16, 17, 18, Figure 27 19,20,21,22,24,26,28,31,32,33,34 This euryhaline killifish is one of the most abundant brackish-water fishes in southern Florida (Tabb and Manning 1961) and is also widespread throughout the freshwater areas. F. confluentus ranges through the southern Everglades and Big Cypress Swamp. It is most abundant in the mangrove-lined creeks, pools, and marshes of the headwaters region. In the southern Everglades, the marsh killifish is the second most common Fundulus, but it never approaches F. chlysoms in abundance in fresh water. In the northern Everglades, F. confluentus occurs in very limited numbers (Dineen 1974). We collected the marsh killifish in a variety of freshwater habitats, including cypress swamps, marsh prairies, road culverts, and along canal banks. Like Cypnnodon vanegatus, it is most numerous in shallow waters over a pale substrate. F. conjluentus also exhibits burying behavior when threatened. Harrington (1959) showed that F. confluenms eggs were capable of surviving a lengthy dry-down, hatching soon after reimmersion in water. This mechanism enables the killifish to survive the droughts that occur seasonally throughout its southern Florida range. Similar mechanisms have evolved among many South American killifish that inhabit areas having short hydroperiods (Myers 1942). This capability may help to explain the abundance of the marsh killifish in the East Everglades, rocky gladelands, and headwater marshes, all of which are areas subject to frequent and prolonged dry-downs. In southern Florida F. confluentus exhibits sexual dichromatism, which differs from descriptions by Eddy and Underhill (1978) and Stevenson (1976). Males are dark with narrow, pale bars on the flanks and light spots on the fins, instead of the series of dark, lateral bars described by Stevenson (1976). The unpaired fins of the males have yellowish-orange borders. Females possess black spots on the body and a black ocellus on the posterior rays of the dorsal fin, but they also exhibit a series of black lateral bars on a pale backgrOund. Neither of the abovementioned authors reported the lateral bars on the female. Brown (1957) and Foster (1967) examined material in which the markings agreed with our specimens. The subspecies is F. c. confluentus. 32. Fundulus gmndis Baird and Girard - gulf killifish (VI) VS 10, 11, 16, 24 Figure 27 The euryhaline gulf killifish is one of the largest species of Fundulus in southern Florida, where it is a common inhabitant of brackish and salt waters. It enters fresh water in southern Florida only in coastal regions. F. grandis had previously been collected from fresh water in our study area by Odum (1971) in LOFIUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 211 Fundulus confium/us / Fundulus grandis m Fundulus lineolatus a Fundulus seminolis * Fundulus aimilis X lf. N 0.1 17 16 20 7. Figure 27.-- Distribution of Fundulus confluentus, Fundulus grandis, Fundulus lineolatus, Fundulus seminolis, and Fundulus similis in fresh water in southern Florida. Open symbols signify sight records. 1 = Tabb and Manning (1961); 2 = Relyea (1975). 212 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) the North River and from the area of Nine-mile Pond by Tabb and Manning (1961). We collected freshwater specimens of F. grandis in rotenone samples from pools along North and Taylor rivers, in a coastal marsh, and along the margin of a borrowpit. Relyea (1975, 1983) stated that there seemed to be no records for this species along the extreme southwestern coast. Relyea's conclusion was probably the result of little collecting effort in that region, because the range of F. grandis in southern Florida does not appear to be disjunct. F. grandis is actually Common in coastal streams and pools bordering the southern Everglades. It does not, however, occur in the Everglades freshwater marshes and most likely enters fresh water only in headwater creeks and coastal canals. This species has been found to produce eggs capable of withstanding desiccation (Harrington 1959), an adaptation that may help it to cope with seasonal dry-downs in coastal marshes. Our data fill.in the distributional hiatus of the gulf killifish as mapped by Burgess and Shute (1980). The subspecific identity of our material is unclear because the study area forms the boundary between the ranges of F. g grandis and F. g. saguanus as delineated by Relyea (1983). 33. Fundulus seminolis Girard - Seminole killifish (II) VS 1*, 3, 10, 11, 14, 26*, 28, 35 Figure 27 The only Fundulus endemic to Florida, F. seminolis is the largest killifish in the Everglades marsh. In southern Florida, it ranges from Lake Okeechobee (Ager 1971) and the Caloosahatchee River (Gunter and Hall 1965), southward through the canals of the Everglades Conservation Areas (Dineen 1974). Carter et al. (1973) collected F. seminolis to the west of our study area in canals in the Fakahatchee Strand. We collected specimens of Seminole killifish from canal edges in the Big Cypress Swamp and southern Everglades, along the margins of several rockpits, and in a sample from a marsh in Taylor Slough. It had previously been collected from culverts along the southern part of the main park road by Tabb and Manning (1961). Although reported from Shark River Slough by Kushlan and Lodge ( 1974), we did not collect F. seminolis there during the present study. From 1976 to 1982, we saw only one school of these fish near the headwaters region of the slough. In contrast, in 1969 and 1970, the Seminole killifish was taken frequently along the length of the slough (Kushlan 198Oa), illustrating that the numbers and distribution of F. seminolis fluctuate over time. In April 1983 following a two year period of record high water levels in Shark River Slough, we observed Seminole killifish in the upper portion of the slough for the first time. Collection data from the southern EvergladeS indicate LOFIUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 213 that this species may inhabit Shark River Slough only during extended periods of high water levels. F. seminolis is most abundant in shallow, open-water areas over light substrate, the habitat typically found along canal and rockpit margins. Its pale coloration makes it difficult to observe and probably provides protection against predation. F. seminolis is the only freshwater Fundulus in the Everglades region to travel in schools, a behavior that may be related to the open character of its habitat. DuRant et al. (1979) recently presented life history data for this species in central Florida. Our distributional data for F. seminolis extend the range given by Stevenson (1976) and Gilbert ( 1980c) to the limits of fresh water in southern Florida. 34. Fundulus similis (Baird and Girard) - longnose killifish (VI) VS 16 Figure 27 Relyea (1983) placed F. similis in the synonomy of F. majalis; we continue to use the name Fundulus similis here to be consistent with Robins et al . ( 1980). F. similis is euryhaline and typically inhabits shallow estuaries, salt marshes, and lagoons (Briggs 1958; Relyea 1983). It rarely enters fresh water. We collected a single specimen of F. similis from a pool along the North River and took several specimens from fresh water in a tidal marsh along C-111 Canal. These represent the first freshwater records for this species in southern Florida. The only other freshwater record for F. similis of which we are aware is from the coast of east central Florida (Gilmore 1977). The individual from the North River fit the meristic and morphometric formula for F. similis but was atypically colored. It showed a pattern of dark bars along the flanks that were much wider than the interspaces, the opposite pattern of a normally colored specimen. Unfortunately this specimen has been lost. Additional adults were taken from fresh water near C-111 Canal. F. simHis is apparently capable of surviving in fresh water for short periods, but it cannot be considered to be a common member of southern Florida's freshwater fauna. It is much more numerous and widespread in coastal waters where it occurs over a wide range of salinity (Martin and Finucane 1967). Relyea (1975, 1978, 1983) found no specimen records for the southwestern coast of our study area, but this species does occur throughout that region in estuarine habitats. The taxonomic status of the southern Florida population remains unclear and may prove to be at least subspecifically distinct (Relyea 1978; C.R. Robins pers. comm.). 214 BULLETIN FLORIDA SrATE MUSEUM VOL. 31(4) 35. Jordanella flondae (Goode and Bean) - flagfish (II) VS 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, Figure 28 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 29,31, 32, 33,34,35,36 The second species of killifish endemic to Florida (Gilbert and Burgess 198Ob), the flagfish is widespread and locally abundant in southern Florida fresh water. 1 foridae inhabits the shallows of Lake Okeechobee (Ager 1971) and ranges southward through the Everglades Water Conservation Areas (Dineen 1974) into the Fakahatchee Strand (Carter et al. 1973), the Big Cypress Swamp, and southern Everglades (Kushlan and Lodge 1974). The flagfish enters brackish water in the headwaters region where we collected it in salinities in excess of 12.00/00. It had been previously collected in brackish water in our study area by Tabb and Manning (1961) who remarked on the extreme fluctuations in its numbers. J. floridae is present in all freshwater habitats within our study area. We found it to be especially common in the Big Cypress Swamp during low water, at which time the fish become concentrated in road culverts and ponds. In some culverts we observed crowded masses of thousands ofJ foddae jammed together. The reasons for this crowding behavior were not clear, especially in light of the presence of nearby, continuous aquatic habitats where ample space was available. In the southern Everglades, we collected few flagfish in marsh prairies with dense, submerged vegetation. They are more common in sparsely vegetated marshes with loose peat or marl substrates into which they can bury when threatened. In these open marshes, we often observed flagfish in small groups moving along the bottom taking in mouthfuls of sediment. In canals and alligator ponds, we collected J. floridae only along the vegetated margins. Flagfish in all habitats are strictly bottom dwellers. During the spring, we observed nesting flagfish in open marsh prairies in southern Everglades. The larger, more colorful males excavate small depressions in the soft substrate and attempt to attract females to the nest while defending a territory of up to 25 cm in diameter. In one small area of marsh, we counted several dozen nests in May 1978. Foster (1967) summarized the nesting biology ofI jloridae and its behavior in aquaria. Eddy and Underhill (1978) erroneously reported that J. floddae occurred in coastal marshes from Florida to Yucatan. The flagfish was reported from Yucatan by Barbour and Cole (1906), but this record was based upon an incorrect identification. Hubbs (1936) erected a new genus, Gannanella , for the Yucatan fish, which does slightly resemble J. floridae and may be closely related (C.R. Gilbert pers. comm.) LOFFUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 215 jordanella Jtoridae / 0 J - - 2 0 0 048 17 16 70 74 Figure 28.- Distribution of Jordanella floridae in fresh water in southern Florida. 216 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) 36. Lucania goodei Jordan - bluefin killifish (ID VS 1, 2, 3, 4, 5, 6,7, 8, 9, 10, 11, 12, 13, 14, 15, Figure 29 16, 17, 18, 19, 20, 21,22, 24, 25, 26, 27, 28, 29, 30,31,32,33,35,36,37,38 L. goodei is one of the four most numerous fishes in the southern Everglades, rivaled in abundance only by Gambusia atinis, Heterandria fonnosa, and Poecilia latipinna. Bluefin killifish are numerous in the littoral zone of Lake Okeechobee (Ager 1971) and are abundant in all freshwater habitats in the northern Everglades (Dineen 1974), the Fakahatchee Strand (Carter et al. 1973), the Big Cypress Swamp, and the southern Everglades (Kushlan and Lodge 1974). In the southern Everglades, L. goodei is most abundant in densely vegetated marsh prairies that have surface periphyton mats and peat substrates. It is less common in open-water habitats, such as canals and alligator ponds, where we collected it only along vegetated margins. In all freshwater habitats, L. goodei always inhabits dense submerged vegetation which it seems to require for cover. The bluefin killifish occurs in mangrove regions of southern Florida primarily during periods of freshwater runoff (Tabb and Manning 1961; Odum 1971), but it also tolerates brackish water. Kilby (1955) collected L. goodei in brackish water along the Florida Gulf Coast, and we caught specimens in the mangrove zone at a salinity of 12.50/00. Although L goodei occurs within the area of the headwaters of coastal rivers, it is uncommon and appears to be replaced there by its congener, Lucania parva. Unpaired fin coloration in male L. goodei is variable. Both the dorsal and anal fins of a male fish can have the same color, either red or blue, or the dorsal and anal fins may be different in color, with one red and the other blue. 37. Lucania parva (Baird) - rainwater killifish (IV) VS 11, 14, 15, 16, 19, 22, 24, 34 Figure 29 The rainwater killifish inhabits a variety of salt and brackish-water habitats throughout its range (Duggins 198Ob) and is locally common in fresh water in areas of northern Florida (Arndt 1971; Burgess et al. 1977). Relyea (1975, 1983) reported the absence of Atlantic coastal records from central Florida to the upper Florida keys, but we have taken many specimens throughout Biscayne Bay north to Miami. Florida mainland populations extend around the tip of the peninsula and are continuous with the Florida keys population. That gene flow exists among Florida populations is supported by the finding of only minor genetic distances in electrophoretic data from different populations (Duggins et al. 1983). LOFIUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 217 Lurani~·goode' 0 Luran:. par.a Rivulus m"moratus A N OSI 16 70 24 ... in Km Figure 29.-- Distribution of Lucania goodei, Lucania parva, and Rivulus marmoratus in fresh water in southern Florida. 1 = Tabb and Manning (1961). 218 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) In southern Florida, L. parva had previously been taken in fresh water in the Caloosahatchee River (Gunter and Hall 1965), in the North River (Odum 1971), and from a southeastern Dade County canal (Belshe 1961). We collected L. parva in fresh water from every creek, river, and pond sampled in the headwaters region. We also collected freshwater specimens in coastal canals in southeastern Dade county. Odum (1971) found that L. parva was one of the most numerous small carnivores in the North River. It occurred in pools and along the banks where plant cover provided protection. L. parva was very common in the headwaters region during our sampling, greatly outnumbering Lucania goodei and most other killifishes in that area. We found it along the margins of rivers and creeks among mangrove prop roots and in submerged vegetation. In fresh water, L. parva is restricted to the coastal regions. The rainwater killifish rarely enters the southern Eveglades marshes, where it is replaced by Lucania goodei. We collected only three small specimens of L. parva in the fresh water Shark River Slough marshes during five years of sampling. 38. Rivulus mannomtus Poey - rivulus (IV) Not collected Figure 29 R. mannorams is primarily a coastal brackish and saltwater species, first reported from Florida in 1958 (Harrington'and Rivas 1958). It had previously been known only from Cuba. R. mannorams has since been collected only from estuarine mangrove habitats and mosquito ditches along both coasts of southern Florida (Hastings 1969, 1975) and from the Bahamas and the Lesser Antilles (Snelson 1978; Gilbert and Burgess 198Od). Several authors have reported R. mannomtus from our study area, but two (Belshe 1961; Odum 1971) did not report the salinities in which the specimens were collected. Although it appears to be rare, Rivulus does enter the diet of wading birds in southern Florida (Ogden et al. 1976; Frohring and Kushlan unpubl. data). The only verified freshwater record for R. mannomtus in southern Florida was by Tabb and Manning (1961). They also collected it in brackish-water habitats. We did not collect R. marmoratus during our sampling in the estuarine zone. We conclude that it is very rare in fresh water in southern Florida and does not enter the Everglades marsh. LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 219 POECILIIDAE - livebearers 39. Belonesox belizanus Kner - pike killifish (II) - Exotic VS 29,39 Figure 30 This piscivorous livebearer from Central America was introduced into southeastern Dade County canals in the 1950's (Belshe 1961). It had become established near Black Creek by 1957 and has since spread north to Coral Gables (Courtenay et al. 1974) and south to the mangrove marshes around Canal C-111. We collected several Large series of B. belizanus from fresh water in the coastal canals of Dade County, but we have never found it more than 10- 12 km inland from the coast. Some factor appears to restrict B. belizanus to coastal regions in southern Florida. The pike killifish is very tolerant of saline conditions and has been collected from mangrove pools with salinities in excess of 350/00 (Robins and Getter In Robins et al. 1980; Gary Balogh pers. comm). This tolerance has probably aided its dispersal around southeastern Dade County by enabling it to use saline pathways. Belshe (1961) found that B. belizanus was most abundant in deep, narrow canals having dense marginal vegetation. This habitat is abundantly represented by small farm ditches and mosquito ditches near the coast. We collected the largest numbers of pike killifish in such habitats. B. belizanus is locally common in the larger drainage canals where the wide, deep channels are kept free of aquatic vegetation. There the pike killifish occurs only in vegetation along the canal margins. Dense aquatic vegetation provides protective cover and, in turn, affords cover from which it can ambush small prey fishes. When stalking small fishes, the pike killifish remains motionless until the prey is near, then arches its body and springs at the prey, which is swallowed either head or tail first. Belshe (1961) found it to be a voracious predator of small fishes in southeastern Dade County and reported that there was fear that malarial epidemics might occur if the pike killifish significantly reduced the number of small, mosquito-eating fishes. These fears have not been realized, though we have observed very low populations of small fishes, including the usually abundant Gambusia a~inis, in ditches where B. belizanus is common. It seems likely that, considering the diet, habitat, and salinity tolerance of B. belizanus, it will continue to increase its range along the southeast coast. Whether it will colonize inland aquatic habitats is uncertain at this time. 220 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) 8, lonriox brlizan:a I 1 #-.3 N 0817 16 70 74 Figure 30.-- Distribution of Belonesox belizanus in fresh water in southern Florida. 1 = Courtenay et al. (1974). LOFIUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 221 40. Gambusia a~nis (Baird and Girard) - mosquitofish (II) VS 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, Figure 31 16,17,18,19,20,21,22,23,24,25,26,27,28, 29,30,31,32,33,34,35,36,37,38,39 The mosquitofish is the most abundant and ubiquitous fish in southern Florida fresh water (Kushlan and Lodge 1974). It occurs in large numbers in Lake Okeechobee (Ager 1971) and ranges south through the Everglades Conservation Areas (Dineen 1974), the Big Cypress Swamp, and southern Everglades. It is also common in canals along the eastern coastal ridge. We took G. afnis in nearly all the collection sites and from every freshwater habitat type within our study area. The mosquitofish is also widespread and numerous in brackish water (Tabb and Manning 1961; Odum 1971) and may enter waters in southern Florida that are more saline than those inhabited elsewhere in its range (Gunter and Hail 1963a). We have frequently collected and observed G. aBinfs in salt water along the shallow coastal areas and mangrove keys of Florida Bay and Biscayne Bay. In the Indian River area, this species has been collected at 800/00 (R.G. Gilmore pers. comm.). In the southern Everglades, we found G. abinis in alligator ponds, marshes, and canal margins. Although it is common in the densely vegetated marsh prairies, the mosquitofish is more numerous in sparsely vegetated marsh prairies without dense periphyton cover at the surface. In aquarium studies of habitat choice (Casterlin and Reynolds 1977), G. afnis preferred habitat characteristics similar to those we observed in natural situations, except the fish chose darker rather than lighter colored substrates. Maglio and Rosen (1969) found that water temperature was more important than substrate color in determining the distribution of G. a~inis in a pond, but that there was a relationship between reproductive state of females and their choice of substrate color. In the southern Everglades, we commonly took G. affinis over both pale and dark-colored substrates in canals and marsh prairies, indicating that substrate color may not be an important parameter for habitat selection by G. a#inis in our area. The mosquitofish is the most abundant species in canals, swamps, alligator ponds, and in sloughs in the Big Cypress Swamp (Carlson and Duever 1977). It is also numerous in the freshwater pools and streams at the headwaters of coastal rivers. G. amnis is primarily a surface-dwelling fish, small groups moving constantly about the open surface waters. G. a~nis is particularly attracted to surface disturbances and will quickly converge on the site of a disturbance, probably in search of food. In the Everglades, this behavior is peculiar to the mosquitofish, and it is taken advantage of by wading birds that disturb the water surface to attract fish within striking distance (Kushlan 1973b). We have 222 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) Gambusia gfinis Gambusia rh,zophoym m 0 I ..9 N r 1 04817 . 70 74 Figure 31.-- Distribution of Gambusia affinis and Gambusia rhizophorae in fresh water in southern Florida. 1 = Rivas (1969). Marine sites are indicated by 2. LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 223 often observed G. a~nis clustering around alligators , whose movements may stir up prey for the fish. The mosquitofish also peck at the alligators, probably to dislodge flecks of dead skin or parasites. Individual G. a#inis differ in maximum size and coloration in different habitats within our study area. Mosquitofish in the Everglades marsh do not reach the larger maximum sizes of G. affinis from fresh water in coastal canals. Mosquitofish from coastal canals are also darker in coloration and have a darker suborbital bar. As with many poeciliids, female mosquitofish grow considerably larger than the males (Turner 1941). Coloration of the sexes is similar, although a small percentage of males are partially melanistic (Regan 1961). Coastal populations of mosquitofish seem to have relatively higher proportions of melanistic males than inland populations (pers. observ.). An aggressive nature, catholic diet, small size, and ability to survive in foul water (Lewis 1970; Kushlan 19748) all combine with a long reproductive season to make G. amnis the most successful fish in southern Florida fresh water. The well - defined subspecies in peninsular Florida is G. a. holbrooki. 41. Gambusia rhizophorae Rivas - mangrove gambusia (IV) CS 15la Figure 31 In his description of G. rhizophorae, Rivas ( 1969) listed the type locality as Paradise Key, Everglades National Park, but added that the species appears to be restricted to estuarine areas and mangrove swamps. Paradise Key, in Taylor Slough, is occupied by a tropical hardwood hammock (Royal Palm Hammock) surrounded by fresh water. Freshwater records for G. rhizophome from Florida prior to our study were non-existent (Getter 1976; Gilbert 1978a), although records did exist for Cuban fresh waters (Getter 1982). Kushlan and Lodge (1974) thought that Rivas' (1969) collection data were erroneous; we concur. Rivas (pers. comm.) has informed us that he did not personally collect the type specimens, and that he now also believes that the collection data included with the type specimens were probably in error. We collected the first known freshwater specimens of G. rhizophorae at Parrot Jungle, a south Miami tourist attraction, from an artificially maintained stream leading to a brackish- water canal. Small groups were present in the stream at the time of sampling. We did not collect G. rhizophome at any other freshwater site during this study and conclude that it is uncommon in fresh water in south Florida. In aquaria, this species can survive and reproduce in fresh water indefinitely and it reproduces in fresh water in Cuba (Getter 1976, 1982, pers. observ.), so that its natural occurrence in southern Florida fresh water must be limited by factors other than salinity. Getter (1982) presented evidence that the distribution of G. rhizophorae in southern Florida is restricted by its intolerance of cool, winter 224 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) water temperatures. Perhaps, the artificial Parrot Jungle stream maintains higher water temperatures than nearby canals. Incidental to collections made in fresh water in the study area, we also collected G. rhizophome at several new saltwater locales in the upper Florida Keys. The specimens were taken from shallow, protected waters around Rhizophora mangle roots at Elliott, Old Rhodes, and Totten Keys in Biscayne National Park (Fig. 31). The mangrove gambusia is probably present in suitable habitat throughout Biscayne National Park and portions of northeastern Florida Bay in Everglades National Park where, as a Species of Special Concern in Florida (Gilbert 1978a), it is afforded protection from collection and habitat loss. 42. Heterandria formosa Agassiz - least killifish (II) VS 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, Figure 32 17,18,19,20,21,22,23,24,26,27,28,29,30, 31,32,33,34,35,36,37,38 One of the most abundant fishes in the southern Everglades, H. fonnosa occurs throughout southern Florida. It ranges from Lake Okeechobee (Ager 1971) through the Everglades Water Conservation Areas (Dineen 1974), into the Fakahatchee Strand (Carter et al. 1973), the Big Cypress Swamp, southern Everglades, and eastern coastal ridge. The least killifish also inhabits the margins of freshwater pools and streams in the headwaters of coastal rivers. It enters brackish-water habitats in this region but is never numerous there (Tabb and Manning 1961; Odum 1971). We collected the least killifish in all the habitats samples, including cypress swamps, canal margins, sawgrass marshes, and alligator ponds. In all habitats, H. formosa is always associated with dense vegetation. H fonnosa is most numerous in the marsh prairies of the southern Everglades, where it inhabits dense beds of Utricularia spp. under the surface periphyton mat. Only occasionally is it found in more open areas, usually in mixed schools with Gambusia ah?nis. Because of its size, it requires protective cover against predation by most cohabiting fishes. The least killifish seems to be well adapted to dry season conditions in the Everglades marsh. Its small size enables it to remain alive in puddles of water in the drying marsh. Female H. fonnosa attain greater maximum sizes than do males, which are among the world's smallest vertebrates at maturity (Breder and Rosen 1966). LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 225 Y- 1 Hitryondiia form.a . N J 1 00 0 4 8 17 16 20 74 ~~ole in .m Figure 32.-- Distribution of Heterandria formosa in fresh water in southern Florida. 226 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) 43. Poecilia lat*ma (Lesueur) - sailfin molly (VI) VS 1, 2, 3, 4, 6, 7, 8, 9, 10, 13, 14, 15, 16, 17, 18, Figure 33 19,21,22,23,24,25,26,28,29,31,32,33,34, 35,36,37,38,39 The sailfin molly is another widely distributed southern Florida fish, attaining greatest abundance in brackish water. In fresh water, the sailfin molly ranges from the marshes surrounding Lake Okeechobee (Ager 1971) southward into the Fakahatchee Strand (Carter et al. 1973), the Big C*ress Swamp, southern Everglades, and eastern coastal canals. P. lan»:na is very numerous in the mangrove-lined streams and pools of the headwaters and in most coastal canals. P. latipinna is quite common in the southern Everglades marsh, where we collected it in all aquatic habitats. The sailfin molly is most numerous in sparsely vegetated marsh prairies with periphyton-covered marl substrates. The pale body color of the sailfin molly blends well with the substrate in this habitat. Mollies inhabit all levels of the water column, traveling about in small to moderately sized groups while grazing on algal-covered plant stems and bottom materials. Freshwater specimens of P. latipinna attain their largest sizes in canals and alligator ponds. Smaller individuals normally inhabit the Everglades marshes. Sailfin mollies from inland freshwater habitats rarely attain the larger maximum sizes of mollies from brackish-water areas. This habitat-related size difference in sailfin mollies has been noted in other parts of its range (Swift et al. 1977) and may result from a combination of environmental, social, and genetic interactions (Snelson 1982). The sailfin molly is sexually dimorphic and dichromatic. Large males possess high, long dorsal fins marked with black streaks, and caudal fins edged in blue and black. Males spread both these fins during sexual and agonistic displays. In the southern Everglades marsh, it appears that some males never develop the bright colors and large fins of males from other habitats, possibly because they generally do not grow as large. We collected several melanistic sailfin mollies of both sexes during our sampling, but melanism seems to be less frequent in the freshwater populations than in the brackish-water populations in southern Florida (pers. observ.). LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 227 P.·fijia /.lipill. 0 1• , ..r \E M . N 1 0 .. 2 0 4 8 17 16 20 24 Figure 33.- Distribution of Poecilia latipinna in fresh water in southern Florida. 228 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) ATHERINIDAE - silversides 44. Labidesthes sicculus (Cope) - brook silverside (IV) VS 1, 2, 5, 7*, 8*, 10, 11, 13, 21, 22, 24, 26, 27, Figure 34 28,32,35,37,38 L sicculus is primarily restricted to fresh water in southern Florida, where it ranges from Lake Okeechobee (Ager 1971), through the Everglades Water Conservation Areas (Dineen 1974), into the Big Cypress Swamp, the southern Everglades, and eastern coastal canals. We collected L. sicculus in all freshwater habitats in the southern Everglades except sawgrass marshes. In the Big Cypress Swamp, L. sicculus occurs in alligator ponds and deep cypress sloughs. We collected very few specimens in Shark River Slough, although specimens were regularly taken there from 1966 to 1972 (Kushlan 198Oa). L. sicculus is most common in open-water habitats, such as canals, alligator ponds, and borrow pits, where it travels about in small to moderately sized groups. We were often able to record the presence of L. sicculus at a collection site because of its habit of leaping from the water. This behavior is probably an avoidance response to aquatic predators. The ranges of the brook silverside and inland silverside (Menidia betyllina) overlap only in the freshwater streams of the headwater region and in certain coastal canals. L. sicculus is primarily a freshwater silverside occurring inland of the brackish-water zone; Menidia beryllina is abundant in brackish areas, entering fresh water only in coastal regions. Because L. sicculus ranges to the limits of fresh water on the peninsula, its range is larger than that presented by Lee (1980c). The subspecies is L. s. vanhyningi, a well-defined race that ranges well outside of Florida (Lee 198()c). 45. Menidia begllina (Cope) - inland silverside (V) VS 15, 16, 19, 22, 24, 34 Figure 34 The inland silverside is a euryhaline species that ranges in fresh water from Lake Okeechobee (Ager 1971), the St. Lucie (Gunter and Hall 1963a) (0.140/00) and Caloosahatchee rivers (Gunter and Hall 1965) southward along both coasts in mangrove areas (Raney et al. 1953) and canals (Hogg 1976a) to the southern tip of the peninsula. An exceedingly abundant fish in brackish water, M. belyllina is also numerous in freshwater habitats along the headwaters of coastal streams in southern Florida. Large schools of M. beiyllina inhabit the surface waters of streams, pools, and river margins in the headwaters, and we found it at nearly every collection site there. Odum (1971) found M. begllina to be the most abundant fish in the North River system, and LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 229 1-abid„th„ sirruiu, 0 Mmidia beryllina s 2 *6 el ° N 0 0 4 BIll .0 74 Figure 34.-- Distribution of Labidesthes sicculus and Menidia beryllina in fresh water in southern Florida. Open symbols signify sight records. 230 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) the same is probably true for other river systems in southern Florida. We do not believe that Atlantic and Gulf populations are disjunct, as was proposed by Relyea (1983). Although M. belyllina inhabits small streams that enter the southern Everglades marsh, we never collected it in the marsh. In southern Florida, this silverside appears able to penetrate into fresh water only in coastal areas, where it is restricted to canals and riverine habitats. Three recent taxonomic studies of Menidia (Johnson 1975 ; Duggins 1980a; Chernoff et al . 1981) have clarified the identities of Menidia beryllina and M. peninsulae. No subspecific designation has been provided for southern Florida populations ofM. beryllina. CENTROPOMIDAE - snooks 46. Centropomus ens*ms Poey - swordspine snook (VI) Not collected Figure 35 C ens(ferus is apparently uncommon in North American fresh water, where it is limited to extreme southern Florida (Burgess 198Ob). Four specimens collected from freshwater canals in Miami (Rivas 1962) represent the only known records of this snook from our study area. C ensiferus is the smallest snook and has the most restricted occurrence of any Centropomus in Florida (Rivas 1962; Burgess 198Ob). We did not collect it during our sampling of canals and rivers. 47 . Centropomus parallelus Poey - fat snook (VI) Not collected Figure 35 The fat snook ranges from Lake Okeechobee to the southern tip of Florida in fresh water (Rivas 1962; Burgess 19800, but most freshwater habitats within this range are probably unsuitable for it. The majority of freshwater records come from canals along the southeast coast (Rivas 1962; Burgess 19800. We did not collect C parallelus during our sampling, but it seems possible that it may enter fresh water in the coastal rivers that drain the Everglades. LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 231 C¢n¢reemus in#,us 0 C.'trop.mus p..Qll£11. I Cfntrop...5 p..tinatu' I Centrotomus underimalis* Epint·p}d lus ilajara X8-\\Il 1 . - - - 2 3 0 4 " ·16 70 74 Figure 35.-- Distribution of Centropomus ensiferus, Centropomus parallelus, Centropomus pectinatus, Centropomus undecimalis, and Epinephelus itaiara in fresh water in southern Florida. Open symbols signify sight records. 1 = Odum (1974); 2 = Tabb and Manning (1961); 3 = Tabb et al. (1974); 4 = Hogg (1974); 5 = Rivas (1962). 232 BULLETIN FLORIDA SrATE MUSEUM VOL. 31(4) 48. Centropomuspectinatus Poey - tarpon snook (VI) Not collected Figure 35 This species ranges southward in Florida from the Indian River region on the Atlantic coast and the Fort Myers area on the Gulf coast (Burgess 198Od). Freshwater specimens of tarpon snook in southern Florida have been collected in the Caloosahatchee River and in several Miami canals (Rivas 1962). It has also been taken in fresh water in North River (Tabb et al. 1974). We did not collect C pectinams, but it probably occurs in small numbers in coastal freshwater canals and rivers in our study area. The tarpon snook appears to be more common in freshwater habitats in the Indian River region of east central Florida (Gilmore 1977). 49. Centropomus undecimalis Bloch - snook (VI) VS 1, 2*, 22*, 24*, 26*, 27; CS 154 Figure 35 The snook is the most numerous and widespread of the four species of Centropomus in southern Florida (Burgess 198Oe). Snook have been collected in fresh water in Lake Okeechobee (Ager 1971), in the St. Lucie (Gunter and Hall 1963a) and Caloosahatchee rivers (Gunter and Hall 1965), and in the canals of the Everglades Water Conservation Areas (Dineen 1974), the Big Cypress Swamp, and the southern Everglades (Kushlan and Lodge 1974). C undecimalis also enters fresh water in coastal canals (Rivas 1962) and in the rivers and pools of the headwaters region (Tabb and Manning 1961). Both adult and juvenile snook occur in the freshwater areas of coastal rivers in Evergaldes National Park (Odum 1971; Tabb et al. 1974). Snook enter the canal system of the Everglades and Big Cypress areas by following the same routes as tarpon. C undecimalis occurs in several canals in this part of our study area, but at least one canal, L-67 Canal Extended, lost its population in the freeze of 19-20 January 1977. Five large snook died a few days after this freeze, and many months passed before any snook were seen or caught in that canal. Snook are especially sensitive to low temperatures, and mortality caused by winter cold spells is not uncommon in southern Florida (Marshall 1958; Dineen 1974). Most of our distribution records for snook (Fig. 35) are based on sight observations in coastal rivers and canals. C undecimalis is a large, unmistakable Centropomus that is easy to observe with a spotlight during night sampling but is difficult to capture. Snook are more widespread in fresh water than our data indicate, but their relatively low numbers and difficulty of capture resulted in few specimens. LOFIUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 233 SERRANIDAE - sea basses 50. Epinephelus itajara (Lichtenstein) - jewfish (VI) Not collected Figure 35 The largest serranid in southern Florida spends its juvenile stages in shallow, coastal waters where it tolerates a variety of salinities. In the Shark River, McPherson (1970) collected specimens at salinities ranging from 3.20/00 to 15.00/00. lIn these rivers, juvenile jewfish also stray into fresh water. In 1966, a specimen measuring 191 mm was taken in fresh water in North River (Tabb et al. 1974), the first freshwater record for this species. We did not collect jewfish during our sampling, but it may be more common in the freshwater portions of the rivers than the collection records indicate. CENTRARCHIDAE - sunfishes 51. Elassoma evergladei Jordan - Everglades pygmy sunfish (I) VS 2, 4, 10, 15, 30, 31, 35 Figure 36 If. eve,gladei is one of the smallest centrarchids, reaching a maximum length of about 30 mm TL. The Everglades pygmy sunfish ranges widely throughout southern Florida from Lake Okeechobee (Ager 1971) and the Everglades Water Conservation Areas (Dineen 1974), through the Big Cypress Swamp, and into the southern Everglades (Kushlan and Lodge 1974). It occurs in a variety of habitats throughout its range, but in southern Florida we always collected it in dense aquatic vegetation. In the sloughs of the southern Everglades and Big Cypress Swamp, E. evergladei is most common in thick beds of Utn'culatia and Najas and also in dense sawgrass strands. In canals, Kushlan and Lodge (1974) frequently collected it among water hyacinth roots. Although Dineen (1974) collected E evergladei in shallow marshes of 8-25 cm in depth, we found it most often in deeper sloughs and ponds, where dense vegetation was present. The Everglades pygmy sunfish is absent from the more developed parts of the study area (Fig. 36). In northern Florida, Swift et al. (1977) found that E. eve,gladei occurred primarily in stained, soft waters and was rare in clear, unstained, hard waters. In the study area, E. eve,gladei occurs in a variety of water and habitat conditions but is most numerous in the clear, alkaline waters of the southern Everglades. Our collection data extended the known range of this species as shown by B6hlke and Rohde (1980). 234 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) E/ossoma currglad,·i / Elinmranctits Kit}riosits m D- 01.fk N 0 4 1 12 16 70 74 Figure 36.-- bistribution of Elassoma evergladei and Enneacanthus gloriosus in fresh water in southern Florida. 1 = Tabb and Manning (1961). LOFFUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 235 The Everglades pygmy sunfish is abundant near the headwaters of coastal rivers in Everglades National Park, where it occurs in heavily vegetated marshes and stream margins. In dry-season samples from this area, we found large numbers in isolated puddles in the drying marshes, indicating that it may be able to survive in these shallow marshes until reflooding occurs. Male Everglades pygmy sunfish attain a slightly larger size than females in southern Florida. During much of the year, the male retains his spawning colors of a black body marked with blue streaks. This fact suggests an extended breeding season in southern Florida, although the peak of breeding appears to , be in late winter and spring. Redent studies have investigated aspects of the reproductive behavior of E dve,gladei (Mettee 1974) and the effects of population density on community dynamics (Rubenstein 1977) in aquaria. 52. Enneacanthus gloriosus (Holbrook) - bluespotted sunfish (I) VS 1, 2, 4, 5, 10, 22, 26, 28, 32, 35, 38 Figure 36 The bluespotted sunfish is another small centrarchid that is widespread throughout the southern Everglades and Big Cypress Swamp. E gloriosus ranges through the Everglades Water Conservation Areas (Dineen 1974), Lake Okeechobee (Ager 1971), and the St. Lucie (Gunter and Hall 1963a) and Caloosahatchee rivers (Gunter and Hall 1965.). In our study area, we collected E. gloriosus in marshes, cypress sloughs, and alligator ponds in association with thickets of submerged plants. The bluespotted sunfish also occurs in heavily vegetated canals and road culverts, but it is less common in canals of the urbanized east coast (Kushlan and Lodge 1974). We collected the first specimens of E gloriosus from the headwaters region of southern Florida (Fig. 36), in beds of Najas in the feeder creeks. Tabb and Manning (1961) and Odum (1971) did not collect E. gloriosus at their study sites in that region . The bluespotted sunfish, although widespread in southern Florida, is only locally common and rarely as abundant as sympatric Elassoma evegladei. It is much more common in the northern Everglades, as evidenced by the collection of 1021 fish in a 1-acre marsh sample (Dineen 1974). In our sampling of the Everglades Water Conservation Areas (unpublished data), we also found the bluespotted sunfish to be more common than in the southern Everglades marsh. Water levels there are artificially maintained at higher levels for longer periods than in the southern Everglades. Within our study area, the largest nunnbers of E gloriosus occur in canal and alligator ponds that offer more stable water conditions than the surrounding wetlands. It appears that E gloriosus is poorly adapted to the fluctuating water levels and occasional dry- downs of the southern Everglades and is more successful in habitats having longer hydroperiods. This species has a more extensive Florida range than that shown by Lee and Gilbert (1980). 236 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) 53. Lepomis gulosus (Cuvier) - warmouth (I) VS 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, Figure 37 16,17,18,19,21,22,23,24,25,26,27,28,29,30, 31,32,33,34,37,38,39 The warmouth is widespread throughout southern Florida, where it is one of the most abundant centrarchids. Its range extends from the littoral zone of Lake Okeechobee (Ager 1971), through the canals and marshes of the northern Everglades (Dineen 1974), southward into the Big Cypress Swamp, the southern Everglades, and the eastern coastal canals (Kushlan and Lodge 1974). In the Big Cypress Swamp, L gulosus is a common inhabitant of alligator ponds and cypress sloughs. In the southern Everglades, we found the warmouth to be common in marsh prairies and sawgrass marshes during the wet season, retreating to alligator ponds as the waters recede in the dry season. L gulosus is one of the best-adapted centrarchids to the fluctuating water levels of the Everglades. It seems to be the sunfish most tolerant of the low oxygen conditions associated with the dry season and survives after all other centrarchids have died (Kushlan 1974a). Unlike the bluegill (Lepomis macrochims) and redear sunfish (Lepomis microlophus), which inhabit more open waters, L. gulosus is often abundant in densely vegetated marshes. In the shallow littoral zones of ponds and canals, L. gulosus inhabits cavities in the limestone margins. The warmouth is a top-level predator in the southern Everglades marsh, where most bass (Micropte,us salmoides) and gar are excluded by the shallow waters, fluctuating water levels, and thick vegetation. The warmouth is quite common in the pools and creeks of the headwaters region where it occurs in moderately brackish waters. However, Kilby (1955) considered L. guloms to be practically restricted to fresh water, never having collected it in salinities above 1.80/00. We collected specimens at a salinity of 12.50/00, higher than the upper limit reported by Brockman (1974). 54. Lepomis macrochirus Rafinesque - bluegill (I) VS 1, 2, 3, 4*, 5, 7, 8*, 10, 11, 19, 22, 23, 25, 26, Figure 38 27,28,29,32,37,38,39 The bluegill is one of the most abundant centrarchids in the southern Florida canal system, where it is an important food and sport fish. It is the most numerous centrarchid in Lake Okeechobee (Ager 1971) and ranges southward through the canals of the Everglades Water Conservation Areas (Dineen 1974), the Big Cypress Swamp, the southern Everglades, and eastern coastal canals (Kushlan and Lodge 1974). The bluegill is very common in canals and borrow pits that are kept free of dense aquatic vegetation. In older LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 237 Lrpuwa gulesus e 0 . 6 * 0 .. #. 0 N % I 0 0.8. . 20 74 Figure 37.-- Distribution of Lepomis gulosus in fresh water in southern Florida. 238 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) L,pomi. marrorhiru. e -0 .0 . I # 0 N 0 4 1 00 0 0 4 8 12 16 20 1/ Figure 38.- Distribution of Lepomis macrochirus in fresh water in southern Florida. Open symbols signify sight records. 1 = Odum (1974). LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 239 weed-choked canals, adult bluegill occur only in the open-water areas maintained by alligators. Immature specimens occur in the surrounding beds of vegetation. These observations of habitat partitioning by different age- classes agree with those made on the northern subspecies by Werner et al. (1977) and Casterlin and Reynolds (1978). In the southern Everglades and Big Cypress Swamp, we collected adult bluegills mainly in alligator ponds and deeper sloughs, the only habitats free of dense vegetation. In marshes, we collected only small specimens, and these only occasionally. Dineen ( 1974) found that L. macrochims was never abundant in northern Everglades marshes and that the bluegills from the marshes were smaller than those living in canals. In our study area, the bluegill also occurs in pools and creeks in the headwaters region, where we observed it nesting in moderately brackish water. L. macrochirus is sensitive to low oxygen conditions associated with the dry season and is one of the first species to die during a fish kill (Kushlan 1974a). We believe it is this lack of adaptation to seasonal water fluctuations that is responsible for the absence of bluegills from large sections of natural habitat in the study area. During our study of ponds at the Anhinga Trail (CS 112), we repeatedly saw largemouth bass soliciting bluegills for cleaning. This behavior was first described by Sulak (1975) from the same location. We have observed groups of bluegills following alligators as they move through the water and have also seen them follow closely behind foraging groups of Frimyzon sucetta near the bottom. We assume that the bluegills are feeding on prey disturbed by the movements of these animals. The subspecies in southern Florida has been called L m. pwpurescens, but recent evidence indicates that the subspecific name refers to a more northerly population, and that the Florida subspecies is currently unnamed (Felley 1980). 55. Lepomis marginatus (Holbrook) - dollar sunfish (I) VS 1, 2, 3, 4, 7, 8, 10, 11, 13, 14, 15, 16, 17, 19, Figure 39 20,21,22,23,24,25,26,28,29,30,32,33,34,35 The dollar sunfish occurs in the littoral zone 6f Lake Okeechobee (Ager 1971), in the marshes and weedy canal margins of the northern Everglades (Dineen 1974), and throughout the Big Cypress Swamp and the southern Everglades. Although Martin (1963) had established its presence there, Kushlan and Lodge (1974) were uncertain of its occurrence south of Tamiami Trail , primarily because of its similarity to other small Lepomis species. Its status has been clarified during the present study. We have found that L. ma,ginatus is one of the most abundant centrarchids in the southern Everglades marsh. The dollar sunfish occurs in nearly all aquatic habitats in southern Florida, always in association with dense submerged vegetation, and is 240 BULLETIN FLORIDA SrATE MUSEUM VOL. 31(4) L+11,1, 6 ,),arginat 1,5 051 -2.9 I./ . *1 -9 N .1 1 I 0 4 12 16 70 2. Figure 39.- Distribution of Lepomis marginatus in fresh water in southern Florida. Open symbols signify sight records. LOFrUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 241 most numerous in sawgrass marshes and marsh prairies in the southern Everglades. This sunfish is also common in cypress sloughs and alligator ponds in the Big Cypress Swamp. L. marginams is virtually absent from east coast drainage canals (Fig. 39) but does occur in small creeks in the headwaters region. The dollar sunfish is the smallest Lepomis in southern Florida and, because of its small size, requires dense vegetation for protective cover. It appears to be one of the better adapted centrarchids to marsh conditions in southern Florida as evidenced by its abundance in a wide range of habitats. Our collections clarify the southern Florida range of this species as given by Carr and Goin (1955), Briggs (1958), Kushlan and Lodge (1974), and Bauer (1980). 56. Lepomis microlophus (Gunther) - redear sunfish (I) VS 1,2,3,4*, 5,6,7,8*, 11,13,19,21,22,24, Figure 40 25, 26, 27, 28, 29, 30, 31, 32, 34, 35, 37, 38, 39 The redear sunfish is a common centrarchid in canals and rockpits, where it is a valued food and game fish. In the eastern coastal canals, numbers of this species often surpass those of L. macrochims with which it shares similar habitats. L. microlophus ranges from Lake Okeechobee (Ager 1971) southward through the Everglades Water Conservation Areas (Dineen 1974), into the Big Cypress Swamp, the southern Everglades, and eastern coastal ridge. This is the largest Lepomis in southern Florida, and it attains its greatest size in canals and rockpits. In the southern Everglades and the Big Cypress Swamp, L. microlophus occurs primarily in alligator ponds and deeper sloughs (Kushlan and Lodge 1974). As with Lepomis macrochirus, larger redear sunfish occur in deeper, less-vegetated waters, while only juveniles inhabit the shallow, weedy marshes. The redear sunfish is the least common species of Lepomis in the southern Everglades, but in the northern Everglades, Dineen (1974) found it to be the dominant centrarchid in the marshes. Apparently L. microlophus requires a more stable, deeper-water environment than is available in the southern Everglades. Habitat preferences of L. microlophus seem to vary with location in Florida. Swift et al. (1977) collected it in larger lakes and streams in northern Florida but not in small, swampy watercourses, while Kilby (1955) found it to prefer vegetated habitats along the west central Gulf Coast of Florida. In Lake Okeechobee during the winter, adult redear sunfish exhibit a habitat shift from shallow, bulrush marshes (Scigus sp.) to deeper, open waters (Ager 1971). It appears that this species can adapt to a range of habitats, and that its rarity in natural habitats in southern Florida may be due primarily to the effects of seasonal water level fluctations. 242 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) 0 N 0 0 0 0 4 8 12 16 70 74 lili in .rn Figure 40.- Distribution of Lepomis microlophus in fresh water in southern Florida. Open symbols signify sight records. 1 = Tabb et al. (1974); 2 = Tabb and Manning (1961). LOFIUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 243 Redear sunfish have been collected in tidewater areas in northern Florida (Swift et al. 1977) and in the headwaters region of our study area (Tabb and Manning 1961). We often collected L. microlophus in coastal rivers and pools in both fresh and brackish water, up to 11.00/00. 57. Lepomis punctatus (Valenciennes) - spotted sunfish (I) VS 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 14, 15, 16, 17, 19, Figure 41 20,21,22,23,24,25,26,27,28,29,30,32,33,34, 35,36,37,38,39 The spotted sunfish is probably the most ubiquitous and abundant centrarchid in southern Florida. It occurs in the littoral zone of Lake Okeechobee (Ager 1971), ranges south through the Everglades Water Conservation Areas (Dineen 1974), and is present throughout the Big Cypress Swamp, the southern Everglades, and eastern coastal ridge (Kushlan and Lodge 1974). In the southern Everglades, it is one of the most numerous centrarchids in alligator ponds and marshes. Dineen (1974) considered L puncmtus to be the least numerous sunfish in the northern Everglades. However, we frequently collected it there during our study of fish standing crop from 1979 to 1981 (unpubl. data). Its abundance and wide distribution in our study area indicate that it is better adapted to conditions in the southern Everglades than most centrarchids. This fact, plus the absence of the larger species of centrarchids from much of the southern Everglades, may account for its relative abundance there in contrast to the northern Everglades. We collected L. puncmtus in alligator ponds, cypress sloughs, and prairies in the Big Cypress Swamp, and in canals and rockpits throughout our study area. The spotted sunfish is common in pools and creeks in the headwaters, where we collected specimens in moderately brackish water at 12.50/00 salinity. Kilby (1955) reported a salinty range of 0.00/00 to 11.80/00 along the Florida Gulf coast, but Brockman (1974) found no L puncmtus in salinities exceeding 4.90/00 in a southwestern Florida coastal canal. We observed that adult L. punctatus inhabited the open waters of alligator ponds and canals in our study area, while the juveniles occurred in the dense, submerged vegetation of the marshes and canal margins. Only rarely did we collect large L puncmms in the marsh prairies. Kilby (1955) always found the spotted sunfish in association with dense aquatic vegetation in marshes of the Gulf Coast. In southern Florida, spotted sunfish have the longest nesting season of any Lepomis species, lasting from March to November. Juvenile L punctams can be found in the Everglades marsh throughout the year. Male L. punctatus are usually larger and more vividly marked than females, and they exhibit black 244 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) irpomis *watatus 0 »Ov-x L AJE .:T . N 1 dp .0 0 1 0 0417 1. 70 '4 Figure 41.-- Distribution of Lepomis punctatus in fresh water in southern Florida. Open symbols signify sight records. LOFIUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 245 pelvic fins when reproductively active. The subspecies for peninsular Florida is L. p. punctatus. 58. Microptems salmoides Lacepede - largemouth bass (I) VS 1, 2, 4*, 5, 6, 7, 8*, 10, 11, 13, 15, 16, 21*, 22, Figure 42 23,24,25,26,27,28,29,30,31,32,35,37,38,39 This important sport and food fish is found throughout southern Florida, where it is the largest centrarchid. Bass are abundant in Lake Okeechobee and adjacent waters (Ager 1971) and are common in the canals and deep marshes of the northern Everglades (Dineen 1974). The bass ranges from the Big Cypress Swamp through the southern Everglades, to the canals of the eastern coastal ridge (Kushlan and Lodge 1974). In southern Florida, M. salmoides is most numerous and attains its largest size in the canal system. Adults inhabit the deep, open waters of canals while the juveniles find shelter around beds of submerged vegetation. In the southern Everglades and Big Cypress Swamp, bass are uncommon and occur mainly in alligator ponds, airboat trails, and deep marshes. We occasionally collected juveniles in marsh prairies, but this was very rare. In the northern Everglades, M. salmoides frequently inhabits shallow, seasonally flooded marshes (Dineen 1974), but we did not find this to be the case in the southern Everglades. M. salmoides is abundant in headwater creeks and rivers, and in the "moats" surrounding mangrove stands and bayheads in that region. The bass survives and reproduces in slightly brackish water in these coastal areas, as it does in other areas of Florida. Swift et al. (1977) collected bass in salinities ranging to 15 .60/00 in northern Florida, and Kilby ( 1955) found M. salmoides at 11.80/00 along the Florida Gulf Coast. The largemouth bass is one of the important fish predators in freshwater ecosystems in Florida. The major prey species are small fishes and crayfish. It is not well adapted to conditions in the southern Everglades, being very sensitive to the low oxygen conditions that occur in the dry season. M. salmoides is one of the first fishes to die during a natural fish kill (Kushlan 1974a), and this has limited its persistence in the southern Everglades marsh system. The Florida subspecies is M. s. floridanus (Bailey and Hubbs 1949; Philipp et al. 1983). 59. Pomoxis nigromaculatus (Lesueur) - black crappie (I) VS 37; CS 43, 160 Figure 43 The black crappie is an abundant gamefish in Lake Okeechobee. It inhabits the pelagic zone and moves into the shallows only during the spawning 246 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) Mirreptrrila wlmoidrs . 4 N 0 0 000 0 4 lili 20 . Figure 42.-- Distribution of Micropterus salmoides in fresh water in southern Florida. Open symbols signify sight records. 1 = Odum (1971). LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 247 season (Ager 1971). Its range extends southward into the northern Everglades, where small numbtrs of fish inhabit canals and rarely enter the marshes (Dineen 1974). P. nigromaculatus is very rare in extreme southern Florida. We have only three records from our study area, all taken from canals within a few kilometers of the Tamiami Canal. These represent the only known records for this species south of the Tamiami Trail. Carr and Goin (1955), Stevenson (1976), and Lee (198Od) reported that its range included the entire state of Florida, but this is incorrect. Kushlan and Lodge (1974) suggested that the crappie may have moved southward into extreme southern Florida during historic times, probably using the canal system to extend its range. Lack of suitable habitat or unfavorable water regimes probably account for its scarcity in the southern Everglades. PERCIDAE - perches 60. Etheostoma fus(fonne (Girard) - swamp darter (I) VS 1, 10, 16, 28, 31, 32, 37 Figure 43 The swamp darter is the only percid found in the Everglades. This bottom-dwelling species is common along the margins of Lake Okeechobee and adjacent canals (Ager 1971). It is fairly common along canal banks in the northern Everglades but rarely enters the marsh system (Dineen 1974). In our study area, E. fustfonne is widespread but only locally common. It appears to be absent from large areas of southern Everglades marsh, and we took it there only in a few alligator ponds. We also collected E fusiforme in a rotenone sample in a creek in the headwaters region. It is most numerous along the rocky margins of canals and rockpits in southern Florida, showing a preference for the limestone rubble substrates available in those disturbed habitats. Its range in southern Florda is more extensive than that described by Kuene and Barbour (1983) and Norden (1980). The swamp darter has been collected to the west of the Big Cypress Swamp by Carter et al. (1974), but we have only one sight record from the swamp. We think it is probably more widespread there, but because the habits and habitat of E. fusiforme make it difficult to collect without the use of rotenone or electricity, we might have missed it during routine sampling. This difficulty, in addition to its usually low numbers, is probably the reason for its absence from Big gpress Swamp samples. The subspecies is E. f. barratti, a very well-defined subspecies that had been considered a valid species in the past (Carr and Goin 1955; Collette 1962). Further study may result in re- elevation to full species status (B. B. Collette, pers. comm. to C. R. Gilbert). 248 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) Poloxis nAgrom...1.1.5 0 - Z 0 4 0 17 16 70 74 Figure 43.-- Distribution of Pomoxis nigromaculatus and Etheostoma fusiforme in fresh water in southern Florida. Open symbols signify sight records. 1 = Thomas Lodge (pers. comm.) LOFrUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 249 CARANGIDAE - jacks 61. Caranx hippos (Linnaeus) - crevalle jack (VI) VS 24*; CS 154*, 172 Figure 44 C hippos is abundant in the brackish and marine environments of northern Florida Bay and connecting waters (Tabb and Manning 1961). It occasionally enters fresh water in the coastal rivers and canals that drain the southern Everglades. Odum (1971) stated that C hippos was common in most habitats in the North River system, including small headwater creeks. We observed jacks in fresh water in Taylor River, collected a specimen in the Coral Gables Waterway, and found a dead specimen in C-103 Canal in Homestead, thereby adding additional freshwater records to those of Ross (198Oa). C hippos is known to enter fresh water in other areas of southern and central Florida, including the St. Lucie River (Gunter and Hall 1963a) and the Indian River region (Gilmore 1977). Despite its common occurrence in Florida fresh waters, it was not listed as entering fresh water in the most recent A.F.S. checklist (Robins et al. 1980). 62. Oligoplites saurus (Schneider) - leatherjacket (VI) Not collected - Figure 44 One specimen of this carangid, measuring 250 mm, was taken in fresh water from North River in 1966 (Tabb et al. 1974). This is the only freshwater record of 0. saurus in our study area. Additional freshwater specimens from southern and central Florida have been taken in the St. Lucie River (Gunter and Hall 1963a) (0.250/00) and the Indian River region (Gilmore 1977). The leatherjacket is not listed from fresh water in the A.F.S. checklist (Robins et al. 1980). LUTJANIDAE - snappers 63. LuOanus griseus (Linnaeus) - gray snapper (VI) VS 24*, 27*; CS 154 Figure 44 L. gliseus is the most abundant snapper in the marine and brackish waters surrounding our study area (Tabb and Manning 1961). The only lutjanid taken 250 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) Caranx hi No, 0 Oligo)lit,5 5{Z,INS LI'Janz,3 grisnis 6 Diallir,3 blumirri * Eurino,toin.3 w·gentms X 0 Eucitio:tomus Eula 4 4 1 3 0.8 . . 70 7. lili. K.. Figure 44.- Distribution of Caranx hippos, Oligoplites saurus, Lutianus Rriseus, Diapterus plumieri, Eucinostomus argenteus, and Eucinostomus gula in fresh water in southern Florida. Open symbols signify sight records. 1 = Odum (1971); 2 = Tabb and Manning (1961); 3 = Tabb et al. (1974); 4 = Kushlan and Lodge (1974). LOFFUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 251 in fresh water during our sampling, L. griseus commonly enters fresh water in coastal rivers and canals. Most gray snappers found in these coastal areas are juveniles (Tabb and Manning 1961) that enter the rivers and canals in winter and congregate in deep holes. L. gnkeus is much easier to see than to capture in the clear coastal waters. Specimens in fresh water from our study area were taken by Tabb and Manning (1961) in rivers north of Whitewater Bay, and by Odum ( 1971) and Tabb et al . ( 1974) in North River. L. griseus probably occurs in most river systems in southern Florida, and in large drainage canals along the east coast where salinity structures do not preclude access. These new freshwater records supplement those given by Ross (1980c). GERREIDAE - mojarras 64. Diapterus plumieri (Cuvier) - striped mojarra (VI) VS 16, 22*, 26*, 27, 34; CS 154 Figure 44 This is the common freshwater mojarra in our study area. It occurs in most coastal rivers and some canals, often many kilometers from salt water. D. plumied is often numerous in freshwater habitats, and we collected it in nearly every river system sampled. Tabb and Manning (1961) and Odum (1971) also found large numbers of D. plumien' in fresh water in the Everglades estuary. Another study in Everglades National Park (Waldinger 1968) concluded that this species favors a brackish to freshwater environment. In all habitats, striped mojarras occur at or near the bottom. Small groups of fish can be seen to constantly probe in the substrate for food items. This mojarra is normally much easier to observe than to capture in rivers and canals. All of our specimens from fresh water were either large juveniles or adults. The adults apparently spawn in fresh water and the young pass through their early life stages at sea (C. R. Robins, pers. comm.). These collections add additional freshwater records to those of Ross (198Ob). 65. Eucinostomus argenteus Baird - spotfin mojarra (VI) Not collected Figure 44 The spotfin mojarra is the most abundant mojarra in high salinity waters in southern Florida (Tabb and Manning 1961) but was frequently collected in fresh water in the North River by Odum (1971) and Tabb et al (1974). Though Tabb and Manning (1961) and Waldinger (1968) considered E argenteus to be an inhabitant of high salinity waters, others have collected it primarily in brackish, estuarine waters (Kilby 1955; Springer and Woodburn 1960). E - 252 BULLErIN FLORIDA SrATE MUSEUM VOL. 31(4) argenteus had previously been taken from fresh water in the St. Lucie (Gunter and Hall 1963b) (0.160/00) and Caloosahatchee rivers (Gunter and Hall 1965), and from the Indian River region (Gilmore 1977). We collected no specimens of E. agenteus in our sampling and must assume that both this species and Eucinostomus gula only occur sporadically in fresh water in . our study area. 66. Eucinostomus gula (Quoy and Gaimard) - silver jenny (VI) Not collected Figure 44 The silver jenny is a common inhabitant of brackish and saltwater habitats in southern Florida (Tabb and Manning 1961) but is uncommon in fresh water. E gula has been collected in fresh water from the Caloosahatchee River (Gunter and Hall 1965) (0.090/00), the Indian River area (Gilmore 1977), and from our study area in the Rookery Branch section of Shark River (Kushlan and Lodge 1974) and in North River (Odum 1971; Tabb et at. 1974). We did not collect E gula in fresh water during this study. Several studies have shown that E. gula varies in relative abundance with E. argenteus based upon habitat type and salinity. Both Kilby (1955) and Springer and Woodburn (1960) found that E gula was more abundant than E. a,genteus at high salinities along the Florida Gulf Coast. Conversely, Tabb and Manning (1961) found E gula to be less numerous than E algenteus in high salinity waters in southern Florida. In brackish water, Odum (1971) collected E. gula in similar numbers and from the same habitats as E argenteus in North River. The reasons for these differences in relative abundance are unclear. SPARIDAE - porgies 67. Archosargusprobatocephalus (Walbaum) - sheepshead (VI) VS 15, 22 Figure 45 The occurrence of this large porgy in coastal fresh waters in Florida is well documented (Herald and Strickland 1949; Gunter and Hall 1963a [0.260/001; Tagatz 1968; Burgess 1980a). Odum (1971) collected sheepshead in fresh water in North River, where it was the second most abundant gamefish. We obtained large specimens of sheepshead in rotenone samples in feeder streams along Broad River and in gill nets at Rookery Branch. A. probatocephalus probably occurs in most coastal rivers in southern Florida. We did not collect this species in the freshwater areas of coastal canals because access to most is precluded by salinity dams. It prebably inhabits those few canals without such barriers. LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 253 A.rhosargls P.*'IrphalIso Lagodon rhomboidn Bairdi,lia chry,oura a Sria...ps ..."atus - I ' . - Z 2 0 4 17 16 70 24 .ele in Km Figure 45.- Distribution of Archosargus probatocephalus, Lagodon rhomboides, Bairdiella chrysoura, and Sciaenops oceIIatus in fresh water in southern Florida. 1 - Odum (1971); 2 = Tabb et al. (1974); 3 - Hogg (1974) 254 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) 68. Lagodon rhomboides (Linnaeus) - pinfish (VI) Not collected Figure 45 L. rhomboides is exceedingly numerous on the grass flats of Florida Bay (Tabb and Manning 1961) and Biscayne Bay. The single freshwater record of pinfish in our study area was taken by Hogg (1976a) in Snapper Creek Canal. The pinfish has also been taken in southern Florida in fresh water in the St. Lucie (Gunter and Hall 1963a) (0.150/00) and Caloosahatchee rivers (Gunter and Hall 1965), and also from the Indian River area (Gilmore 1977). Elsewhere in Florida, Tagatz (1968) collected it in fresh water in the St. John's River. We did not collect L. rhomboides, but it is likely that it occasionally enters fresh water in coastal streams and canals in our study area. SCIAENIDAE - drums 69. Bairdiella chusoura (Lacepede) - Silver perch (VI) Not collected Figure 45 The single record of B. ch/ysoura from fresh water in our study area is a 110 mm fish taken in a creek between North and Roberts rivers in 1966 (Tabb et al. 1974). Other freshwater specimens from outside of our study area have been taken in the St. Lucie River (Gunter and Hall 1963a) (0.170/00), the Indian River region (Gilmore 1977), in the St. John's River (Tagatz 1968), and Charlotte Harbor (Wang and Raney 1971 ). We did not collect B. chrysoura during our sampling. 70. Sciaenops ocellatus (Linnaeus) - red drum (VI) VS 15*; CS 140 Figure 45 We collected two specimens of red drum by angling at night in the Rookery Branch of the Shark River. We also observed this species in fresh water in Broad River. Juvenile S. ocellatus use the brackish-water areas in the mangrove zone of the Everglades estuary as a nursery (Odum 1971). Both the young and adults commonly ascend Everglades coastal rivers into fresh water. Specimens ranging from 230 mm to 430 mm were taken in fresh water near Robert's River in 1966 (Tabb et al. 1974). The red drum is likely to occur in most rivers along the coast of southern Florida. Other freshwater records for the red drum in Florida are from Cedar Key (Kilby 1955) and the Caloosahatchee River (Gunter and Hall 1965). LOFrUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 255 CICHLIDAE - cichlidsi 71. Astronotus ocellams (Agassiz) - Oscar (II) - Exotic VS 1, 37*; CS 112*, 149*, 152, 158* Figure 46 This large predatory cichlid, a popular aquarium fish, was originally imported from South America by the aquarium trade. It is now established over a large area of eastern Dade County, following its escape from at least two points of origin (Hogg 1976b). It has been aided in its dispersal by anglers who have transported the fish to new locations (Courtenay et al. 1974). The oscar is only locally common within its southern Florida range, occurring primarily in canals and rockpits in Dade, Broward, and Palm Beach counties. Hogg (1976a) found that A. oceUatus inhabited deeper areas of Dade County canals than did other cichlid species, and that its population densities were low. The present range ofA. ocellatus in our study area appears to extend to Black Creek on the south and to Krome Avenue (U.S. Highway 27) on the west, although there is evidence of establishment in canals in the eastern Big Cypress Swamp. The southern Florida range is expanding as evidenced by our collection of an adult from the Tamiami Canal at its junction with L-67 Canal, and by occasional sightings of specimens in other Dade County waters, such as at the Anhinga Trail in Everglades National Park. 72. Cichlasoma bimaculamm (Linnaeus) - black acara (II) - Exotic VS 3, 4, 7*, 10, 12, 17, 18, 26, 29, 37, 38, 39 Figure 46 Of South American origin, C bimaculatum has been established in southern Florida longer than other cichlid species and presently has the widest distribution of any cichlid in extreme southern Florida. It ranges from the canals and sloughs of the Big Cypress Swamp (Kushlan 1972), eastward through the canals of the Everglades Water Conservation Areas (Dineen 1974) and southern Everglades, into canals and rockpits along the eastern coastal ridge. The first specimens of this fish in Florida were identified as Aequidens portalegrensis (Hensel) by Rivas (1965) and followed by Bailey et al . ( 1970) and Kushlan (1972). These two fishes are differentiated by their anal spine count, 1 While this paper was in press, the first U.S. collections of Cichlasoma urophthalmus were made in the Taylor Slough drainage of Everglades National Park. Several juveniles were taken in 1983 at 00/00, followed by the May 1984 collections of nesting adults near Joe Bay at 260/00. Establishment appears certain. 256 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) Astrmotus offilatus 0 Cichi«soma bimaculatum a Cichlasoma ritrinellum 4 Cichlasoma merki * Cithlasoma octoJasciatum X 0 N 0 0 0 4 8 12 16 20 74 Figure 46.-- Distribution of Astronotus ocellatus, Cichlasoma bimaculatum, Cichlasoma citrinellum, Cichlasoma meeki, and Cichlasoma octofasciatum in fresh water in southern Florida. Open symbols signify sight records. 1 = Hogg (1974); 2 = Mark Hudy (pers. comm.); 3 = Hogg (1974). LOPTUS& KUSHLAN: SO. FLORIDA FRESHWATER FISHES 257 and a recent study indicates that they may be conspecific and only subspecifically distinct (Kullander 1983). Hogg (1976a) and Courtenay and Hensley (1979a) stated that C bimaculamm was abundant in northern Dade County, but that it was unable to colonize southeastern Dade County canals, possibly because of unfavorable water conditions. However, we have collected the black acara from several canals in the Homestead area, which represents a range extension of 10 km to 16 km. Water conditions do not seem to be limiting because the black acara is quite common in several southeastern Dade County locales. Throughout its southern Florida range, C bimaculamm is much more common in disturbed habitats, especially canals, than in natural habitats. We collected the largest numbers of this species in the Big Cypress Swamp portion of the Tamiami Canal and in ditches along the eastern coastal ridge. In Everglades National Park, we found the black acara in road culverts along the main road as far south as Sweet Bay Pond. It is well established in the park only in the rocky gladelands between Taylor and Shark Sloughs. We collected or observed specimens from natural habitats in Shark Slough on just three occasions, each record consisting of only a few individuals. The black acara would seem to be well equipped to survive in the fresh waters of southern Florida. It is a prolific and frequent spawner, an omnivorous feeder (Hogg 1976a), and more resistant to drought conditions than most native species. Breeding occurs mainly from spring to fall, although we have collected fry in early January, at a time when most native centrarchids are not spawning. In typically steep-banked canals, the aggressive acara appears to compete directly with centrarchids for limited nesting space. Though it does provide some food and sport, the black acara is not as highly regarded by anglers as the native centrarchids. C bimaculatum is securely established in southern Florida and has become a locally dominant member of some canal faunas within a relatively short time. However, during the present study, we have seen an apparent displacement of this fish by Tilapia manae in canals in which C bimaculatum was once the most abundant exotic. C bimaculamm is much less numerous in eastern Dade County than it was several years ago (this study; Courtenay and Hensley 1979a). When it is sympatric with T. mariae, it is usually much less abundant and inhabits shallower, marginal areas of canals than when it is the only cichlid present. 73. Cichlasoma citrinellum (Gunther) - midas cichlid (II) - Exotic VS 39 Figure 46 While electrofishing in Black Creek Canal (C-1) in August 1980, we collected an adult male midas cichlid measuring 142 mm SL. The identification of this specimen was confirmed by C. R. Gilbert (pers. comm.). This was one of 258 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) the first records of this fish in United States waters. It was collected along the shallow, rocky margin of the canal with Tilapia manae, Cichlasoma bimaculamm, and several species of centrarchids. This specimen has been deposited at the Florida State Museum (UF 31651). Anderson et al. (1984) took numerous specimens on nests in Black Creek, which confirms its establishment. The midas cichlid is sold in local pet stores, so it seems likely that this introduction resulted from aquarium or fish farm releases. C citrinellum is native to the .Atlantic slope of Nicaragua, including the Great Lakes of Nicaragua (Miller 1966). 74. Cichlasoma meeki (Brind) - firemouth (II) - Exotic Not collected Figure 46 This attractive aquarium fish, which is native to the Yucatan peninsula (Hubbs 1936), apparently escaped from Miami area fish farms into the canal system. It was first recorded from southern Florida waters by Courtenay et al. (1974) in Dade and Palm Beach counties. It was reported to be established in small canals just south of the Tamiami Canal in Miami where its numbers and range increased rapidly (Hogg 1976a). We did not collect C meeki in the vicinity of Tamiami Canal, although we did find several other cichlid species there. If the firemouth occurs within our study area, it is either very localized or its numbers and range have decreased since Hogg's (1976b) study. 75. Cichlasoma octofasciamm (Regan) - Jack Dempsey (II) - Exotic Not collected Figure 46 Another aquarium species native to Yucatan (Hubbs 1936), C octofasciatum was reported to be established in Snapper Creek Canal (C-2) into which it escaped from tropical fish farms (Hogg 1976a). The Jack Dempsey does not appear to have extended its range in recent years, and it seems that the population was never large. Courtenay and Hensley (1979a) remarked that it was not abundant in Snapper Creek Canal. We did not collect C. octofasciatum during our sampling, and if it is still present within our study area, its range and numbers must be quite small. P. L. Shafland (pers. comm.) has never collected this species in our study area. 16. Hemichromis bimaculatus Gill - jewelfish (II) - Exotic CS 153, 154 Figure 47 The jewelfish is an aquarium escapee, native to West Africa, that was established in the Miami area prior to 1965 (Rivas 1965). The specific identity LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 259 of the aquarium escapee is now unclear following a revision of the genus by Loiselle (1979), but we have retained the nomenclature of Robins et al. (1980). Hogg (1976a) reported that H. bimaculams was common north of the Tamiami Trail in Miami and seemed to be expanding its range. In 1980, we collected this species in both the Tamiami Canal and Coral Gables Waterway where it was abundant. A small species at maturity, H. bimaculams always inhabits the shallow, littoral areas of these canals. Both adults and juveniles occur in marginal vegetation and in cavities along the canal banks. At the time of sampling (October 1980), we observed pairs ofjewelfish nesting very close to the spawning beds of Tilapia mariae and Cichlasoma bimaculatum. The aggressively defensive nature of this cichlid may explain its successful nesting in the company of larger cichlids as well as its recent range expansion to the south. 17. Tilapia aurea (Steindachner) - blue tilapia (II) - Exotic CS 8Ob, 81*, 82*, 112 Figure 47 T. aurea was originally introduced into central Florida lakes by the Florida Game and Fresh Water Fish Commission as a biological control for aquatic weeds (Courtenay and Robins 1973). The stock for United States introductions apparently originated in Israel (Courtenay and Hensley 1979a). In two decades, it has become the most numerous and wide-ranging cichlid in the state. During a recent survey of exotic fishes, specimens of T. aurea were collected in parts of Dade County but it was not widespread there OHarris 1978). We have identified and observed adult T. aurea since 1978 at the Anhinga Trail in Everglades National Park, L-31W Canal on the eastern border of the park, and in a rockpit at the Homestead airport. In 1982-83, the species spread throughout Taylor Slough where it is now breeding. The blue tilapia population in extreme southern Florida could have immigrated there through the canal system from other areas but, based upon its limited distribution, it is more likely that this population is the result of localized introductions. The Taylor Slough population probably originated from a fish-farming operation next to the park. Trewavas (1984) placed this species in the genus Oreochromis. 78. Tilapia mariae (Boulenger) - spotted tilapia (II) - Exotic VS 1*, 37, 39 Figure 47 This cichlid is presently one of the most numerous and rapidly dispersing exotic fishes in extreme southern Florida. A native of west Africa (Whitehead 1962), T. man'ae appears to have had two points of introduction into Dade County waters (Hogg 1974). The present range of T. manae now encompasses all of eastern Dade County west to Krome Avenue (State Highway 27). In 260 BULLETIN FLORIDA MATE MUSEUM VOL. 31(4) Hemichromis bimaculatus 0 Tilapia ami a lita~ia maTiaf A I lilapia moinmbicn * 1 -7 N b 00 0 4 5 12 16 70 74 Figure 47.-- Distribution of Hemichromis bimaculatus, Tilaoia aurea, Tilapia mariae, and Tilapia mossambica in fresh water in southern Florida. Open symbols signify sight records. 1 = Hogg (1974); 2 = Courtenay and Hensley (1979); 3 = Mark Hudy (pers. comm.). LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 261 1979, we observed a nesting pair even farther west at the junction of the Tamiami and L-67 Canals. Courtenay and Hensley (1979b) reported specimens from a Collier County pond, and in early 1983, we observed large numbers of spotted tilapia, including nesting adults, in Turner River Canal, Collier County. We have collected T. mariae just north of our study area in L-30 Canal and farther north (Kushlan, in prep.), but we have not yet found it in the nearby East Everglades region. Like tlfb black acara, T. manae is another species of cichlid that has been able to colonize canals in the Homestead area. These distribution data represent a 10-16 km extension south of the range given by Hogg (1976a). T. matiae is often extremely abundant wherever it occurs. Hundreds of black-barred juveniles, which had originally been described as Tilapia meeki (Whitehead 1962), are usually visible in shallow water along the canal banks, while the spotted adults inhabit the deeper mid-portions. The breeding season begins in spring in our study area and extends into the fall (unpubl. data). Both parents aggressively defend the nest and free-swimming fry against intruders. We have collected T. manae in brackish water but are uncertain of its upper salinity limit. The successful colonization of southern Florida waters by T mariae, its fecundity, and rapid dispersal suggest that it will be the next exotic fish to invade Everglades National Park. We know very little about its potential impact on the Everglades ecosystem or its ability to survive in the marshes. Further study is needed to determine its probable effects upon Everglades ecology. 79. Tilapia mossambica (Peters) - Mozambique tilapia (II) - Exotic VS 39 figure 47 T. mossambica has been introduced into many tropical countries as a food fish for pond culture. In a number of countries, it has escaped into natural waters where it has rapidly become a major component of the freshwater biota (Bardach et al. 1972; Loftus 1975). In the United States, T. mossambica has been in the aquarium trade for decades and is of special interest to hobbyists because of its mouthbrooding behavior. Its introduction into southern Florida canals was the result of releases from aquaria and escapes from tropical fish farms. T. mossambica has been established just to the north of our study area since 1972 (Courtenay et al. 1974). Hogg (1976a) reported sighting indiviudals near Snapper Creek Canal (C-2) but was uncertain of its establishment. We collected juvenile and adult T. mossambica in Black Creek Canal (C-1) and in small canals nearby. We observed males in breeding coloration in these areas, observed courtship behavior, and have collected numerous juveniles. These 262 BULLETIN FLORIDA SrATE MUSEUM VOL. 31(4) collections represent a range extension for this species since 1974. We did not find T. mossambica south of the Black Creek area, but in view of its performance in other countries, further dispersal through southern Florida seems likely. This species was recently reassigned to the genus Oreochromis (Trewavas 1984). MUGILIDAE - mullets 80. Agonostomus monticola (Bancroft) - mountain mullet (VI) CS 15lb Figure 48 Kushlan and Lodge ( 1974) did not include A. monticola in their list of southern Florida freshwater fishes, stating that it apparently did not occur here. However, on a number of occasions from 1977 to 1980, we observed juvenile mountain mullet in a small waterway in the Parrot Jungle, a Miami tourist attraction (Loftus et al. 1984). We collected a single specimen there in January 1981 and saw several others. The specimen measured 63.0 mm SL and shared this stream with many native and exotic species. In June 1982 we collected one adult and three juveniles at the same location. Additional adults and many juveniles were present in the stream on that date (Loftus et al. 1984). These fish were not introduced into the attraction (N. DeLeon pers. comm.), and, because this small waterway is connected to Snapper Creek Canal, we believe that they entered from that canal. AlthoughA. monticola has been collected in several freshwater locales in coastal areas along the Florida Atlantic and Gulf Coasts (Gilbert 1978b; Rhode 1980), there have been just two collections other than ours from the study area (Tabb et al. 1974; Randy Metzger pers. comm.). Collections of larvae in the Gulf Stream off the Florida coast (Anderson 1957) and of juveniles in Biscayne Bay (C. R. Robins pers. comm.) show that a source of recruitment exists for southern Florida. Its rarity in southern Florida can be explained by the absence of natural high-gradient streams, its usual habitat in tropical America and the West Indies (W. F. Loftus pers. observ.). The artificial stream in Parrot Jungle probably approximates this preferred habitat better than any other natural situation in southern Florida. The increase in the number of mountain mullet, including the presence of adults, at Parrot Jungle, raises the possibility that this may be the first reproducing population within the United States. LOFFUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 263 Mugil rrplifilus . - - ' - Z 0 2 0 4 8 17 16 70 74 Figure 48.- Distribution of Azonostomus monticola, Mugil cephalus, and Sphyraena barracuda in fresh water in southern Florida. Open symbols signify sight records. 1 = Tabb et al. (1974); 2 = Tabb and Manning (1961); 3 = Randy Metzger (pers. comm.). 264 BULLETIN FLORIDA SrATE MUSEUM VOL. 31(4) 81. Mugil cephalus Linnaeus - striped mullet (VI) VS 1*, 2*, 16, 22, 24*, 26*, 27, 37, 39 Figure 48 The striped mullet occurs in southern Florida fresh waters from Lake Okeechobee (Ager 1971) and the St. Lucie (Gunter and Hall 1963a) and Caloosahatchee rivers (Gunter and Hall 1965), southward into the canals and rivers of the Big Cypress Swamp and southern Everglades (Kushlan and Lodge 1974). This mullet ascends Everglades river systems into the smallest headwaters creeks, sometimes penetrating 15-25 km inland. Although these creeks are fed by the sawgrass marshes, the striped mullet never enters the marshes. It is restricted to the deeper, open waters of the creeks. We observed or collected striped mullet in every river system sampled. Most of our specimens were taken by electrofishing, and all specimens collected were adults. Tabb and Manning (1961) and Odum (1971) have previously collected it in fresh water in the Everglades estuary. The striped mullet occurs in small to moderately sized schools in freshwater habitats, and their presence at several collection sites was revealed by their characteristic leaping. Most freshwater canals with connections to salt water in southern Florida have striped mullet populations. The mullet use the canal system to move far inland into the Everglades and Big Cypress regions, but they are restricted to canal habitats there. SPHYRAENIDAE - barracudas 82. Sphyraena barracuda (Walbaum) - great barracuda (VI) Not collected Figure 48 Several specimens, ranging from 280 mm to 320 mm in length, were taken from fresh water in North River in 1966 (Tabb et al. 1974). This is the only known collection record for S. banacuda from fresh water in our study area. We have frequently seen juvenile barracuda in low salinity waters in coastal canals, but we did not collect specimens in fresh water during our sampling. C. R. Robins (pers. comm.) informed us that he has seen S. ban'acuda in fresh water at the University of Miami Campus in Coral Gables. ELEOTRIDAE - sleepers 83. Dormitator maculatus (Bloch) - fat sleeper (III) CS 15lb* Figure 49 This brackish-water species has been taken in fresh water in the Everglades estuary by Tabb and Manning (1961) and Tabb et al. (1967). It has LOFrUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 265 also been taken in Snapper Creek Canal (Hogg 1976a) and in other Dade County coastal canals (Belshe 1961). Along the Gulf Coast, Dawson (1969) stated that D. maculatus is most abundant in brackish-water habitats, but that it does enter coastal fresh water. The fat sleeper does not seem to be numerous in extreme southern Florida fresh waters. We did not collect specimens within our study area, but we did observe several large individuals in an artificial stream at Parrot Jungle. We also took two specimens in a freshwater canal in north Miami, several km north of the study area (Kushlan, in prep.). 84. Eleotds pisonis (Gmelin) - spinycheek sleeper (III) Not collected Figure 49 E. pisonis is a euryhaline species that ranges along the southern coast of Florida in estuarine habitats. It is known to enter fresh water along the east coast in the Indian River area (Gilmore 1977) and in Palm Beach County (Kushlan and Lodge 1974). The spinycheek sleeper had been collected in coastal ditches in our study area by Belshe (1961), but the salinity was not reported. The only confirmed freshwater record for extreme southern Florida was taken by Darcy (1978) in the Coral Gables Waterway. We did not collect it in our sampling. 85. Gobiomoms dormitor Lacepede - bigmouth sleeper (III) VS 37; CS 149 Figure 49 G. donnitor is another brackish-water species that enters fresh water in Florida (Lindquist 1980). The bigmouth sleeper is a large predator that normally lies motionless on the bottom while waiting for prey. We collected two large specimens in a freshwater canal near Miami, and took a third adult in Snapper Creek Canal. We also observed a small, juvenile G. donnitor in the Parrot Jungle stream. C. R. Robins (pers. comm.) informed us of a number of sightings in the Miami area and Everglades canals. This species may be more common in freshwater canals in extreme southern Florida than our collections indicate. G. donnitor has frequently been collected elsewhere in fresh water in southern and east central Florida (Kushlan and Lodge 1974; Gilmore 1977). 266 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) Chaw,odrs saburrae I Dor.Ii/Imr lillitatIs . Ele.tris Disonis A Gobiomon,5 dormiter A C,obion,1/us smaragdus * (,0},iosoma bos(i X (,obiosoma Austum 4 1.optiog,ibul 'ypr#.ides + Mic ropol,im gulo,w* N 44 5/ J 0 .. ..1. In K. Figure 49.-- Distribution of Chasmodes saburrae, Dormitator maculatus, Eleotris pisonis, Gobiomorus dormitor, Gobionellus smaragdus, Gobiosoma bosci, Gobiosoma robustum, Lophozobius cyprinoides, and Microgobius gulosus in fresh water in southern Florida. 1 = Odum (1971); 2 = Tabb and Manning (1961); 3 = Hogg (1974); 4 = Tabb et al. (1974); 5 = Darcy (1978). LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 267 GOBIIDAE - gobies 86. Gobionellus smaragdus (Valenciennes) - emerald goby (VI) Not collected Figure 49 The only freshwater specimens of this goby in southern Florida were collected by Tabb and Manning (1961) in the mangrove region of Everglades National Park. They collected it in a sample with Noturus gyrinus and Micropterus salmoides. Tabb and Manning ( 1961) also collected the emerald goby in brackish estuarine waters and in Florida Bay, and they considered it to be euryhaline. We know of no other freshwater records for G. smamgdus, and we did not collect it during our sampling. 87. Gobiosoma bosci (Lacepede) - naked goby (VI) VS 15, 24, 34 Figure 49 The naked goby inhabits low salinity waters, usually less than 220/00 (Dawson 1969), and enters fresh waters along both the Atlantic and Gulf Coasts. In southern Florida, G. bosci has been collected in fresh water in the Caloosahatchee River (Gunter and Hall 1965) and in Lake Okeechobee (Ogilvie 1969). We collected G. bosci in fresh water in the headwaters region of several coastal rivers. It was locally common in the shallows over muddy or rocky substrates. Neither Tabb and Manning (1961) nor Odum (1971) collected G. bosci in the Everglades estuary. Instead, Odum (1971) collected Gobiosoma robustum in the same locales and habitats in which we took G. bosci. 88. Gobiosoma robustum Ginsburg - code goby (VI) Not collected Figure 49 G. robustum is usually found only in moderate to high salinity waters from 220/00 to 320/00 (Dawson 1969; Springer and Woodburn 1960), although it has been collected at 2.10/00 (Wang and Raney 1971)'. We include it here on the basis of freshwater collections made by Odum (1971) in the North River, where he found it to be the most common goby. Tabb and Manning (1961) did not take G. robustum in fresh water, although they considered it to be the most abundant goby in the saline waters of the Everglades estuary. We did not collect this goby in fresh water. We have not checked Odum's (1971) specimens, but we feel that there may have been a misidentification of this species. a bosci is the common Gobiosoma in fresh water in extreme southern Florida. 268 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) 89. Lophogobius cypiinoides (Pallas) - crested goby (VI) VS 24, 34: CS 166 Figure 49 The crested goby is common in inshore, brackish habitats in southern Florida and enters fresh water in rivers and cana15 near the coast. Tabb and Manning (1961) collected it in freshwater rivers emptying into Whitewater Bay, and they considered it to be a euryhaline species. It was the second most abundant goby in the North River and maintained the highest biomass of any goby (Odum 1971). On the east coast, Hogg (1976a) collected L. cyptinoides in Snapper Creek Canal in fresh water. We collected the crested goby in several headwater rivers and coastal canals, usually in quiet water over leaf-littered bottoms. It is typically a sedentary species with dull coloration that blends well with the bottom. The gobies occupy small burrows in the bottom, often with only a part of the body exposed. The larger males actively defend territories and move about more than do smaller individuals. L. cyprinoides is locally common in coastal fresh waters and seems likely to occur in many rivers and canals with connections to salt water. Aspects of its biology and ecology in southern Florida were studied by Darcy (1978). 90. Microgobius gulosus (Girard) - clown goby (VI) VS 24; CS 146 Figure 49 M gulosus is another euryhaline species that enters fresh water in the Everglades estuary. Along the Gulf Coast, it occurs in muddy estuarine habitats as well as in areas protected by aquatic vegetation (Dawson 1969). Similarly, it inhabits areas of aquatic vegetation in the littoral zone of Lake Okeechobee (Ager 1971). Tabb and Manning (1961) found it to be the second most abundant goby in brackish water in southern Florida. They also collected it in fresh water in pools and canals and over a wide variety of bottom types in mangrove swamps. M. gulosus has also been taken in fresh water in North River (Odum 1971; Tabb et al. 1974). We found the clown goby to be common in coastal freshwater rivers and pools, especially over muddy bottoms. These data indicate that M. gulosus is probably present in fresh water throughout the Everglades estuary. We did not collect this species in coastal canals. LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 269 SOLEIDAE - soles 91. Achims lineatus (Linnaeus) - lined sole (m) Not collected Figure 50 The most abundant flatfish in Florida Bay and surrounding coastal waters (Tabb and Manning 1961), A. lineams has been collected in fresh water on several occasions in the Everglades estuary. During 1966-1972, several specimens were collected in a headwater stream at Rookery Branch (Kushlan and Lodge 1974). Tabb and Manning (1961) found the lined sole in fresh water in mangrove swamps near Whitewater Bay, and it was also collected in fresh water in North River (Odum 1971; Tabb et al. 1974). Juveniles occur more frequently in fresh water than do the adults which move into Florida Bay (Tabb and Manning 1961). Though it occurs in fresh water in the headwaters region of Everglades National Park, as well as in the St. Lucie (Gunter and Hall 1963a) (0.18 0/00) and Caloosahatchee rivers (Gunter and Hall 1965) (0.14 0/00), A. lineams is never as common in southern Florida fresh water as the hogchoker, Trinectes maculams. We did not collect it during our sampling. 92. Trinectes maculatus (Bloch and Schneider) - hogchoker (III) VS 15, 34* Figure 50 We collected the hogchoker in fresh water throughout the Everglades estuary where it was locally common. It normally inhabits slowly flowing streams and pools over muddy, leaf-littered bottoms, with which its coloration blends well. In fresh water, T. maculatus is restricted to the streams and canals of the headwaters region and does not enter the marsh habitat. It is known from fresh water from Lake Okeechobee (Ager 1971) and the Caloosahatchee River (Gunter and Hall 1965) and was previously collected in southern Florida fresh water by Tabb and Manning (1961), Odum (1971), and Tabb et al. (1974). Many specimens were collected in the headwater streams of Rookery Branch from 1965 to 1972 (Kushlan 198Oa), and we have since taken many additional specimens from that area. None of these fish exceeded 80 mm SL, supporting the findings of Springer and Woodburn (1961) and Gunter and Hall (1963a) that larger specimens inhabit more saline waters. Dovel et al. (1969) have provided definitive treatment of the salinity-size relationship of this species. 270 BULLErIN FLORIDA STATE MUSEUM VOL. 31(4) Achiru, tine..tus e '1'Tin.tes mmultitus a 0 4 8 . 16 70 74 Figure 50.- Distribution of Achirus lineatus and Trinectes maculatus in fresh water in southern Florida. 1 = Odum (1971); 2 - Tabb and Manning (1961); 3 = Tabb et al. (1974); 4 = Kushlan and Lodge (1974). LOFrUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 271 SPECIES OF DOUBTFUL OCCURRENCE OR PERSISTENCE LEPISOSTEIDAE - gars 1. Lepisosteus osseus (Linnaeus) - longnose gar (II) Carr and Goin (1955), Briggs (1958), and Stevenson (1976) gave the range of L. osseus as the entire state of Florida. We did not collect or observe this fish during our sampling, nor had the species been collected from extreme southern Florida previously. The southernmost record for L. osseus was reported by Dineen (1974) from Everglades Conservation Area 2A where it was very rare. The longnose gar does not occur in extreme southern Florida. CLUPEIDAE - herrings 2. Brevoortia smithi Hildebrand - yellowfin menhaden (VI) Kushlan and Lodge (1974) reported the freshwater occurrence of B. smithi in Everglades National Park, but its freshwater occurrence in our study area is doubtful (C. R. Robins pers. comm.). Freshwater specimens have never been reported in the literature for extreme southern Florida (Tabb and Manning 1961; Odum 1971; Tabb et al. 1974). The only freshwater record from Florida of which we are aware comes from the Indian River region (R.G. Gilmore pers. comm.). Gunter (1956) included B. smithi on a list of euryhaline species based on Carr and Goin's (1955) report, but the source for their record is not clear. B. smithi does not appear to have been collected in fresh water throughout the remainder of its range (Dahlberg 1970; Lee et al. 1980; Robins et al. 1980). 3. Brevoortia tyrannus (Latrobe) - Atlantic menhaden (VI) This menhaden was reported from southern Florida fresh water by Kushlan and Lodge ( 1974). Dahlberg's ( 1970) work on the genus Brevoortia has shown that B. tyrannus does not extend into southern Florida but is replaced by B. patronus, the Gulf menhaden. In addition, a hybrid of B. smithi and B. patronus occurs in marine areas of southern Florida (Dahlberg 1970). B. paiyonus has been collected in fresh water along the Gulf Coast (Gunter 1956), but we have found no freshwater collection records for southern Florida (Tabb and Manning 1961; Odum 1971; Tabb et al. 1974). 272 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) CHARACIDAE - characins 4. Colossoma spp. - pacus The South American pacus are among the largest characids in the world. On several occasions, large specimens have been caught by fishermen in Miami area canals (P. L. Shafland pers. comm.). C. R. Robins (pers. comm.) recently informed us of a pacu specimen (either C bmchypomum or C oculus) taken by a fisherman in a Coral Gables canal. This fisherman reported catching additional pacus from the same locale in the past. The reproductive status and ultimate persistence of pacus in southern Florida waters is presently unknown. The occasional specimen taken might merely be the result of a release by an aquarist into the canal system. CYPRINIDAE - carps and minnows 5. Notropis cha6'baeus (Cope) - ironcolor shiner (I) Stevenson (1976) stated that the range of this minnow extended to the southern tip of Florida. We did not collect N. chabbaeus in our study area, nor has it been reported from this area by other workers (Dineen 1974; Kushlan and Lodge 1974). Its occurrence in extreme southern Florida is doubtful, and we believe that its southern limit is near Lake Okeechobee (Swift 1980a). 6. Notropis emiliae (Hay) - pugnose minnow (I) Stevenson (1976) and Carr and Goin (1955) gave the range of the pugnose minnow as the entire Florida peninsula. We did not collect N. emiliae during our sampling, and we know of no records for this species south of Lake Okeechobee (Gilbert 1980a; Kushlan and Lodge 1974). The Florida peninsula subspecies, N. e. peninsularis, is very well defined. In their description, Gilbert and Bailey (1972) listed its range as peninsular Florida, south to Lake Okeechobee. Based on our sampling, we do not believe that it occurs in extreme southern Florida. APHREDODERIDAE - pirate perches 1. Aphredoderus sayanus (Gilliams) - pirate perch (I) The pirate perch ranges southward in Florida to Lake Okeechobee (Lee 1980) and the northern Everglades Water Conservation Areas (Dineen 1974). It is apparently very rare in the northern Everglades (Dineen 1974). Based on LOFIUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 273 a single specimen collected near Florida City in 1930 (Kilby and Caldwell 1955), Carr and Goin (1955), and Briggs (1958) stated that the range of A. sayanus included the entire state. Kushlan and Lodge (1974) suggested that this record was in error. C. R. Gilbert (pers. comm.) informed us that the true range of A. sayanus parallels the range of Esox americanus very closely and so would not be expected in extreme southern Florida. We did not collect the pirate perch in our sampling, nor has it been collected by other workers in the study area. Based upon the lack of additional specimens from our study area, we conclude that the collection locale of the "Florida City" specimen was erroneous. CYPRINODONTIDAE - killifishes 8. Fundulus cingulatus Valenciennes - banded topminnow (II) The banded topminnow has been recorded from southern Florida on the basis of two specimens from an unspecified location in the Tamiami Canal (Brown 1956). This record had been cited in subsequent papers on Florida fishes as documentation that the range of F. cingulams extends into extreme southern Florida (Kushlan and Lodge 1974; Relyea 1975; Stevenson 1976). Foster (1967) reexamined Brown's specimens and found them to be misidentified specimens of Fundulus chgsotus. We can find no other record of F. cingulatus south of Lake Trafford in Collier County (L. R . Rivas pers. comm.), and it was not recorded south of Lake Okeechobee by Gilbert and Burgess (198Oa). It has not been collected in the northern Everglades (Dineen 1974), in the Fakahatchee Strand (Carter et al. 1973), or in the Everglades portion of the Tamiami Canal (Hunt 1953). We did not collect F. cingulatus in our study area, and we doubt that its range extends into extreme southern Florida. 9. Fundulus lineolatus (Agassiz) - lined topminnow (II) Three specimens of F. lineolatus were collected at Chekika State Park in Dade County in 1968 by Relyea (1975). The specimens were catalogued as F. nom lineolams. Dr. Relyea allowed us to examine these specimens and we agree with their identification as F. lineolatus. With the exception of this record, the southern limit of the range of this species is usually considered to be Palm Beach County (Rivas 1966; Wiley 1980a). No specimens other than those of Relyea (1975) have been collected in extreme southern Florida (Dineen 1974; Kushlan and Lodge 1974; present study). Crowder (1974) included F. notti on a list of south Florida fishes but provided no reference or collection data to support the record. Chekika State Park is a popular fishing 274 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) and recreation area, and we and L. R. Rivas (pers. comm.) believe that the specimens Relyea caught had probably been introduced into this lake. We did not collect F. lineolatus during our 1977 sampling of Lake Chekika and doubt that it has successfully established itself in our study area. 10. Leptolucania ommata (Jordan) - pygmy killifish (II) Relyea (1975) stated that Leptolucania ommam ranged throughout the Florida peninsula in fresh water. We have found no records for this species south of central Florida (Briggs 1955; Gilbert and Burgess 1980c) and doubt its occurrence in southern Florida. Relyea (pers. comm.) agrees that he misstated the range of L. ommata in his 1975 paper. BLENNIDAE - combtooth blennies 11. Chasmodes saburrae Jordan and Gilbert - Florida blenny (VI) Not collected Figure 49 C sabunae was collected by Tabb and Manning (1961) at 00/00 salinity in the Everglades estuary near Whitewater Bay. They stated that it was the common brackish-water blenny in that area, occurring on oyster bars in clean water where salinities normally ranged from 100/00 to 270/00. The Florida blenny cannot be considered a true member of the freshwater ichthyofauna, because it would be exposed to fresh water only during heavy runoff in the wet season. We did not collect this species, nor are we familiar with other freshwater records. Williams (1983) noted no freshwater records in his systematic revison of the genus. HYBRIDS In general, natural hybridization between closely related freshwater fish species is not uncommon. The process appears to be increasing because of human modification of aquatic environments and fish distribution (Lagler et al. 1977). We found little evidence of hybridization in southern Florida freshwater fishes. In our collections of thousands of fishes, we found only two hybrids, both centrarchids. Both were taken in borrow ponds in which the parental stocks were forced to nest in close proximity because suitable spawning habitat was limited. Such nest site competition is often responsible for the occurrence 6f sunfish hybridization (Lagler et al. 1977). One specimen, a relatively rare hybrid of Lepomis macrochims x Lepomis punctatus, was identified by R. M. LOFrUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 275 Bailey and has been deposited at the University of Michigan Museum of Zoology (UMMZ 209310). The second hybrid , apparently Lepomis macrochims x Lepomis microlophus, was observed but not captured. Only one other instance of hybridization, a Lepomis microlophus x Lepomis gulosus cross, has been reported from extreme southern Florida (Martin 1963). We detected no hybridization among members of the common families Poeciliidae, Cyprinodontidae, or Ictaluridae, and we conclude that hybridization is rare in southern Florida fresh water. Furthermore, centrarchid hybrids are rare in all known collections of Florida freshwater fishes (C. R. Gilbert pers. comm.). One of the few published records of hybrid sunfishes in Florida described a natural hybrid population that probably resulted from the lack of suitable nesting sites for one of the parent species (Birdsong and Yerger 1967). Table 4. Fishes documented from southern Florida fresh waters in the present study, but not listed from this region by other authors. Number(s) in parentheses refer(s) to the citations in which the range of the species does not include extreme southern Florida. 1 = Lee et al. (1980), 2 = Stevenson (1976), 3 - Carr and Goin (1955), 4 - Kushlan and Lodge (1974). Anguilla rostrata (1) Elassoma evergladei (1) Dorosoma cepedianium (1) Enneacanthus gloriosus 03 Dorosoma petenense (1) Lepomis maqinatus (1 , 3 , 4) Notropis maculatus 0) Lepomis punctatus (3) Notropispetersom ( 1, 2) Etheostoma fusifomie (5 Erimyzon sucetta 0) Caranx h(ppos ( 1 ) Ictalurus punctatus 0) Agonostomus monticola ( 1 , 4) Fundulus seminolis 0, T) Gobiomoms dormitor ( 1) Labidesthes sicculus 0) 276 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) DISCUSSION Range Revisions and New Records A number of range clarifications resulted from our study (Table 4). New distributional data have extended the ranges of the coastal shiner (Notropis petersoni), gulf killifish (Fundulus gmndis), and Seminole killifish (Fundulus seminolis) beyond those presented by Stevenson (1976). Carr and Goin (1955) did not include extreme southern Florida in the ranges of dollar sunfish (Lepomis maminatus) and spotted sunfish (Lepomis puncmms), but we have found both species to be quite common there. Our collection data also showed that the known freshwater ranges of 16 species extend into extreme southern Florida, thus revising the ranges presented by various authors in species accounts in Lee et al. (1980). The ranges of several species have been reported to extend into extreme southern Florida, but our sampling and literature review have provided no support for such reports. The chain pickerel (Esox niger) and black crappie (Pomoxis nigromaculatus) range south only to the vicinity of Tamiami Trail rather than to the tip of the peninsula (Briggs 1958; Stevenson 1976). Carr and Goin (1955), Briggs (1958), and Stevenson (1976) stated that the ranges of the longnose gar (Lepisosteus osseus), ironcolor shiner (Notropis chalybaeus), pugnose minnow (Notropis emiliae), and pirate perch (Aphrododems sayanus) extend into extreme southern Florida, when, in actuality, they do not extend south of the vicinity of Lake Okeechobee (Gilbert and Bailey 1972; Wiley 198Ob; Swift 198Oa; Lee 198Ob). Brown's (1956) record of the banded topminnow (Fundulus cingulams) from the Tamiami Canal was found to be based upon a misidentification (Foster 1967), while the reported occurrence of the pygmy killifish (Leptolucania ommata) throughout the peninsula is incorrect (Relyea 1975). We have found no records for two species of menhaden (Brevooma spp.) reported to occur in extreme southern Florida fresh water by Kushlan and Lodge (1974). From our sampling, and during our literature review of southern Florida fishes in fresh water, we found specimen records for euryhaline species that had rarely or never been taken from fresh water. Freshwater records for several species had been published but were not listed from fresh water by Robins et al. ( 1980). These included the diamond killifish (Adinia xenica) (Tabb and Manning 1961 ; Odum 1971 ; present study), goldspotted killifish (Floridichthys ca,pio) and silver jenny (Eucinostomus gula) (Odum 1971; Tabb et al. 1974; present study), the longnose killifish (rundulus similis) (Gilmore 1977; present LOFIUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 277 study), jewfish (Epinephelus itajam) (Tabb et al. 1974), crevalle jack (Caranr hippos) (Odum 1971 ; Gilmore 1977; present study), leatherjacket (Oligoplites saums) (Tabb et al. 1974), great barracuda (Sphyraena banucuda) (Tabb et al. 1974), emerald goby (Gobionellus smaragdus) (Tabb and Manning 1961), and the crested goby (Lophogobius cypn'noides) (Odum 1971; Hogg 1976a; present study). Records for other species that are infrequent in fresh water in southern Florida included rivulus (Rivulus mannoratus) (Tabb and Manning 1961), spotfin mojarra (Eucinostomus aigenteus) (Odum 1971; Tabb et al. 1974), code goby (Gobiosoma robustum) (Odum 1971), mountain mullet (/Igonostomus monticola) (Tabb et al. 1974; Loftus et al. 1984), and pinfish (Lagodon rhomboides) (Hogg 1976a). We collected the first freshwater specimens of mangrove gambusia (Gambusia rhizophome) for the United States, and we also took specimens of two species that are uncommon in Florida freshwater collections--the bull shark (Carcharhinus leucas) and gulf killifish. Many of these euryhaline species are not uncommon in southern Florida fresh water, especially in the estuaries, but specimen records are quite rare due to difficulties in collecting and problems of accessibility. We think that more intensive collecting along the southwestern coast of Florida would yield freshwater records for additional euryhaline species. Relyea (1975) discussed the paucity of specimen records for three species of euryhaline killifishes along the southwestern coast of Florida. He stated that the gulf killifish, longnose killifish, and the rainwater killifish (Lucania parva) had similarly disjunct distributions between Everglades City and Cape Sable. However, Odum (1971) found that the rainwater killifish and gulf killifish were common within this area, and our sampling data have shown that no such disjunctions in distributions exist (Figs. 27,29). Thus, these species range along the entire southwestern tip of Florida. We believe that the inaccessibility of the area and resulting lack of collecting effort have produced the mistaken impression that allopatric Gulf, Atlantic, and Florida keys populations exist for those species. Duggins (198Oa) studied the taxonomic relations of several species of silversides and killifishes using electrophoretic techniques. He interpreted his results with respect to the range disjunctions reported by Relyea (1975). Because our data show that the assumed range disjunctions do not exist, Duggins's interpretations must be re-evaluated. He suggested that a climatic warming trend has made southern Florida unsuitable for the gulf and rainwater killifishes. However, because we found both species to be locally abundant, we must doubt that interpretation. During our study, we found a substantial number of misconceptions in accepted range data for southern Florida freshwater fishes. We have provided many range extensions and corrections. Systematic surveys of areas like 278 BULLETIN FLORIDA SrATE MUSEUM VOL. 31(4) southern Florida, which form the terminus of ranges for many species, are particularly important because such areas weigh heavily in considerations of speciation, environmental limitations, and zoogeography. An incomplete understanding of species distributions can lead to erroneous assumptions and interpretations of zoogeographic patterns and taxonomic differentiation. Faunal Derivation and Salinity Relations The entry of marine fishes into fresh water, particularly in Florida, has been a matter of interest for many years (Gunter 1942; Odum 1953; Gunter and Hall 1963b; Kushlan and Lodge 1974). In addition, the classification 6f freshwater fishes according to their salinity tolerances has been of value in both zoogeographical and ecological studies. Based upon our work, we set the number of fishes known from fresh water in extreme southern Florida at 92 species (Table 5). We collected or observed 70 of these during our sampling. Records of the remaining 22 species were obtained from the literature and from personal communications. Of the 92 species, 80 (87%) are native, and 12 (13%) are introduced. The native primary freshwater fishes belong to eight families and include 20 (25.3%) species. Native secondary freshwater fishes belong to two families and include 8 (10%) species. Native peripheral fishes belong to 24 families and include 52 (65%) species (Table 5). Of the typically freshwater species, 16 seem to be restricted to fresh water, while another 10 species enter brackish areas. Several fishes of "primary" freshwater families, particularly largemouth bass and redear sunfish, breed in low-salinity, brackish waters in southern Florida. Few native fishes belong to the category of secondary freshwater fishes, but 10 of 12 exotic species in the study area are secondary freshwater fishes. All native primary and secondary freshwater species in southern Florida are derived from temperate North American fish stocks. No native species has its origin in the neotropical region. Most species are widespread throughout the southeastern United States coastal plain, and the ranges of several extend north to the Great Lakes region. Although no endemic species occur in southern Florida, several of the most abundant species are restricted to Florida and adjacent states: Jordanella floridae, Lucania goodei, Heterandria formosa, and Lepisosteusplatyrhincus (Swift et al. 1977). Most primary and secondary freshwater families in southern Florida experience a reduction in the number of genera and species from north to south on the peninsula. As a result, the southern Florida freshwater ichthyofauna is rather depauperate.in comparison to that of northern Florida and the southeastern United States. At the southern end of the peninsula, the Lake Okeechobee region is the site of a faunal break for six species that are widespread to the north but do not enter the Everglades. These species are LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 279 Lepisosteus osseus, Esox americanus, Notropis chalybaeus, Notropis emiliae, Ictalums cams, and Aphrododems sayanus. Reasons for the progressive reduction in species from north to south in Florida have been discussed by Briggs (1958) and Kushlan and Lodge (1974). The most important of these seems to be the unsuitability Of the available aquatic habitats or the climate for temperate species. Of the 52 peripheral species, four are diadromous (American ee\, Anguilla rostrata; mountain mullet, Agonostomus monticola; fat sleeper, Donnitator maculams; and bigmouth sleeper, Gobiomoms dormitor); 36 species are restricted to coastal waters, and 15 marine species are found far inland in fresh water. Peripheral species that penetrate far inland, but occur only in canals, include snook (Centropomus undecimalis), tarpon (Megalops atlanticus), American eel (Anguilla rostrata), and striped mullet (Mugil cephalus). Several peripheral species that have been able to colonize fresh water in the Everglades marsh and Big Cypress Swamp are the diamond killifish, sheepshead minnow (Cyprinodon variegatus), sailfin molly (Poecilia lat*inna), and marsh killifish (Fundulus confluentus). Outside of the Florida peninsula, these species rarely penetrate freshwater habitats and are often restricted to coastal areas (Johnson 1980; Burgess 1980g; Hardy 1980). In the Ochlockonee River of the Florida panhandle, the abovementioned cyprinodontoids, as well as the rainwater killifish, flagfish Uordanella floridae). Seminole killifish, and inland silverside (Menidia beryllina), are restricted to within 10 km of the coast (Swift et al . 1977). Two factors that may account for this restriction in the panhandle are the cooler winter temperatures and the higher gradient streams there (Swift et al. 1977). Additionally, the greater diversity of primary freshwater fishes in the panhandle (e.g. 15 species of cyprinids compared to 3 species in southern Florida) may present competitive barriers to colonization by these secondary and peripheral fishes. In southern Florida, the paucity of small primary freshwater species, due in part to high ambient water temperatures, seasonal droughts, and habitats generally Unsuitable for temperate stream fishes, probably accounts for domination of natural habitats by cyprinodontids and poeciliids. Such dominance by peripheral fishes when primary species are rare or absent was also noted by Myers (1949). The major factor influencing penetration of fresh water by euryhaline forms in southern Florida is water chemistry composition, particularly the relatively high concentrations of sodium, chloride, and calcium (Table 1). All areas of southern Florida and most of the peninsular coastal areas were submerged during the Pleistocene, when the Pamlico terrace was formed at sea levels ranging from 7.6 to 9.1 m above the present level (Alt and Brooks 1965). Sediments deposited at that time contribute to the present-day ionic composition of southern Florida fresh water (Table 1). The distribution of a number of peripheral freshwater species in Florida appears to correspond to Table 5. Fishes known to occur in fresh water in:southern Florida. An asterisk indicates a species that was not collected in this study, but that had been recorded previously from fresh water in the study area. Roman numerals following the common name denote the salinity classification of the species as either primary freshwater (I), secondary freshwater (II), or peripheral (III-VI) after Myers (1949). Exotic species are so noted. Family Species Common Name CARCHARHINIDAE 1. Carcharhinus kucas bull shark (VI) DASYATIDAE 1. Dasyatis sabina Atlantic stingray (VI) LEPISOSTEIDAE 3. Lepisosteus platyrhincus Florida gar (II) AMIIDAE 4. Amia calva bowfin (I) ELOPIDAE 5. Elops saurus lad)fish (VI) 6. Megalops atianticus tarpon (VI) ANGUILLIDAE 7. Anguilla rostrata American eel (V) CLUPEIDAE 8. Dorosoma cepedianum gizzard shad (IV) 9. Dorosoma petenense threadfin shad .(IV) ENGRAULIDAE * 10. Anchoa mitchilli bay anchovy (VI) ESOCIDAE 11 . Esox niger chain pickerel (I) CYPRINIDAE 12. Notemigonus crysoleucas golden shiner (I) 13. Notropis maculatus taillight shiner (I) 14. Notropis petersoni coastal shiner (I ) CATOSTOMIDAE 15. Enmyzon sucetta lake chubsucker (I) ICTALURIDAE 16. Ictalurus natalis yellow bulthead (I) 17 . Ictalurus nebulosus brown bullhead (I) 18. Ictalurus punctatus channel catfish (I) 19. Noturus gyrinus tadpole madtom .(1) CLARIIDAE 20. Clanas batrachus walking catfish (I) - Exotic ARIDAE 21. Anus felis hardhead catfish (VI) 22. Bagre. marinus gafftopsail catfish (VI) LORICARIIDAE * 23 . Hypostomus sp. suckermouth catfish (I) - Exotic BELON1DAE * 24. Strongylura marina Atlantic needlefish (VI) * 25. Strongylura notata redfin needlefish (VI) 26. Strongylura timucu timucu (VI) CYPRINODONTIDAE 27. Adinia xenica diamond killifish (VI) 28. Cyprinodon variegatus sheepshead minnow (IV, VI) 29. Floridichthys camio goldspotted killifish (VI) 30. Fundulus chrysotus golden topminnow (II ) 31. Fundulus confluentus marsh killifish (VI) 32. Fundulus grandis gulf killifish (VI) 33. Fundulus semindis Seminole killifish (II) 34. Fundulus similis longnose killifish (VI) 35. Jordanella flondae flagfish (II) 36. Lucania goodei bluefin killifish (II) 37 . Lucania parva rainwater killifish (II) * 38 . Rivulus marmoratus rivulus (II) POECILIIDAE 39. Belonesox belizanus pike killifish (II) - Exotic 40. Gambusia aflinis mosquitofish (II) 41. Gambusia rhizophorae mangrove gambusia (VI) 42. Heterandria formosa least. killifish (II) 43. Poecilia latipinna sailfin molly (VI ) ATHERINIDAE 44. Labidesthes sicculus brook silverside (III) 45 . Menidia beryllina inland silverside (IV) CENTROPOMIDAE * 46. Centropomus ensiferus swordspine snook (VI) * 47. Centropomus parallelus fat snook (VI) * 48. Centropomus pectinatus tarpon snook (VI) 49. Centropomus undecimalis snook (VI) Table 5 continued. Family Species Common Name CENTRARCHIDAE 51. Elassoma evergladei Everglades pygmy sunfish (I) 52. Enneacanthus gloriosus bluespotted sunfish (I) 53. Lepomis gulosus warmouth (I) 54. Lepomis macrochints bluegill (I) 55 . Lepomis marginatus dollar sunfish (I) 56. Lepomis microlophus redear sunfish (I) 51. Lepomis punctatus spotted sunfish (I) 58. Micropterus salmoides largemouth bass (I) 59. Pomoxis nigromaculatus black crappie (I) PERCIDAE 60. Etheostoma fusiforme swamp darter (I) CARANGIDAE 61. Caranx hippos crevallejack (VI) * 62. Oligoplites saurus leatherjacket (VI) LUTJANIDAE 63. Lutjanus gnseus gray snapper (VI) GERREIDAE 64. Diapterus plumien striped mojarra (VI) * 65 . Eucinostomus argenteus sp6tfin mojarra (VI) * 66. Eucinostomus gula silver jenny (VI) SPARIDAE 61. Archosargus probatocephalus sheepshead (VI) * 68 . Lagodon rhomboides pinfish (VI) SCIAENIDAE * 69 . Bairdiella chrysoura silver perch (VI) 70. Sciaenops ocellatus red drum (VI) CICHLIDAE 71 . Astronotus ocellatus oscar (II) - Exotic 72. Cichlasoma bimaculatum black acara (II) - Exotic 73 . Cichlasoma citrinellum midas cichlid (II) - Exotic * 74. Cichlasoma meeki firemouth (II) - Exotic * 75 . Cichiasoma octofasciatum Jack Dempsey (II) - Exotic 16. Hemichromis bimaculatus jewelfish (II) - Exotic 77 . Tilapia aurea blue tilapia (II) - Exotic 18. Tilapia mariae spotted tilapia (II) - Exotic 79 . Tilapia mossambica Mozambique tilapia (II) - Exotic MUGILIDAE 80. Agonostomus monticola mountain mullet (IV) 81. Mugit cephalus striped mullet (VI) SPHYRAENIDAE * 82. Sphyraena barracuda great barracuda (VI) ELEOTRIDAE * 83 . Dormitator maculatus fat sleeper (III ) * 84. Eleotris pisonis spinycheek sleeper (III ) 85. Gobiomonts dormitor bigmouth sleeper (III) GOBIIDAE * 86 . Gobionellus smaragdus emerald goby (VI) 87. Gobiosoma bosci naked goby (VI) * 88 . Gobiosoma robustum code goby (VI) 89 . Lophogobius cyprinoides crested goby (VI) 90. Microgobius gulosus clown goby (VI) SOLEIDAE * 91 . Achirus lineatus lined sole (VI) 92. Trinectes maculatus hogchoker (VI) Total number of species 92 Total number of native species 80 Total native primary species 20 Total native.secondary species 8 Total native peripheral species 52 Total number of exotic species 12 282 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) areas that were submerged below the Pamlico terrace (Odum 1953; Johnson 1974). Odum (1953) proposed that high chloride concentrations in fresh water were responsible for fostering marine invasions in Florida. Gunter (1961) disputed this hypothesis, indicating instead that freshwater penetration is made possible by the presence of calcium; an interpretation first proposed by Breder (1934). Other studies have also stressed the importance of calcium as an osmoregulatory aid for euryhaline organisms in fresh water (Pickford et al. 1966; Hulet et al. 1967; Carrier and Evans 1976). Evans (1980) presented a review of the means by which both freshwater and marine fishes regulate osmotic and ionic balances. For whatever reason, the chemical Composition of southern Florida fresh waters is conducive to invasions and occasional establishment by euryhaline fishes. Few freshwater species enter saline waters in our study area, in contrast to the large number of peripheral species that penetrate fresh water. In a study of salinity tolerance in Fundulus, Griffith (1974) found that typically freshwater species appear to have no tolerance for saline waters, whereas brackish-water inhabitants are highly tolerant of fresh water. He suggested that, although the freshwater Fundulus species evolved from euryhaline ancestors, they have lost the ability to adjust to saline habitats because of their prolonged isolation in fresh water. Odum (1953) also noted that the normal salinity fluctuations in estuaries probably act as a barrier to many freshwater species. The5e factors may account for the low incidence of freshwater fishes in brackish areas of the Everglades estuary. Habitat Occurrence and Distribution Patterns Everglades Marsh Prairies.--The marsh prairie habitat supports all 30 species of native fishes that occur in the southern Everglades (Table 6). During our study no exotic fishes were regularly collected in this habitat. Species composition of the marsh prairie is dominated by small poeciliids and cyprinodontids (36.6% of the species), juvenile centrarchids, and ictalurids. We found Florida gar (Lepisosteus plaorhincus), bowfin (Amia calva), and other large fishes in this habitat only during the wet season. Although there are 24 (80%) primary or secondary freshwater fish species in this habitat, secondary and peripheral species are numerically dominant. Near the mangrove-Everglades marsh interface, the character of some marshes changes to one of sparse vegetation on mari substrates. Such mari- bottomed marshes are characterized by an assemblage of cyprinodontids and poeciliids that differs in relative abundance from that found in marshes with peat substrates. All of the fishes in these sparsely vegetated habitats have pale colorations, presumably to better match the substrate. The killifishes are LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 283 especially adept at diving into the substrate for concealment at the slightest disturbance. Mosquitofish (Gambusia atinis), sailfin molly, diamond killifish, sheepshead minnow, marsh killifish, and flagfish are the typical inhabitants of these marshes. Most of the fishes tend to school or swim in small group5 in this habitat. The coastal marshes are very important freshwater feeding grounds for wading birds in southern Florida (Ogden et al. 1976; Frohring and Kushlan, unpubl. data). Mari-bottomed marshes are also found in the East Everglades, where they support a similar ichthyofauna. Everglades Sawgrass Marshes.--The sawgrass habitat is a difficult one fof fishes. Only 16 (53%) of the 30 native Everglades fishes were collected there (Table 6). Larger fishes are uncommon in this habitat, probably because the high density of plant stems and the shallow water inhibit movement. Dissolved oxygen levels are often low. The earlier dry-down in spring and accompanying low oxygen levels tend to force fishes from sawgrass habitats into prairies and ponds. The fish community in sawgrass strands is mainly composed of cyprinodontids and poeciliids (50% of the total) and small centrarchids. Most of the fishes are primary and secondary freshwater species. In the rocky gladelands, sawgrass stands are restricted to solution holes that are subject to frequent, rapid dry-downs. This is a particularly harsh habitat for aquatic animals, and fish diversity and numbers there are consistently low. This is one of the few natural areas of the Everglades that has been successfully colonized by the black acara (Cichlasoma bimaculamm) and walking catfish (Clarias batrachus). Everglades Alligator Ponds.--These ponds are the deepest natural habitats in the Everglades marsh, and they hold water throughout the dry season except during the most severe droughts (Table 6). In the wet season, the ponds are occupied by small numbers of yellow bullheads (Ictalums natalis), gar, and large centrarchids in the open-water areas, and schools of large mosquitofish, sailfin mollies, and golden topminnows (Fundulus chgsotus) at the surface and along the margins. Overall, we collected 21 species in ponds during the wet season, of which 43% were poeciliids and cyprinodontids. When water levels begin to fall during the dry season, large fishes concentrate in the ponds (Kushlan 19748, 1976a). We collected 12 species when ponds were drying, with Florida gar, yellow bullhead, and warmouth (Lepomis gulosus) predominating. At this time, poeciliids and cyprinodontids comprised only 26% of the species present. A total of 28 native species and two exotic species was collected in this habitat (Table 6), but the exotic species were rare. The ichthyofauna of the three majn habitats in the southern Everglades is numerically dominated by small fishes, especially killifishes and livebearers. Small centrarchids and ictalurids are also common in the marsh system. Larger species, such as gar, bowfin, and large centrarchids, invade the marshes during the wet season but occur only in alligator ponds and canals when waters recede 284 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) in the dry season. Catostomids, percids, and cyprinids are each represented by only one to three species in the Everglades marsh and are relatively uncommon. Exotic fishes have made few inroads into the Everglades marsh so far. Big Cypress Swamp.--We recorded 29 native and 3 exotic species in fresh water in the Big Cypress Swamp (Table 6). The species composition is nearly identical to that of the Everglades marsh, except that the tadpole madtom (Notums gy,inus) was not collected in the swamp. The ichthyofauna is dominated by small fishes in the cypress sloughs and marshes, and by Florida gar, ictalurids, and centrarchids in ponds. Poeciliids and cyprinodontids comprise 36% of the species in the swamp, the same percentage as in the Everglades. Much of the swamp has a shorter hydroperiod than the southern Everglades, so that its marshes dry earlier and remain dry longer. The result is that fishes are confined to ponds for extended periods. However, most of the large cypress sloughs and strands contain many ponds that can support fishes while the marshes are dry. Exotic fishes have colonized the natural areas of the Big Cypress Swamp to a greater extent than in the southern Everglades marsh. The black acara and walking catfish occur in a number of ponds and strands, and a population of spotted tilapia (Tilapia mariae) is also established. Several peripheral fishes have penetrated the Big Cypress Swamp through the canal system, so that striped mojarra (Diapterus plumieri), needlefish (Strongylura timucu), tarpon, striped mullet, and snook (Centropomus undecimalis) inhabit portions of Tamiami Canal in the Swamp. If these peripheral species are included in the total number collected, then 34 native species, and 37 species overall, occur within the Big Cypress Swamp. Kushlan and Lodge (1974) suggested that differences exist between the faunas of the Big Cypress Swamp and Everglades. Our data on the ichthyofaunas suggest that differences in species richness and species composition between the two regions are presently minimal. However, there are differences in species abundance that seem to result primarily from differences in the available habitat types. The Everglades system has no extensive habitat similar to the heavily shaded, ponded cypress strands. In these strands, small poeciliids and cyprinodontids are less numerous than in the surrounding marshes, but large dollar sunfish, spotted sunfish, and warmouth are very common. Carlson and Duever (1977) reported similar species distributions in their study of wet prairies and strands in the northern Big Cypress Swamp. Apart from these minor differences, the two major natural areas of southern Florida presently possess nearly identical fish faunas. Canal System.--We recorded 49 native species and 12 exotic species in canals in the study area (Table 6). To understand fish distribution in canals, we analyzed the eastern coastal ridge canals separately from canals in the Table 6. Distribution of fishes in fresh water in seven major habitats in southern Florida, with a relative index of abundance. C = common, UC = uncommon, - = not collected in that habitat, L = localized occurrence, and ? = status uncertain. See Table 5 for common names of fishes. LO F rU S & KU S SO . FLO R ID A FR E S H W ATE R FISH ES 285 Borrow Everglades Everglades Everglades Big Canals in ponds and Mangrove marsh sawgrass alligator Cypress Evergla(les & canats on streams & Species praines marsh ponds Swamp Big Cypress east coast ponds 1. Carcharhinus Qucas UC 2. Dasyatis sabina - - - UC 3. Lepisosteus platyrhincus UC UC C C C UC-L C 4. Amia calva UC UC UC UC C UC-L UC 5. Elops saurus - - C 6. Megalops atianticus UC UC-L C 7. Anguilla rostrata C C UC 8. Dorosoma cepedianum ? UC-L 9. Dorosoma petenense UC-L UC-L 10. Anchoa mitchilli - UC 11. Esox niger - - C-L - - 12. Notemigonus crysoleucas UC C C C-L UC UC 13. Notropis maculatus UC UC UC - - UC 14. Notropis petersoni UC UC UC UC UC UC 15. Erimyzon sucetta UC - C C C UC UC 16. Ictalurus natalia UC UC C C C UC UC 17. Ictalums nebulosus UC - UC UC UC UC - 18: Ictalurus punctatus - - - - UO UC? - 19. Noturus gyrinus UC UC C - UC UC UC 20. Clanas batrachus - UC UC C C C UC-L 11. Arius felis - - - C 22. Bagre marinus - - UC 23. Hypostomus sp. 1 1 - 24. Strongylura marina - UC! 25. Stronglura notata - UC? 26. Strongylum timucu - - - UC? UC? C 27. Adinia xenica UC UC - UC UC - C 28. Opnnodon vanegatus C - UC C C-L UC C 29. Floridichthys carpio - - - UC Table 6 Continued. 286 B U LLE T IN F LO R ID A S TATE M U S E U M V O L. 31(4) Borrow Everglades Everglades Everglades Big Canals in ponds and Mangrove marsh sawgrass alligator Cypress Everglades & canals on streams,& Species prairies marsh ponds Swamp Big Cypress east coast ponds 30. Fundulus cho,soms C C C C C UC-L C 31. fundulus confluentus C UC UC C C UC-L C 32: Fundulus grandis - - - - - UC 33. Fundulus seminolis UC - UC UC C-L - UC 34. Fundulus similis - - - - UC 31 ~ C C UC C C UC-L C 36. Lucania goodei C C C C C C UC 31. Lucaniaparva UC - - UC - C 38. Rivulus marmoratus - - - UC! 39. Belonesox belizanus - - - C-L C-L 40. Gambusia a#inis C C C C C C C 41. Gambusia rhizophome - - - - UC-L 42. Heterandna formosa C C C C C C C 43 Poeci/ia lan)inna C UC C C C C C 44. Labidesthes sicculus UC-L - UC C C C UC 45 . Menidia bery{[ina - - - - UC C 46. Centropomus ensiferus - - - UCI 47. Centropomusparallelus - - - - UC? 48. Centropomus pectinatus - - - - UO 1 49. Centropomus undecimatis - - - UC-L UC-L C 50. Epinephelus itajara - - - 9 51. Elassoma evegladei C C UC C UC - UC 52. Enneacanthus glon'osus UC - UC UC C UC-L UC 53. Lepomis gulosus C UC C C C C C 54. Lepomis macrochims UC - C C-L C C UC 55. Lepomis ma/ginatus C C C C C UC-L C 56. Lepomis microlophus UC - UC C-L C C C 57. Lepomis punctams C C C C C C C 58. Micropterus salmoides UC - UC C-L C C C 59. Pomoxis nigromaculatus - - - UC-L UC-L - 60. Etheostoma fusiforme UC UC UC C-L C-L UC 61 . Caranx hippos - - UC-L C? 62. Oligoplites saunts - - LO F rU S & KU S SO . FLO R ID A FR E S H W ATE R FISH ES 287 63. Luijanus gnseus - UC-L C 64. Diapterus plumien - C-L C-L C 65. Eucinostomus.argenteus - - 9 66. Eucinostomus guia - 9 61. Archosargus probatocephalus - - C 68. Lagodon rhomboides - UC-L ? 69. Bairdiella chrysoura - 9 10. Sciaenops ocellatus - - - UC 71 . Astronotus ocellatus - - - UOL UC - 72. Cichlasoma bimaculatum UC UC UC C C-L C-L - 73. Cichiasoma citrinellum - 74. Cichlasoma meeki - 1-L 15. Cichlasoma octofasciatum - ?-L 76. Hemichromis bimaculatus - - C-L 77. Tilapia aurea UC-L UC-L - C-L UC-L 78. Tilapia man'ae - - C-L C 19. Tilapia mossambica - - C-6 80. Agonostomus monticola - ?-L ? 81. Mugilcephalus - UC-L C-L C 82. Sphymena barracuda - ? ? ? 83. Dormitator maculatus - UO UC 84. Eleotris pisonis - - UC! - 85. Gobiomorus dormitor - UO UC 86. Gobionellus smaragdus - - UC 87. Gobiosoma bosci - C 88. Gobiosoma robustum - - UC? 89. Lophogobius cypnnoides - UC-L C 90. Microgobius gulosus - - C 91 . Achirus [ineatus - UC 92. Trinectes maculatus - C 288 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) Everglades and Big @press Swamp. Canals in the Everglades and Big Cypress Swamp generally have species compositions similar to those of the natural habitats that they dissect. They appear to function a5 long and deep alligator ponds and are inhabited by the same fishes that occur in natural ponds. Cyprinodontids, poeciliids, and other small fishes are numerous along the shores of these canals, where stands of cattail and beds of bladderwort and southern naiad provide cover. Large populations of centrarchids, Florida gar, and bowfin occur in the open waters. The black crappie and chain pickerel are restricted to such canals in the southern Everglades. Exotic fishes are present but are only locally numerous. A few peripheral fishes, such as the American eel, tarpon, and striped mullet, occur in the open waters of the canals, but most species in these canals are derived from primary and secondary freshwater families (Table 5). Canals on the eastern coastal ridge differ in character from those in natural habitats. Aquatic and riparian vegetation is sparse because of mechanical removal and herbicide spraying. Killifishes, which comprise a high percentage of the biomass and species composition in the Everglades region, are mostly absent from canals along the coastal ridge. The primary reason appears to be the lack of suitable habitat in the deep, steep-sided canals. The use of herbicides may also impact certain species of fishes more than others, affecting the species composition of these canals. The bluefin killifish is the only widespread and numerous killifish in this habitat. The poeciliids have been more successful than the killifishes in urban canals. They inhabit all patches of shoreline vegetation. The mosquitofish is by far the most numerous small fish in the canal system. Historically, centrarchids were the dominant large fishes in the canals in terms of number, diversity, and distribution, and the larger species are still more numerous there than in the marshes and ponds of the southern Everglades. However, several of the smaller centrarchid species are virtually absent from the canal system. The redear sunfish (Lepomis microlophus) appears to be the most abundant centrarchid in these canals, followed by the bluegill (L. macrochims). Both species inhabit open-water areas as adults but, as juveniles, occur in schools along the canal margins. Warmouth inhabit cavities in the limestone walls or hide in the Chara beds, rarely venturing far from cover. The spotted sunfish always nests and generally remains in very shallow water along shore, where it is usually the only adult centrarchid present. Largemouth bass (Microptems salmoides) inhabit all canals, both in the open-water zone and near dense vegetation. The bass is the major piscine predator in the eastern coastal canals because gar and bowfin are usually rare or absent there. The eastern canals support the highest diversity of exotic fishes of any habitat (12 species or 20%). Exotic species now appear to surpass centrarchids in number and biomass in many canals. Except for mangrove streams, LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 289 peripheral fishes are most diverse in eastern coastal canals, comprising 50% of the native species (Table 5). However, the diversity of peripheral fishes there is considerably lower than that of natural coastal rivers, probably because salinity control structures on the canals prevent free access from salt water. The highest number of peripheral species came from the Coral Gables Waterway, the only major canal in the study area without a salinity control structure. Before the dams were improved in the 1950's, more marine fishes occurred in these canals (Kushlan, in prep.), and it is likely that the number and diversity of peripheral species then approached those of natural coastal rivers. Gilmore and Hastings (1983) also found that freshwater penetration by peripheral species in east central Florida rivers was limited by salinity control structures. Small coastal canals, from the Black Creek area south to Florida City, differ in character from the larger drainage canals. These old canals were originally dug for mosquito control and agricultural drainage but are no longer maintained. Most are overgrown by dense stands of the exotic tree, Brazilian pepper (Schinus terebinthifolius). The fish fauna is depauperate, consisting of a few native species and three exotic fishes: the walking catfish, pike killifish, and black acara. In ditches where aquatic vegetation cover is sparse because of heavy shading, the only poeciliid found is the sailfin molly. It is-probable that the mosquitofish and least killifish (Heterandria formosa) are more vulnerable than the larger sailfin molly to predation by pike killifish (Belonesor belizanus) in such open habitats. Within southern Florida, the dollar sunfish and Everglades pygmy sunfish (Elassorna evergladei) are essentially restricted to natural habitats and are not often found in canals in the eastern part of the study area. Several other species that occur in natural areas but are rare in the eastern coastal canals include the bowfin, tadpole madtom, flagfish, and marsh killifish. We collected each of those species only once in eastern coastal canals. Florida gar, lake chubsucker (En'myzon sucetta), and the bullheads are also uncommon along the eastern coastal ridge but do occur in a few canals. It seems likely that the extensive canal system in southern Florida has allowed a number of species that are normally restricted to deep, open waters to extend their ranges into southern Florida. Chain pickerel, channel catfish (Icmlurus punctatus), and black crappie are common in central Florida but occur only in canals in southern Florida. Canals have provided large areas of suitable habitat for centrarchid colonization, and we feel that largemouth bass, bluegill, and redear sunfish populations have been enhanced by these excavations. Certainly, centrarchid populations are much larger in canals than in the marshes of the southern Everglades. Canals act as pathways for dispersal by exotic fishes and by marine invaders, such as tarpon and American eels, that use them to travel many kilometers from salt water. Canals offer the only suitable freshwater habitat in 290 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) southern Florida for schooling fishes like the shad species (Dorosoma cepedianum and D. petenense) (Table 6). Since this habitat is historically recent, it is probable that the freshwater fish fauna of southern Florida has changed in diversity, composition, and numbers in recent times. Canals now provide deep-water habitats year-round, act as pathways for dispersal, and have affected marsh and swamp fish communities by altering hydroperiods through drainage. By acting as dry season refugia they allow many fishes, which would otherwise have been eaten by predators (Kushlan 1976a), to survive and repopulate adjacent habitats when reflooding occurs. Canal excavation, in conjunction with levee construction and water management practices, has been the most consequential factor affecting the distribution of southern Florida freshwater fishes in historic times. Although canal excavation has benefitted a few fish species, it has certainly caused permanent changes in the aquatic habitats and fauna of this region. Coastal Habitats.--The estuaries of the Everglades and Big Cypress Swamp form a complex network of ponds, rivers, and creeks, with interspersed marshes and prairies. The mangrove-lined streams provide pathways for peripheral fishes to enter freshwater areas where they cohabit with typically freshwater species. This mixing results in the highest diversity of native fishes (69 species) recorded from any habitat in the study area (Table 6). Of this total, 43 species or 62.3% are peripheral species. Only two exotic species, the walking catfish and blue tilapia (TUapia aurea), have been found in this region, though it seems likely that the black acara may also be found there since it occurs nearby. Small species are well represented in samples from this region because much suitable habitat is available in numerous shallow-water pools and marshes. The species composition of small fishes is similar to that of the Everglades marsh, except that the goldspotted killifish, gulf killifish, and longnose killifish reside in the mangrove areas but do not enter the marsh. The small-fish fauna is composed of 15 species of poeciliids and cyprinodontids. Many of these are typically freshwater species that enter the headwaters, streams, and pools from the Everglades marsh, whereas others, such as the rainwater killifish and goldspotted killfish, are euryhaline species that invade fresh water only in this region. Most of the small species primarily inhabit coastal marshes and densely vegetated ponds, but they also occur along creek banks around mangrove prop roots. It is only in this area that pairs of several related species occur sympatrically. At several collection sites, we took large series of Lucania goodei and Lucania parva together, and Labidesthes sicculus and Menidia belyllina together. The same phenomenon was observed in coastal areas in northern Florida by Swift et al . (1977). Both Labidesthes sicculus and Lucania goodei occur in freshwater habitats throughout the study area but enter the LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 291 headwaters region only near the upper reaches of the rivers. Menidia beryllina and Lucania parva are two of the most abundant small fishes in brackish water in southern Florida and only enter fresh water in the headwater creeks and pools of the coastal rivers. Neither species penetrates the Everglades marsh to any extent. The mangrove-lined rivers, creeks, and ponds offer deep-water habitats for large fishes. As a result, centrarchids, Florida gar, and bowfin descend into the upper reaches of the river systems, while euryhaline fishes ascend the channels into fresh water. The centrarchids inhabit the smaller creeks under the cover of mangrove prop roots, and also occur in the marshes and ponds. Large schools of Florida gar inhabit the open, slow-flowing reaches of most coastal rivers. We collected ictalurid catfishes only in the upper sections of the rivers, and rarely collected them syntopically With ariid catfishes. Ariids, gobies, and mojarras are common bottom dwellers in the rivers; mullet are numerous at all levels; and needlefishes are common at the surface. Three gamefishes, tarpon, snook, and red drum, ascend the rivers to their upper reaches where the channels intersect the Everglades marsh. However, none of the larger euryhaline fishes enters the shallow Everglades marsh, despite its proximity to the river channels and pools. We made our collections in the headwaters area during the time of heavy runoff from the marshes when the upper reaches of the rivers held only fresh water. As the dry season arrives and freshwater runoff slows, the salinity gradient, aided by tidal influences, moves gradually up the rivers toward the freshwater marsh system. In dry years, many of the river systems may become brackish for several months. The fauna of freshwater marshes on north-central Cape Sable is similar to that of the true Everglades marsh north of Whitewater Bay but is relatively depauperate. Common Everglades species, such as Lucania goodei, Fundulus chgsotus, and most Lepomis were absent. Prior to 1960, the freshwater ichthyofauna there may have been more diverse. Durbin Tabb (pers. comm.) tells of "a substantial freshwater fish population" that included gar, largemouth bass, bluegill, and spotted sunfish. Tabb (pers. comm.) believes that Hurricane Donna in 1960, followed by years of severe droughts, may have adversely affected these populations. Such effects were undoubtedly exacerbated by canal building on the cape. Before the canals were excavated in the 19205 and 19505, the surface waters of Whitewater Bay and the Cape were probably of low salinity during the wet season. Under present hydrological conditions, recolonization by freshwater fishes would be slow following disruptive events like hurricanes, unless the estuarine character of Whitewater Bay is restored. 292 BULLETIN FLORIDA STATE MUSEUM VOL. 31(4) Introduced Fishes Within our study area, 12 species of exotic fishes have established breeding populations (Table 5). The majority (9 species) belong to the Cichlidae, additional species of which are established elsewhere in Florida. The three remaining species belong to the Clariidae, Loricariidae, and Poeciliidae. All of the exotic fishes are native to tropical regions. Two non-native species, Serrasalmus humeralis (Shafland and Foote 1979) and Tilapia zilli (Hogg 1976b), occurred within the study area until their elimination by the Florida Game and Fresh Water Fish Commission. Four ~ species, the koi (carp) (C)ptinus carpio), zebra cichlid (Pseudotropheus zebra), guppy (Poecilia reticulata), and swordtail (X