• TABLE OF CONTENTS
HIDE
 Front Cover
 Abstract
 Resumen
 Introduction
 Acknowledgements & Description...
 Methods
 Species accounts
 Species of doubtful occurrence...
 Hybrids
 Discussion
 Summary
 Literature cited
 Appendix I: Collection site...
 Appendix II: A listing of the voucher...
 Appendix III: An artificial key...
 Back Cover
 Copyright






Freshwater fishes of southern Florida /
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Permanent Link: http://ufdc.ufl.edu/UF00001474/00001
 Material Information
Title: Freshwater fishes of southern Florida /
Series Title: Bulletin of the Florida State Museum
Physical Description: p. 147-344 : ill. ; 23 cm.
Language: English
Creator: Loftus, William F
Kushlan, James A ( James Anthony ), 1947-
Publisher: University of Florida
Place of Publication: Gainesvlle, Fla
Publication Date: 1987
 Subjects
Subjects / Keywords: Freshwater fishes -- Classification -- Florida   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 300-313.
Statement of Responsibility: William F. Loftus and James A. Kushlan.
General Note: Cover title.
General Note: Abstracts in English and Spanish.
 Record Information
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltqf - AAA0756
notis - AEV7374
alephbibnum - 000981394
oclc - 17525580
System ID: UF00001474:00001

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Table of Contents
    Front Cover
        Page i
        Page ii
    Abstract
        Page 147
    Resumen
        Page 148
    Introduction
        Page 149
        Page 150
    Acknowledgements & Description of the study area
        Page 151
        Page 152
        Page 153
        Page 154
        Page 155
        Page 156
        Page 157
        Page 158
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        Page 162
        Page 163
        Page 164
        Page 165
        Page 166
        Page 167
        Page 168
    Methods
        Page 169
        Page 170
        Page 171
        Page 172
        Page 173
        Page 174
        Page 175
        Page 176
    Species accounts
        Page 177
        Page 178
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    Species of doubtful occurrence or persistence
        Page 271
        Page 272
        Page 273
    Hybrids
        Page 274
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    Discussion
        Page 276
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    Summary
        Page 299
    Literature cited
        Page 300
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    Appendix I: Collection site descriptions
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    Appendix II: A listing of the voucher samples and museum catalogue numbers
        Page 336
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    Appendix III: An artificial key to juvenile sunfishes of the genus Lepomis from southern Florida
        Page 343
        Page 344
    Back Cover
        Page 345
        Page 346
    Copyright
        Page 347
Full Text
of the
FLORIDA STATE JVIUSEU1V1 Biological Sciences
Number 4
1987
Volume 31
FRESHWATER FISHES OF SOUTHERN FLORIDA William F. Loftus and James A. Kushlan
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 5BA5
Publication date: 27 November 1987
Price: $7.20


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FRESHWATER FISHES OF SOUTHERN FLORIDA LlBRARY 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 discussed.
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. Floridichthvs 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 al. (1980): Adinia xenica, Floridichthvs carpio, Fundulus similis, Epinephelus itajara, Caranx hippos, Oligoplites saurus, Sphvraena barracuda, Gobionellus smaragdus, and Lophogobius cyprinoides. The centrarchids Lepomis gulosus and Lepomis punctatus were collected at their highest recorded salinity, 12.5 /oo. 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: large centrarchids 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 South 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.
LOFTUS, W.F., AND J.A. KUSHLAN. 1987. Freshwater fishes of southern Florida. Bull. Florida State Mus., Biol. Sci. 31(4):147-344.


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BULLETIN FLORIDA STATE 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 rcsultados del primer estudio sistematico de peces de aguas continentales ("agua dulce") en el sur de la Florida. Antes de este estudio, los rangos de distribucion de muchas especies en el extremo sur de Florida eran poco conocidos o erroneos. Se documenta la existencia de 92 especies de peces continentales y se discuten los factores ecologicos que afectan su status y distribucion.
Se hace tambien una descripcion del rango de distribucion por especie y se da informacion pertinente acerca de su historia natural y ecologia. Se incluye la Iocalizacion y descripcion de areas de recoleccion, una clave artificial para los juveniles de Lepomis sp., asi como una bibliografia sobre peces continentales del sur de Florida.
La recoleccion de especimenes y la revision de literatura permitieron hacer rcgistros de especies no bien conocidas de aguas continentales del sur de Florida. Entre ellas: Carcharhinus leucas, Floridichthvs carpio, Fundulus similis, Epinephelus itajara, Caranx hippos, Oligoplites saurus, Sphvraena barracuda, Gobionellus smaragdus, y Lophogobius cyprinoides. Dos centrarquidos, Lepomis gulosus y Lepomis punctatus, fueron recolectados en aguas cuya salinidad es la maxima registrada para estas especies, 12.5 /oo. Nucva evidencia pcrmitc extender el rango distribucional de 15 especies en el extremo sur de Florida. Previos rcgistros acerca de la existencia de 11 especies en aguas continentales del sur de Florida, son considerados erroneos o dudosos. Se documenta la presencia de 12 especies no nativas, una de las 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 exoticas son mas numerosas en los sistcmas de canales; mientras que muchos ciprinodontoides estan ampliamente representados en la mayoria de los habitats. La abundancia relativa de cstas especies generalmente varia de acuerdo al habitat.
Todas las especies primarias y secundarias de aguas continentales, provienen de zonas templadas de America del Norte. La mayoria de ellas estan ampliamente distribuidas en el sudeste de los Estados Unidos. Todas las especies no nativas establecidas en el area provienen de regiones tropicales y subtropicales.


LOFTUS & KUSHLAN: SO. FLORIDA FRESHWATER FISHES 149
TABLE OF CONTENTS
Introduction...............................................'...................................................................................................149
Acknowledgements......................................................................................................................................151
Description of the Study Area..................................................................................................................151
Methods.........................................................................................................................................................169
Species Accounts.........................................................................................................................................177
Species of Doubtful Occurrence or Persistence..................................................................................271
Hybrids...........................................................................................................................................................274
Discussion.....................................................................................................................................................276
Range Revisions and New Records.................................................................................................276
Faunal Derivation and Salinity Relations.......................................................................................278
Habitat Occurrence and Distribution Patterns............................................................................282
Everglades Marsh Prairies..........................................................................................................282
Everglades Sawgrass Marshes....................................................................................................283
Everglades Alligator Ponds.........................................................................................................283
Big Cypress Swamp.......................................................................................................................284
Canal System..................................................................................................................................284.
Coastal habitats.............................................................................................................................290
Introduced Fishes................................................................................................................................292
Factors Affecting the Fishes..............................................................................................................295
Summary........................................................................................................................................................299
Literature Cited...........................................................................................................................................300
Appendix I. Collection Site Descriptions..............................................................................................314
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 been 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


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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, 1980b).
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.


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ACKNOWLEDGEMENTS
We wish to thank Scott Andree, David Tomey, Carol Hewes, Nancy Deschu, Karen Kronner, and especially Scott A. Voorhees for help in the field 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. Roessler, Paul L. Shafland, 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 Curl, 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


Figure l.~ Map of Florida, south of Lake Okeechobee, showing geographical features.


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Figure 2.-- Map of the study area in southern Florida showing geographical features.


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BULLETIN FLORIDA STATE MUSEUM VOL. 31(4)
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-l 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-l 11 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.


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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 macrochims, 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 Big 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


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30.0-
25.0-
1 u
c 20.0-
5.0-
Figlire 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).


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200.0-j
140.0-
"1 I I I I I I I I I I I
J FMAMJJASOND
Month
Figure 5.-- Mean monthly water levels (above mean sea level) in Shark River Slough, Everglades National Park: 1953-1977 (Rose 1977).


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o 24.0
a>
a
E
22.0
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.A.A. 1979).


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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


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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.


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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 /xmhosxm"^ 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 Everglades marsh rises to 15,000 ^mhosTm"*. 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 mg'' (=PPm)> with similar variation (0.6-12.5 mg'l"^) 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 (Kushlan 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


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Table 1. Major ion concentrations (mgT1) 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
Dry 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
Dry 98.0-534.0 Fish kill


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Table 2. Average and maximum concentrations (mgT ) 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 0.0- 0.0
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


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Table 3. Nutrient concentrations (mgT ) 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 Dry
Fish kill Nitrate + Nitrite Wet Dry
Fish kill Total Nitrogen Wet Dry
Fish kill Orthophosphate Wet Dry
Fish kill Total Phosphorus Wet Dry
Fish kill Total Carbon Wet Dry
Fish kill Total Organic Carbon Wet Dry
Fish kill
0.02 0.24 0.50 -1.60
0.00 0.08 0.00 0.43
0.53 -2.31 0.57 -13.00
0.00 -0.001-
0.020 0.107
0.00 0.04 0.002- 0.20
42.00-101.00 47.00 -136.00
1.00 62.00 4.00 73.00
0.01 -0.82 0.06 -1.10
0.01 -0.47 0.02 0.49
1.00 1.10
4.08 3.10
0.00 -0.110 0.004- 0.013
0.010- 0.036 0.013- 0.260
4.40-75.00 48.00-98.00
16.00-50.00 19.00-49.00
0.02 0.02
0.01(NO2); 0.10(NO3) 0.017(NO2); 0.10(NO3)
Nf02
0.12(NO2)
2.0(NO3f
0.87 0.87
0.00 0.08 13.00
0.15 0.90


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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 Cypress 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 {Eleocharis cellulosa) or beakrush (Rhynchospora tracyi), and maidencane {Panicum hemitomon) is also locally common. Spider lily (Hymenocallis latifolia), white water lily (Nymphaea odorata), floating heart (Nymphoides aquatica), pickerelweed (Pontederia lanceolata), and arrowhead (Sagittaria lancifolia) 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 (Utricularia purpurea). In Taylor Slough and adjacent uplands, intermittent marshes are dominated by sawgrass, muhly (Muhlenbergia filipes), and black rush (Schoenus nigricans).
Sawgrass marshes (Fig. 8) occupy slightly higher ground than marsh prairies and are usually underlain by deep peat substrates. This habitat is dominated by sawgrass that, in many areas, forms vast expanses of nearly monospecific stands up to 3 m tall. Arrowhead, arrow arum (Peltandra


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Figure 8.- (A) Dense Everglades sawgrass marsh at collection site #54; (B) Everglades marsh prairie at collection site #54.


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virginica), and the fern (Blechnum semdatum) sometimes occur within the sawgrass marsh. Buttonbush {Cephalanthus occidentalis), willow (Salix caroliniana), and cocoplum {Chiysobalanus icaco) are woody shrubs that are sometimes present in the sawgrass marshes. Standing water recedes rapidly from sawgrass marshes during the dry season, but the deep peat substrate acts as a sponge to hold ground water for a long period.
Alligator ponds in the southern Everglades occupy basins in the limestone bedrock (Fig. 9). Water depths average 1-2 m during the wet season. The temperature and oxygen regime has been characterized by Kushlan (1979b), as have the limnological characteristics of similar habitats in the Big Cypress Swamp (Kushlan and Hunt 1979). Everglades ponds are surrounded either by typical marsh prairie or sawgrass vegetation or by hardwood trees, especially willows. The pond surface and water column can either be open or occupied by spatterdock (Nuphar luteum), southern naiad {Najas guadalupensis), and bladderworts. Willow forests surrounding ponds often include pickerelweed, sawgrass, buttonbush, alligator flag {Thalia geniadata), and pond apple {Annona glabra). Such ponds are the naturally occurring deep-water habitats of the Everglades and are originated and maintained by the American alligator {Alligator mississippiensis) (Kushlan 1974c).
The Big Cypress Swamp is a complex mosaic of swamp, marsh, and upland communities (Craighead 1971). The major substrate in the Big Cypress is sand overlain by marl in areas with short hydroperiods or by peat in deeper water areas. The most characteristic plant community is cypress forest occurring in strands, domes, or scrub, and dominated by bald cypress {Taxodium distichum) and pond cypress {T. ascendens) (Fig. 10). Swamp hardwoods such as popash {Fraxinus caroliniana), willow, buttonbush, and red maple {Acer rubrum) are common subcanopy species in the swamp. Vast areas are occupied by sparse marsh prairies, and alligator ponds are common (Fig. 10). The large strands have extensive areas of deep ponds and pond apple sloughs. Water depths during the wet season vary from 0.3 m in the dwarf cypress areas to nearly 2 m in the center of cypress sloughs or ponds.
Canals and borrowpits are artificial deep-water habitats constructed for drainage, levee fill, or mining operations. All natural drainages of any significance along the extreme southeastern coast of Florida have been replaced by canals (Beck 1965). Canals through the Everglades or Big Cypress Swamp usually are bordered on one side by natural aquatic habitats, and on the other side by a levee or road (Fig. 11). The sloping canal edges are lined by marsh or swamp vegetation, particularly sawgrass, willow, or cattail {Typha latifolia). Submerged vegetation is normally abundant along the margins of these canals. In the Big Cypress Swamp canals, Salvinia rotundifolia and Pistia stratiotes are locally abundant surface plants. On the eastern coastal ridge, canals and borrow pits have steep-sided banks that reduce the available littoral


Figure 9.- (A) Everglades alligator willow-pond near collection site #53; (B) an Everglades alligator marsh-pond near collection site #53.


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zone. These canals range from 2 to 7 m deep and are 3 to 10 m wide (Fig. 11). Riparian cover is normally sparse. Many urban canals are bordered by tall Australian pines (Casuarina sp.) that shade the water surface, reducing the amount of submerged vegetation in the canals. In both types of canals, large sections may be choked by Hydrilla verticillata and Najas guadalupensis and the water surface covered by water hyacinth, Eichornia crassipes. Because these plants obstruct water flow in the canals, both chemical and mechanical methods of removal are frequently employed.
Freshwater marshes and swamps give way to mangrove swamps near the coast (Tabb et al. 1967; Craighead 1971) (Fig. 12). Most coastal mangrove swamps are estuarine with salinities varying from hypersaline in the dry season to completely fresh during the wet season. In the headwaters, where coastal streams meet the Everglades marsh, red mangrove {Rhizophora mangle) occurs along the edges of the small finger creeks (Fig. 12). These creeks coalesce into progressively larger streams toward the coast. In addition to red mangrove, the streams are often bordered by willow, pond apple, cattail, and sawgrass. Inland, the habitat between the streams consists of marshes of sawgrass, cattail, cordgrasses (Spartina spp.), and black rush (Juncus roemerianus). Farther seaward, mangrove swamp predominates, and red mangrove-lined pools are common. The substrate in these swamps is deep mangrove peat. During highwater periods, when water outflow from the marshes results in the streams being completely fresh, water depths range from 1 to 2 m, and the bottom is often scoured to the bedrock.
The Cape Sable region is the southwestern tip of the Florida mainland. The area supports mangrove-dominated wetlands, lakes and ponds, of which most are brackish or saline. However, on the northcentral portion of the cape is a small basin with freshwater marshes similar in character to those of the lower Shark River Slough. These marshes seem to result from the retention of localized rainfall by the poorly drained marl substrates. The marshes consist of large areas of Eleocharis cellulosa, interspersed by stands of sawgrass and mangrove clumps. Pools and shallow channels bordered by cattails are common. Additional descriptions of specific sections of the study area are provided in Appendix I.
METHODS
Because of the wide variety of freshwater habitats in southern Florida, we used several sampling techniques. In the Everglades marsh, conventional sampling techniques, such as seining, were useless because of dense plant and periphyton cover. Representative samples were obtained with rotenone-based




Figure 10. Cypress habitats: (A) Roberts Lake cypress strand near collection site #35; (B) Cypress prairie near collection site #36; (C) Tamiami Canal dissecting cypress swamp near collection site #6.




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Figure 11- Major artificial habitats: (A) Tamiami Canal and water control structure in the Everglades marsh near collection site #40; (B) Bird Road Canal on the urbanized coastal ridge near collection site #152; (C) Sweet Bay Pond along Park Road at collection site #108; (D) Park Road culvert at collection site #100.


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Figure 12.- Mangrove habitats: (A) Aerial photograph of Broad River near collection site #138; (B) mangrove-lined creek bordered by freshwater marsh at collection site #139, near Rookery Branch.


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toxicants (Noxfishc and Pronox-Fishc) and with Smith-Rootc electroshocking units1. The toxicant was applied by using a hand-sprayer to mix it well into the water column. Rotenone was effective in all habitats, but we used it sparingly. We obtained additional records of marsh fishes by using pull-up traps, throw traps (Kushlan 1981), cast nets, and angling. Quantitative information on relative abundance of fishes was obtained from the traps. We sampled mangrove-lined creeks and pools in the headwaters region with gill nets and cast nets in the main channels, and with rotenone in the feeder creeks. Electrofishing was very effective in these streams at night when we shocked fishes as they rested near the bottom. We collected fishes from road culverts and small ditches using rotenone, dip nets, and electrofishing. Canals and rockpits proved more difficult to sample effectively, as the steep banks and deep water precluded the use of most gear. We obtained the best results using a combination of gill nets, electrofishing, and limited applications of rotenone along the shoreline.
We sometimes relied on sight observations to document the occurrence of certain fish species, especially larger fish that were difficult to capture. Sight observations were made in two ways: using polaroid sunglasses and binoculars, we walked along canal and rockpit banks while recording the fishes observed; or, in selected canals and rockpits, observers snorkeled and recorded the observed species on underwater slates. In the clear, shallow waters of southern Florida, experienced observers can easily and unequivocally identify by sight the rather limited number of fish species present, so that little error is associated with this technique.
We collected fishes at 181 sites. The fishes were preserved in 10% buffered formalin and were later transferred to 40% isopropanol. Because of the large number of collection sites, we could not save all specimens. Instead, we designated 39 voucher sites approximately 12-16 km apart throughout the study area to provide a representation of the freshwater ichthyofauna of the region (Fig. 13). The voucher locations were either single collection localities or a series of nearby collection sites in similar habitats along a continuous watercourse. The collection sites are listed and described in Appendix I; the collection sites included in each voucher location are listed in Appendix II. For each collection site, we include the precise location by township, range, and section, the date(s) of collection, method(s) of collection, and any site-specific habitat information. All species of fishes taken at each site are listed; those species observed are indicated by an asterisk following the species number. We do not report the numbers and lengths of each species taken at each location because the large number of specimens precluded individual enumeration and
Reference to trade names does not imply endorsement by the National Park Service, U.S. Department of the Interior.


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Figure 13.-- Locations by number of the 181 collection sites and 39 voucher sites within the study area.


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measurement. Because physical features within each habitat type are usually quite uniform, only when a collection site departed from the overall description given for that habitat do we provide general habitat information in Appendix I. Unless otherwise noted, salinities at all collection sites were 0/oo, as measured by an American Optical0 refractometer. We took salinity measurements both at the surface and near the bottom in rivers and ponds to detect salinity wedges. This procedure was not necessary in very shallow ponds and marshes.
We attempted to collect large series of specimens at each voucher location, and we also saved rare or unusual specimens from collection sites outside of the voucher locations. All voucher specimens from this study have been deposited in the Florida State Museum, University of Florida, Gainesville. Several centrarchid specimens were deposited at the University of Michigan Museum of Zoology, Ann Arbor. Catalogue numbers for the specimen lots are listed in Appendix II in conjunction with the appropriate voucher samples.
For all fish identifications we followed Carr and Goin (1955), Brown (1957), Dawson (1969), and Eddy and Underhill (1978). Several centrarchid and cichlid identifications that proved difficult were confirmed by C.R. Gilbert and R.M. Bailey. Existing keys to southern Florida freshwater fishes proved adequate, except for the juveniles of Lepomis. We have constructed an artificial key to their identification (Appendix III). The nomenclature used in this paper follows Robins et al. (1980) for both common and scientific fish names.
SPECIES ACCOUNTS
We present species accounts for all fishes recorded from fresh water in extreme southern Florida. The species accounts are ordered by family and follow the format of Gilbert and Kelso (1971). In the heading for each account, we give the scientific and common names and the classification of the fish as a primary (I), secondary (II), or peripheral (III-VI) freshwater species (Myers 1938, 1949, 1951). We also list the pertinent voucher sites (VS) at which the species was collected. An asterisk next to the site number indicates a sight record.
Each map shows the collection sites at which the species was taken, with solid symbols representing specimen records and open symbols indicating sight observations. To present the freshwater range of each species as completely as possible, the distribution maps include a number of incidental observations from locales not designated as collection sites. The maps also include records from previous studies and the references for those records if the locations differed from those at which we recorded the species.


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Each account contains all past distributional data from our area of study, a regional overview of distribution in adjoining areas of southern Florida, a summary of findings from our sampling, a discussion of habitat, relative abundance, and pertinent ecological data. In the accounts of euryhaline species collected within the study area, we cite all other southern Florida freshwater records from the literature, even if the records were from localities at which salinities slightly exceeded 0.0/oo (e.g. Gunter and Hall 1963a, 1963b, 1965). If a subspecific epithet is recognized for the species in our region, it is given in the account. We have also provided distributional information from data obtained during a fish monitoring program in the Everglades from 1966 to 1972 (Kushlan 1980a). Notes on species whose reported occurrence or persistence in our region is doubtful are presented separately in a section following the species accounts.
CARCHARHINIDAE -- requiem sharks
1. Carcharhinus leucas (Valenciennes) bull shark (VI)
VS 15 Figure 14
We collected two small specimens of the bull shark in a gill-net set during early November in the main channel of Broad River, at the junction of a small tributary 22 km from its mouth. One juvenile male specimen was saved. Its lengths were 58.0 cm precaudal, 65.5 cm fork, and 76.5 cm total. The lengths of both specimens were similar and were in the range for newborn bull sharks from the Florida Gulf coast (Clark and von Schmidt 1965). This is the second time that specimens of the bull shark have been collected in fresh water in extreme southern Florida, and it represents a new freshwater record for the area (Burgess and Ross 1980). The first specimen was taken in Watson River in 1966 (Tabb et al. 1974). Odum (1971) also observed sharks, most probably this species, in North River. Two newborn specimens of C. leucas were taken in a gill net set in Shark River in May 1980 at 0.8/oo salinity (D. Wright and T. Kranzer pers. comm.), just downstream from the freshwater section of this creek. The small size of the freshwater specimens suggests that the Everglades estuaries may serve as birthing and nursery grounds for the bull shark, as does the Indian River Lagoon system to the north (R.G. Gilmore pers. comm.). Our collection of newborns in November differs from Clark and von Schmidt's (1965) finding that spring is the season of birth.
We did not take C. leucas in our other river samples, although it undoubtedly enters fresh water in other Florida coastal areas (Gilmore 1977). Bull sharks are noted for their ability to ascend long distances into fresh water, occurring in rivers, lakes, and estuaries along the Atlantic, Gulf, and Caribbean


Carcliarhinus leucas
Figure 14.-- Distribution of Carcharhinus leucas and Dasvatis sabina in fresh water in southern Florida. Open symbols signify sight records. 1 = Odum (1971); 2 = Tabb et al. (1974).


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coasts (Gunter 1938; Bigelow and Schroeder 1948; Miller 1966; Thorson et al. 1966; Swift et al. 1977; Burgess and Ross 1980).
DASYATIDAE stingrays
2. Dasyatis sabina (Lesueur) Atlantic stingray (VI)
VS 24* Figure 14
A stingray that we observed in a mud-bottomed pool in Taylor River was most likely this species, because it is the only North American stingray that commonly enters fresh water (Ross and Burgess 1980). Freshwater specimens were collected in our study area in 1966 by Tabb et al. (1974), and we believe that D. sabina is more widespread in estuarine and fresh waters than our collection data indicated. This species has previously been reported from fresh water in the St. Lucie (Gunter and Hall 1963a) (0.2-0.3/oo) and the Caloosahatchee rivers (Gunter and Hall 1965) and in the Indian River region (Gilmore 1977).
LEPISOSTEIDAE gars
3. Lepisosteusplatyrhincus De Kay Florida gar (II)
VS 1, 2, 3, 4*, 5*, 6, 7, 8, 9,10,12, 13*, 15, 16*, Figure 15
21, 22, 23, 24, 25, 26, 27, 28*, 29, 31, 32, 37
The Florida gar is a common resident of southern Florida's fresh waters, where it is perhaps the most abundant large fish species in deep-water habitats. It occurs in all habitats in Lake Okeechobee (Ager 1971) and ranges southward through the Everglades Water Conservation Areas (Dineen 1974) and Big Cypress Swamp into the southern Everglades. The Florida gar is most abundant in well-established canals and rockpits, alligator ponds, and mangrove-lined headwater creeks. Belshe (1961) stated that gar were uncommon in urban and agricultural canals, and our findings support his conclusion. The canals of eastern Dade County held far fewer gar than canals in the Everglades region. Gar occur in the open marshes of the Everglades year round. During the wet season, they are widely dispersed throughout the marshes and are difficult to capture. As water levels decrease during the dry season, gar concentrate in alligator ponds (Kushlan 1974a), and it is then possible to take several hundred from a small pond. Each pond concentrates gar from large areas of marsh and serves as a dry season refuge, as do canals in the northern Everglades (Dineen 1974). During the dry season, such dense concentrations of gar have been reported to be susceptible to parasitic infestations of Argulus sp., which sometimes results in high mortality


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Figure 15.-- Distribution of Lepisosteus platvrhincus and Ami a calva in fresh water in southern Florida. Open symbols signify sight records. 1 = Tabb et al. (1974); 2 = Tabb and Manning (1961); 3 = Mark Hudy (pers. comm.).


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(Kolipinski 1969). The gar uses its swim bladder for aerial respiration (McCormack 1967), enabling the fish to survive low oxygen conditions during the dry season.
We rarely collected small gar in our samples, nor were many collected during the 1965-1972 sampling program in the southern Everglades (Kushlan 1980a). Dineen (1974) and Ager (1971), despite their extensive sampling programs, have also commented on the difficulty of collecting small gar. We did collect a series of juveniles, ranging from 190 mm to 210 mm TL, from sawgrass strands in the spring, indicating that this habitat may serve as a nursery for the young. However, we still lack adequate data on the early life history of L. platyrhincus in the Everglades.
L. platyrhincus occurred in most of the coastal rivers sampled during this study and was especially numerous in Shark River and Squawk Creek in winter. Odum (1971) and Tabb and Manning (1961) stated that Florida gar became abundant in the Everglades mangrove belt during the wet season; however, we often observed this species in the mangrove region even during the dry season when waters were quite saline. Kilby and Caldwell (1955) reported several sight observations in this region in habitats with estimated salinities in excess of 25/oo. For this reason, we would classify the Florida gar as a secondary freshwater fish in southern Florida. Other authors have considered L. platyrhincus to be a primary freshwater fish on the basis of their collections (Suttkus 1964; Swift et al. 1977). Osmoregulation by the Florida gar was studied by Zawodny (1975).
AMIIDAE bowflns
4. Amia calva (Linnaeus) bowfin (I)
VS 1,2, 8*, 22* Figure 15
The bowfin reaches the southern limit of its range in extreme southern Florida, where it is rarely abundant (Burgess and Gilbert 1980). Bowfin occurred in large numbers in the study area only in L-67E Canal and in the Everglades portion of Tamiami Canal. These Everglades canals seemed to provide very suitable habitat, and we were able to capture numerous specimens by electrofishing. Nearly all of the fish collected were large adults. We collected only one small (67.5 mm TL) bowfin in southern Florida during five years of sampling. Dineen (1974) also had difficulty collecting small bowfin in the Everglades Water Conservation Areas.
Many of our records for bowfin in southern Florida were observations of individuals in deep-water habitats, especially canals. We have only four observations of bowfin in the Everglades marsh. Dineen (1968) collected a large number of bowfin in northern Everglades canals and marshes. He found


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that Amia calva comprised a major portion of the biomass in the canals, and that it was one of the first large fishes to be found in newly flooded marshes. Neither of these situations appears to hold for the southern Everglades.
The bowfin is better able to survive Everglades dry season conditions than many other native species. It is capable of aestivating (Neill 1950), and Dineen (1974) reported finding live bowfin buried in the sediment of freshly-dried Everglades marshes. This adaptation may allow the fish to survive a short dry-down. In addition, the bowfin is capable of using the swim bladder for absorbing atmospheric oxygen, an important adaptation in oxygen-deficient waters during the dry season. We have also found that the bowfin is an important predator on large centrarchids in Everglades canals during the dry season.
ELOPIDAE tarpons
5. Elops saunis Linnaeus ladyfish (VI)
VS 15,16, 22 Figure 16
This species is a common inhabitant of salt and brackish waters along the Florida coast. Ladyfish enter fresh water in most coastal rivers that drain the Everglades marsh. We caught several large series of specimens in gill nets set in the main river channels. Our collections included adults, which had been poorly represented in most earlier collections from Florida fresh water (Odum 1971). Juvenile ladyfish had been previously collected in southern Florida fresh waters in mangrove-lined ponds and lakes (Tabb and Manning 1961). Odum (1971) collected many juveniles, all less than 346 mm SL, in the mangrove zone of North River and remarked on the river's importance as a nursery for ladyfish. The same is probably true of most of the rivers that drain the southern Everglades.
6. Megalops atlanticus Valenciennes tarpon (VI)
VS 1*, 2, 22 Figure 16
The tarpon is a widespread inhabitant of southern Florida fresh waters, where it is restricted to deep-water habitats. We took only a few specimens during our sampling, even though adult and juvenile tarpon are frequently taken by anglers in coastal freshwater rivers. Tarpon penetrate the Everglades region by using canals during high-water periods. They occur in freshwater canals throughout the Everglades, the Big Cypress Swamp, and along both coasts (Kushlan and Lodge 1974) but are relatively uncommon there. We have a number of sight records from the larger canals in our study area, especially Tamiami Canal, C-lll, and L-31N Canal. A population of


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Figure 16.-- Distribution of Megalops atlanticus, Elops saurus, and Anguilla rostrata in fresh water in southern Florida. Open symbols signify sight records. 1 = Odum (1971); 2 = Tabb and Manning (1961,1962); 3 = Tabb et al. (1974).


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adults inhabited L-67E Canal until killed by freezing temperatures in January 1977. Most of the fish exceeded 1.5 m in length. Tarpon were not seen again in the canal until July 1978, and they persisted through the end of our study. We collected and photographed a 1.0 m TL specimen there on 15 January 1981. Ager (1971) reported sighting tarpon in Lake Okeechobee, and Dineen (1974) found large tarpon in canals in Everglades Conservation Area 3-A.
During high-water periods, tarpon apparently can move across inundated marshes to reach deeper bodies of water. Their irregular appearances in isolated borrow ponds, such as those at Anhinga Trail, are evidence of these movements.
The American eel is one of the few catadromous fishes in southern Florida and is the only one that commonly inhabits the southern Everglades. It was fairly common in our collections from rockpits and canal margins in the upper Shark River Slough. The eels may use the deeper waters of airboat trails to reach these inland sites 50-60 km from salt water, but it is more likely that the system of drainage canals provides the means of access to the Shark River Slough. Eels also penetrate into the northern Everglades where they commonly occur in canals (Dineen 1974).
The American eel inhabits headwater rivers and creeks where we collected them mainly from undercut banks. Odum (1971) found eels in similar habitats in North River. We also collected A. rostrata from drainage canals along the east coast where they were quite numerous. In all habitats, eels occur in cavities in the rocky sides of rivers and canals during daylight hours. It is likely that A. rostrata occurs in all streams and canals with access to salt water in southern Florida (Kushlan and Lodge 1974). Our collections show that A. rostrata has a larger range in extreme southern Florida than that presented by Lee (1980a).
ANGUILLIDAE freshwater eels
7. Anguilla rostrata (Lesueur) American eel (V) VS 2, 7,15, 21, 27, 33, 37, 39
Figure 16
CLUPEIDAE herrings
8. Dorosoma cepedianum (Lesueur) gizzard shad (IV) CS 155, 172*
Figure 17
The gizzard shad is a rare species in southern Florida fresh waters, where it is restricted to the canal system. It is apparently much more common in lakes and canals in central Florida (Ager 1971; Wegener and Williams 1974;


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Figure 17.- Distribution of Dorosoma cepedianum, Dorosoma petenense, and Anchoa mitchilli in fresh water in southern Florida. 1 = Odum (1971); 2 = Tabb and Manning (1961); 3 = Hogg (1974); 4 = Mark Hudy (pers. comm.).


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Gilmore 1977). The only D. cepedianum collected during this study was a large, recently dead specimen found in C-100 Canal. We also observed a school of approximately 50 shad, all exceeding 200 mm SL, in a Homestead canal. We presume that these shad were D. cepedianum because they exceeded the maximum size reported for D. petenense (Stevenson 1976; Burgess 1980f). Additional southern Florida specimens of D. cepedianum have been taken by Hogg (1976a) in Snapper Creek Canal and by Dineen (1974) in northern Everglades canals. These data extend its known range as given by Megrey (1980).
9. Dorosoma petenense (Giinther) threadfin shad (IV)
VS 28 Figure 17
During the study, we collected only one series of threadfin shad, from the open waters of a deep canal. All were juveniles from a single large school. D. petenense does not occur in the Everglades marsh or in the coastal rivers, and it has not been reported from large drainage canals in the northern Everglades (Dineen 1974). We are aware of only one other record from our study area, an east coast borrow pond (Mark Hudy pers. comm.). In the St. Lucie estuary, Gunter and Hall (1963a) also took only juveniles at low salinities. The paucity of shad in our samples may be due to their patchy distribution pattern, typical of schooling species. For that reason, we may have missed the threadfin and gizzard shads in some canals. The threadfin shad has a larger range than that shown by Burgess (1980f).
ENGRAULIDAE anchovies
10. Anchoa mitchilli (Valenciennes) bay anchovy (VI)
Not collected Figure 17
This widespread species was considered to be the most abundant fish in the brackish waters of Everglades National Park by Tabb and Manning (1961), who also collected it in fresh water. Odum (1971) found A. mitchilli in North River, but the salinity of the site was not reported. The bay anchovy has also been taken in fresh water in the St. Lucie River (Gunter and Hall 1965), from the Peace River (Wang and Raney 1971), and in the Indian River area (Gilmore 1977). We did not collect this species during our sampling.


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ESOCIDAE pikes
11. Esox niger Lesueur chain pickerel (I)
VS 1, 2*, 7* Figure 18
The chain pickerel is a rare fish in extreme southern Florida. Briggs (1958) listed E. niger as ranging to the tip of the peninsula, but few records of the fish exist for Everglades National Park. We collected several specimens, all from the northern border of the study area in Tamiami Canal. We also observed this species in borrow pits and canals in Shark Valley and in L-67 Canal Extended. It appears that these canals mark the southern limit of the chain pickerel's range. Dineen (1968) stated that E. niger was common in canals in Everglades Water Conservation Area 2, but it had not become established in Water Conservation Area 3 because the species required a nearby deep-water marsh for spawning. Such deep-water marshes are uncommon south of Tamiami Canal. Heavy predation may affect its numbers at the northern border of our study area.
CYPRINIDAE carps and minnows
12. Notemigonus crysoleucas (Mitchill) golden shiner (I)
VS 1, 3, 4*, 5, 7,10,13,17,24, 26*, 27,28,29, 30, Figure 18
31,32,33,35,36, 39
This important bait and forage species is the most abundant and widespread cyprinid in southern Florida. N. ciysoleucas occurs in Lake Okeechobee (Ager 1971) and is common in the northern Everglades where it moves far into the marsh following wet season inundation (Dineen 1974). The golden shiner appears to be the southern Florida cyprinid best adapted to environmental conditions in the Everglades and Big Cypress Swamp. The preferred natural habitat appears to be alligator ponds, although we have occasionally collected juvenile shiners in marshes. This species is particularly numerous and attains its largest size in canals and rockpits, where it inhabits open, midwater areas. The golden shiner also occurs in mangrove-lined creeks and ponds in the headwaters region.
13. Notropis maculatus (Hay) taillight shiner (I)
VS 35; CS 82,161B Figure 19
In southern Florida, the taillight shiner ranges from Lake Okeechobee (Ager 1971) southward to the southern Everglades, where it and N. petersoni


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Figure 18.- Distribution of Esox niger and Notemigonus erysoleucas in fresh water in southern Florida. Open symbols signify sight records.


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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 for the shiner may have been more suitable. We collected it in L-31W Canal, C-l 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 (1980b). 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).
Two 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 Caloosahatehee 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). N. 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 TV. petersoni in 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


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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.).


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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 (1980b).
CATOSTOMIDAE suckers
15. Erimyzon 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 common 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).


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ICTALURTDAE 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 Everglades. We collected it in marsh prairies, sawgrass marshes, alligator ponds, headwater streams, and cypress swamps. In the northern Everglades, Dineen (1974) found /. 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 ariid catfishes. In those habitats, we normally took /. 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. /. 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; Lagler et al. 1977). We often observed /. 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. Kushlan (1974a) observed a similar behavior in Big Cypress Swamp populations of T. 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 /. 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


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Figure 20.- Distribution of Ictalums natalis and Ictalurus nebulosus in fresh water in southern Florida. Open symbols signify sight records. 1 = Hogg (1974).


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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 abundant than I. natalis 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 I. n. marmoratus, although this species is in need of taxonomic review (C.R. Gilbert pers. comm.)
18. Ictalurus punctatus (Rafinesque) channel catfish (I)
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, I. 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). /. punctatus 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)
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. gyrinus to be uncommon,
VS 1*, CS 82*
Figure 21
VS 1, 4, 10,15
Figure 21


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Figure 21.- Distribution of Ictalurus punctatus and Noturus gyrinus in fresh water in southern Florida. Open symbols signify sight records. 1 = Tabb and Manning (1961).


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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 Cypress Swamp, and Kushlan (1974a) did not take it during his study of an alligator hole in the swamp. If N. gyrinus does occur in the Big Cypress Swamp, the population must be small.
Our sampling data suggest that N. gyrinus 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. batrachus, 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


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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 Clarias 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. batrachus 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 1974a). 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. batrachus 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. batrachus 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.


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ARIIDAE sea catfishes
21. Alius felis (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 Alius 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 of A. felis and Bagre marinus 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) (0.15-0.23/oo) 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 Alius felis but did not approach it in abundance. Odum (1971) had previously collected B. marinus in fresh water in the North River, where it was out-numbered eight to one by A. felis. Additional freshwater records for B. marinus have come from the Caloosahatchee River (Gunter and Hall 1965). It appears that this euryhaline catfish is an uncommon inhabitant in southern Florida 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).
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.
LORICARIIDAE armored catfishes
23. Hypostomus sp. suckermouth catfish (I) Exotic Not collected
Figure 23


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Figure 23.- Distribution of Arius felis, Bagre marinus, and Hypostomus sp. in fresh water in southern Florida. 1 = Courtenay et al. (1974).


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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. Strongylura marina (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 1980h). 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 5. notata 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 (0.25/oo) in southern Florida was of two specimens collected in the St. Lucie River (Gunter and Hall 1963a). However, Gilmore (1977) found S. notata 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.


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Figure 24.- Distribution of Strongylura marina, Strongylura notata, and Strongylura timucu in fresh water in southern Florida. Open symbols signify sight records. 1 = Odum (1971); 2 = Tabb et al. (1974).


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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, our 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 Figure 25
This euryhaline killifish commonly occurs along the Gulf coast of Florida, where 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 freshwater 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 seemed to be most common in mangrove-lined pools and streams in the headwaters region. We collected our largest series of specimens from such habitats.


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Figure 25.- Distribution of Adinia xenica, Cyprinodon variegatus, and Floridichthys carpio in fresh water in southern Florida. Open symbols signify sight records. 1 = Tabb and Manning (1961).


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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. Cyprinodon variegatus Lacepede sheepshead minnow (VT)
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. variegatus also 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. variegatus 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 marl 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. variegatus in southern Florida has been provided by Rancy 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 carpio. 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. carpio. 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


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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. variegatus by Johnson (1974). Johnson (1974) did find evidence for a distinct south Florida race.
Martin (1972) discussed factors determining local distribution of C. variegatus in Texas. He collected it in areas characterized by shallow water, sparse stands of rooted vegetation, minimal wave action, and salinities greater than 10/oo. It was frequently absent from similar situations at salinities less than 10/oo. He concluded that the absence of C. variegatus in 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, Micropterus salmoides, Ictalums natalis, and other primary species. In the southern Everglades, primary freshwater fishes do not appear to limit the establishment of C. variegatus 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. variegatus in Florida fresh water. Our observations tend to support his contention.
C. variegatus 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 (Giinther) 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 jF. carpio in a rotenone sample from a mangrove-lined freshwater pool along the North River. F. carpio 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.


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30. Fundulus chrysotus (Giinther) 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. chrysotus 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. chrysotus 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. chrysotus 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 15.0-24.7/oo along the Florida Gulf coast.
Kushlan (1973a) found differing responses to dry-down between F. chrysotus 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. chrysotus 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.


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Figure 26.- Distribution of Fundulus chrysotus in fresh water in southern Florida. Open symbols signify sight records.


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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. chrysotus 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 Cyprinodon variegatus, it is most numerous in shallow waters over a pale substrate. F. confluentus also exhibits burying behavior when threatened. Harrington (1959) showed that F. confluentus 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 jF. c. confluentus.
32. Fundulus grandis 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


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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).


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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 1980a), 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


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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-lll 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-lll Canal. F. similis 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.).


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35. Jordanella floridae (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 1980b), the flagfish is widespread and locally abundant in southern Florida fresh water. /. floridae 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 12.0/oo. 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 of/, floridae 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 of/, floridae and its behavior in aquaria.
Eddy and Underhill (1978) erroneously reported that /. floridae 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, Garmanella, for the Yucatan fish, which does slightly resemble /. floridae and may be closely related (C.R. Gilbert pers. comm.)


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Figure 28.- Distribution of Jordanella floridae in fresh water in southern Florida.


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36. Lucania goodei Jordan bluefin killifish (II)
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 affinis, Heterandria formosa, 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 12.5/oo. 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 1980b) 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).


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Figure 29.- Distribution of Lucania goodei, Lucania parva, and Rivulus marmoratus in fresh water in southern Florida. 1 = Tabb and Manning (1961).


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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 marmoratus Poey rivulus (IV)
Not collected Figure 29
R. marmoratus 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. marmoratus 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 1980d). Several authors have reported R. marmoratus 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 JR. marmoratus 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.


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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-lll. We collected several large series ofB. belizanus from freshwater 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 35/oo (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 affinis, 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.


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Figure 30.-- Distribution of Belonesox belizanus in fresh water in southern Florida. 1 = Courtenay et al. (1974).


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40. Gambusia affinis (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. affinis 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 Hall 1963a). We have frequently collected and observed G. affinis 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 80/oo (R.G. Gilmore pers. comm.).
In the southern Everglades, we found G. affinis 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. affinis 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. affinis 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. affinis 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. affinis is primarily a surface-dwelling fish, small groups moving constantly about the open surface waters. G. affinis 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


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Figure 31.-- Distribution of Gambusia affinis and Gambusia rhizophorae in fresh water in southern Florida. 1 = Rivas (1969). Marine sites are indicated by 2.


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often observed G. affinis 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. affinis 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 1974a) all combine with a long reproductive season to make G. affinis 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 151a 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. rhizophorae 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. rhizophorae 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


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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. rhizophorae 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. formosa 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. formosa 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 affinis. 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. formosa attain greater maximum sizes than do males, which are among the world's smallest vertebrates at maturity (Breder and Rosen 1966).


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Figure 32-
- Distribution of Heterandria formosa in fresh water in southern Florida.


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43. Poecilia latipinna (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 Cypress Swamp, southern Everglades, and eastern coastal canals. P. latipinna 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.).


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Figure 33.- Distribution of Poecilia latipinna in fresh water in southern Florida.


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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 1980a). 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 beryllina) 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 1980c).
45. Menidia beryllina (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) (0.14/oo) 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. beryllina is also numerous in freshwater habitats along the headwaters of coastal streams in southern Florida. Large schools of M. beryllina 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. beryllina to be the most abundant fish in the North River system, and


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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. beryllina 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 of M. beryllina.
CENTROPOMIDAE snooks
46. Centropomus ensiferus Poey swordspine snook (VI)
Not collected Figure 35
C. ensiferus is apparently uncommon in North American fresh water, where it is limited to extreme southern Florida (Burgess 1980b). 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 1980b). 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 1980c), 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 1980c). 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.


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Figure 35.- Distribution of Centropomus ensiferus, Centropomus parallelus, Centropomus pectinatus, Centropomus undeeimalis, and Epinephelus itajara 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).


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48. Centropomus pectinatus 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 1980d). 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 pectinatus, 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 undeeimalis 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 1980e). 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. undeeimalis 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 undeeimalis 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 undeeimalis 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.


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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 3.2/oo to 15.0/oo. In 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.
E. evergladei 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 Utricularia 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. evergladei occurred primarily in stained, soft waters and was rare in clear, unstained, hard waters. In the study area, E. evergladei 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 Bohlke and Rohde (1980).
CENTRARCHIDAE sunFishes
51. Elassoma evergladei Jordan Everglades pygmy sunfish (I) VS 2, 4,10,15, 30, 31, 35
Figure 36


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Figure 36.- Distribution of Elassoma evergladei and Enneacanthus gloriosus in fresh water in southern Florida. 1 = Tabb and Manning (1961).


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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. Recent studies have investigated aspects of the reproductive behavior of E. evergladei (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 evergladei. 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 numbers 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).


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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 macrochirus) 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 (Micropterus 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. gulosus to be practically restricted to fresh water, never having collected it in salinities above 1.8/oo. We collected specimens at a salinity of 12.5/oo, 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


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Figure 37.-
- Distribution of Lepomis gulosus in fresh water in southern Florida.


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Figure 38.- Distribution of Lepomis macrochirus in fresh water in southern Florida. Open symbols signify sight records. 1 = Odum (1974).


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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. macrochirus 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 Erimyzon 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. purpurescens, 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 of 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. marginatus 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


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Figure 39.- Distribution of Lepomis marginatus in fresh water in southern Florida. Open symbols signify sight records.


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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. marginatus 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 (Giinther) 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. macrochirus 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 (Scirpus 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.


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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).


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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 11.0/oo.
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. punctatus 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. punctatus 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 12.5/oo salinity. Kilby (1955) reported a salinty range of 0.0/oo to 11.8/oo along the Florida Gulf coast, but Brockman (1974) found no L. punctatus in salinities exceeding 4.9/oo 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. punctatus 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. punctatus 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


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Figure 41.- Distribution of Lepomis punctatus in fresh water in southern Florida. Open symbols signify sight records.


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