Inventory of Freshwater Fish Species Within Big Cypress National Preserve: the Basis for a Long-Term Sampling Program

Inventory of Freshwater Fish Species within Big Cypress National Preserve: The Basis for a Long-Term Sampling Program

Introduction habitats because fishes were concentrating, but had not yet experienced high mortality. We emphasized sampling during The Big Cypress ecosystem forms a largely undeveloped this period to record the maximum number of species living landscape in southwestern Florida. The ecosystem includes within each habitat. In addition, shallow wetlands were three major habitats: seasonally flooded marshes, forested sampled during the summer and fall high-water period. wetlands and upland pine habitats, all of which are intersected Because much of BCNP is inaccessible by road, helicopter, by manmade canals. Much of the landscape lies within the swamp buggy, and all-terrain vehicles were used to reach Federally protected Big Cypress National Preserve (BCNP), interior sites within the Preserve. which is managed by the National Park Service (fig. 1). To The diversity of habitats in BCNP presented challenges to understand this ecosystem, knowledge about the ecology of its the development of a comprehensive sampling regime. The fishes is especially important, because they are the most numer- effectiveness of any method varies by habitat, and each has ous vertebrates within the Preserve, and provide food for preda- inherent biases. To compensate, we used several techniques tors such as wading birds and alligators. The hydrologic change when taking a sample. Traps and nets provided a means of resulting from surface-water drainage and impoundment within the system has probably decreased fish biomass and numbers, Number of and altered the timing and the areas of fish availability to preda- Habitat samples tors (Duever and others, 1986). In addition, non-native fish Canals 155 species have colonized natural and disturbed habitats of the Big Cypress forest 49 Cypress ecosystem during the past three decades, because the Freshwater marsh 42 Table 1. Number of local climate and habitats are favorable for their colonization and Herbaceous prairie 33 samples per habitat type survival (Loftus and Kushlan, 1987). Sloughs/ponds/rivers 25 Only recent baseline data exist for fish communities in the Cypress prairie 15 Big Cypress system, and these data are relatively scarce. The first collections were made in the 1960s and 1970s during Mixed swamp forest 14 studies of the prey populations for wading birds (Kahl, 1964; Coastal marshes 10

Browder, 1976; Kushlan, 1974). The composition and distribu- 83° 82° 81° 80° tion of native and introduced fishes from the southern areas of ST. LUCIE SARASOTA DE SOTO HIGHLANDS the Preserve were reported on by Loftus and Kushlan (1987). EXPLANATION MARTIN 27° Big Cypress National Preserve Lake OKEECHOBEE Limited collections were made by W.F. Loftus (National Park Everglades National Park Okeechobee CHARLOTTE GLADES PALM BEACH Service, written commun., 1987), and by Dalrymple (1995). Direction of surface-water flow Road Small quantitative datasets on fish communities exist only for LEE HENDRY Canal HISTORIC Corkscrew Swamp (Carlson and Duever, 1977), and coastal S-190 Control Structure EVERGLADES habitats in the southern Big Cypress Swamp (Carter and others, COLLIER PALM BEACH COUNTY BROWARD COUNTY HENDRY COUNTY COLLIER COUNTY 1973). The present study, funded by the USGS Greater Ever- Gulf of Mexico BROWARD Naples glades Priority Ecosystems Science Program, in cooperation 26° BROWARD CO

with BCNP, was conducted to produce a complete inventory of Atlantic Ocean MIAMI-DADE

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Tu S-344 from October 2002 through June 2004 (Ellis and others, 2003). 25° Birdon Road Road L28 41 11 Mile We collected multiple samples in all major aquatic habitats in Levee Loop S-12A the Preserve. We also took samples during several seasons at Road S-343A 0 25 50 MILES many locations (table 1). Most data, however, were collected 0 10 MILES S-343B during the winter/spring dry season in canals and other deep- 0 10 KILOMETERS 0 25 50 KILOMETERS water habitats. The transition between the wet and dry seasons coincided with the time of highest species richness in many Figure 1. Map showing Big Cypress National Preserve.

U.S. Department of the Interior Fact Sheet 2004-3131 U.S. Geological Survey Printed on recycled paper November 2004 sampling with a standardized unit of effort (soak time), Table 2. Distribution of fish species by habitat and were suitable for most habitats. We used Gee-type minnow traps, box traps, collapsible mesh traps, and Breder traps. Soak times were generally 24 hours, although 1-hour sets were also performed. Small-fish Species traps were fished unbaited and relied on encounter by the fish to generate captures. Hoop nets were normally Canals Sloughs, ponds, rivers Mixed swamp forest Freshwater marsh Cypress forest Cypress prairie Herbaceous prairie Coastal marshes All wetlands Freshwater wetlands Deep-water habitats fished unbaited, but were baited for 24-hour periods American eel x x ------x in deep-water areas to sample larger fishes. We used Atlantic needlefish x ------x experimental gill nets to sample canal fishes by deploy- black acara x x x x x x x x x x - ing two nets in tandem, each with four 2.4-meter deep black crappie x ------x x 1.8-meter wide panels. The first net had panels with blue tilapia x x - x x x - x x x - bar-mesh sizes of 1.2, 2.5, 3.7, and 5 centimeters, and bluefin killifish x x x x x x x x x x - the second had meshes of 6.2, 7.6, 8.8, and 11 centime- bluegill x x x x x - - x x x - ters. Nets were typically set from 1 to 4 hours. bluespotted sunfish x x x x x - x x x x - We employed two electrofishing rigs to sample bowfin x x - - x - - - x x - fishes. The first was a boat-mounted Smith-Root type brook silverside x x - x x x x - x x - 6A electrofisher with a maximum current output of brown bullhead x ------x 1,008 volts dc at 120 pulses per second. It performed brown hoplo x ------x well in sampling canals, but was too large for use in clown goby x ------x x - - vegetated habitats. In forested habitats and marshes, coastal shiner x ------x crested goby x ------x we sampled with a small barge carrying a Smith-Root crevalle jack x ------x model 2.5 Gas-powered Pulsator (GPP) electrofisher dollar sunfish x x x x x x x x x x - having a maximum current of 1,000 volts dc at Everglades pygmy x x x x x - x - x x - 120 pulses per second. Samples were standardized to sunfish 300 seconds of total shock time. flagfish x x x x x x x x x x - We also maintained sight records for species Florida gar x x x x x x x - x x - observed but not captured, which we were able to frillfin goby x ------x gizzard shad x ------x positively identify. Extensive collections of voucher golden shiner x x x x - - - - x x - specimens were saved to document the identities of golden topminnow x x x x x x x x x x - BCNP fishes, and they are stored at the South Florida gray snapper x ------x Collection Management Center repository at Everglades gulf killifish x ------x x - - National Park. hardhead catfish x ------x Habitat Classification hogchoker x x - - - - - x x - - inland silverside x ------x x - - Sampling was planned using a stratified design based jewel cichlid x - - x - - x - x x - on habitat category. The habitat-classification scheme ladyfish x ------x was based on the seasonally inundated habitats identi- lake chubsucker x x - - x - - - x x - fied by Duever and others (1986). Eight broad habitat largemouth bass x x x x x x x x x x - categories were used, based on dominant vegetation least killifish x x x x x x x - x x - marsh killifish x x x x x x x x x x - and hydroperiod (National Park Service, 1991); six of Mayan cichlid x x x x x x x x x x - these are subject to seasonal dry-down. The habitats are mosquitofish, eastern x x x x x x x x x x - ranked by hydroperiod from longest to shortest: oscar x x - - - - x - x x - • Cypress forest — includes bald cypresscypress Taxodium pike killifish x x x x x x x x x x - distichum and pond cypress Taxodium ascendens. pinfish x ------x • Mixed swamp forest — forested wetlands domi- rainwater killifish x x - - - - - x x - - nated by hardwoods (Duever and others, 1986). red drum x ------x redear x x x x x x - x x x - • Freshwater marshes — wetlands dominated by a redfin needlefish x ------x variety of grasses and sedges. redfin pickerel - - - - x - - - x x - • Coastal marshes — herbaceous wetlands that sea- sailfin molly x x x x x x x x x x - sonally vary between fresh and brackish salinities Seminole killifish x x - x - - - - x x - sharksucker x ------x (National Park Service, 1991). sheepshead x ------x • Cypress prairie — wetland with an open canopy of sheepshead minnow x - - x - - x x x x - sparse dwarf pond cypress (National Park Service, snook x x ------x 1991). spotted sunfish x x x x x x x - x x - • Herbaceous prairie — short-hydroperiod wetlands spotted tilapia x x x x x x x x x x - characterized by a variety of grasses (Duever and striped mojarra x x ------x others, 1986). striped mullet x x - - - - - x x - - swamp darter x ------x Table 2. Distribution of fish species by habitat—Continued littorale), and the clariid walking catfish (Clarias batrachus). This study is the first to document Hemichromis and Hoplosternum from the Preserve, both of which are expanding their ranges southeast- Species ward (fig. 2). The number of non-indigenous species in BCNP has grown from three in the late 1970s (Loftus and Kushlan, 1987) to nine in 2004. Additional Canals Sloughs, ponds, rivers Mixed swamp forest Freshwater marsh Cypress forest Cypress prairie Herbaceous prairie Coastal marshes All wetlands Freshwater wetlands Deep-water habitats non-native species are present in the canal system near tadpole madtom - - x - - - - - x x - BCNP boundaries, which supports the hypothesis that taillight shiner x ------x this trend will continue. The Mayan cichlid is an exam- tarpon x x ------x tidewater mojarra x ------x ple of a successful non-indigenous fish that has spread timucu x ------x throughout much of the Preserve, where its population walking catfish x x x - - - - x x x - is especially large in canals. The potential ecological warmouth x x x x x x x x x x - consequences of these invasions are uncertain. yellow bullhead x x - x x - x - x x - The freshwater marshes and forested wetlands Two additional habitats hold water year-round: shared similar fish assemblages. Of the 33 species • Canals — deep-water refuges for fishes during the dry found in these habitats, 16 were common to all. Small season, from which they disperse in the wet season. fishes utilized shallow-water areas such as herbaceous • Sloughs/ponds/rivers — natural, persistent water bod- prairies and cypress prairies when those habitats were ies. Ponds and rivers comprise a small geographic area inundated. As the shallow habitats dried, the relative of BCNP, but include important features as such as Deep abundance of those fishes in nearby swamp forests and Lake, Mud Lake, and Turner River. cypress strands appeared to increase. This pattern was reported by Carlson and Duever (1977) for flagfish Results and Discussion (Jordanella floridae) and least killifish (Heterandria formosa) populations during the annual dry-down of From our sampling efforts, we identified 64 fish species Corkscrew Swamp, and also occurs in the Everglades (table 2). Fifty-five species are native to North America, and wetlands (Loftus and Kushlan, 1987). Small-bodied include species-rich groups such as sunfishes (Centrarchidae), species, such as the eastern mosquitofish (Gambusia killifishes (Cyprinodontidae and Fundulidae), livebearers holbrooki), were often the most ubiquitous and (Poeciliidae), and catfishes (Ictaluridae). We also recorded nine numerous fishes in the samples (fig. 3). nonindigenous species, most of which are in the cichlid family: Canals held the most diverse assemblage of fishes; Oscar (AstronotusAstronotus ocellatus), black acara (Cichlasoma bimacu- 62 of the 64 species documented in the Preserve latum), Mayan Cichlid (Cichlasoma urophthalmus), blue tilapia occurred within this habitat. Although this relatively (Oreochromis aureus), spotted tilapia (Tilapia mariae), and high species richness reflects a greater sampling effort Jewel Cichlid (Hemichromis letourneauxi). Three non-cichlids in this habitat compared to other habitats (table 1), it were recorded: the poeciliid pike killifish (Belonesox belizanus), also is related to the presence of fish species that the callichthyid brown hoplo catfish (Hoplosternum

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0 10 KILOMETERS 0 10 KILOMETERS

Figure 2. Newly established, introduced fishes in Big Cypress National Preserve include the Brown Hoplo catfish (Hoplosternum littorale) and Figure 3. Distribution of the eastern mosquitofish, Gambusia holbrooki, Jewel Cichlid (Hemichromis letourneauxi). Copyrighted image used was ubiquitous in Big Cypress National Preserve fish samples. with permission. typically inhabit deep, open-water habitats, and to marine fishes Continuing Research that tolerate a wide range of salinities (“euryhaline” species). This inventory is the initial step in a fish research program Open-water species included the brown bullhead (Ameiurus for BCNP. Although we identified effective methods for nebulosus), gizzard shad (Dorosoma cepedianum), redear sampling various habitats during the inventory, the sampling (Lepomis microlophus), and black crappie (Pomoxis nigromacu- did not include quantitative measurements of population latus), which are rarely found in BCNP wetlands. The marine densities. Quantitative data describing fish-community invaders penetrate inland from the Gulf of Mexico through dynamics in the Big Cypress Swamp are lacking, except for coastal canals. They do not seem to enter wetland habitats short-term studies in the Corkscrew Swamp (Carlson and other than by way of channels in coastal marshes. Species in Duever, 1977) and southern Big Cypress region (Carter and this category include the various needlefishes (Strongylura others, 1973). We have begun a long-term program to study spp.), mojarras (Eugerres and Eucinostomus), and gobies community composition and dynamics before and after resto- (Bathygobius, Lophogobius and Microgobius), as well as snook ration actions change hydrologic patterns in the region. Our (Centropomus undecimalis), gray snapper (Lutjanus griseus) current work includes repetitive sampling five times per year to and tarpon (Megalops atlanticus). The diversity and numbers compare baseline community data at sites within areas likely to of non-indigenous fishes are high in canals, especially during be affected by hydrologic changes with those that will experi- the dry season. Coastal marshes are also used by euryhaline ence little effect. We are using equipment that provides density species, and during the wet season, support most of the fresh- estimates for fishes in forested wetlands, especially quadrat water species found in the Preserve. Euryhaline species present drop traps. Sites are also sampled with drift-fence/minnow- in this habitat include clown goby (Microgobius gulosus), gulf trap arrays, with electrofishing, or other nets. Results from killifish (Fundulus grandis), rainwater killifish (Lucania parva), these quantitative collection efforts will help us better under- and striped mullet (Mugil cephalus). stand the functioning of the fish community in this large, Sloughs, ponds, and rivers are the only natural habitats complex ecosystem. that retain water year-round. Few rivers exist within BCNP, although Turner River drains its southwestern portion. Lakes References Cited are also uncommon within BCNP; however, constructed borrow pits function as lakes. Both habitats, particularly those with Browder, J.A., 1976, Water, wetlands, and wood storks in southwest Florida: Gainesville, University of Florida, Ph.D. dissertation, 406 p. hydrologic connections to the canal system, are home to large Carlson, J.E., and Duever, M.J., 1977, Seasonal fish population fluctua- euryhaline and freshwater species. An example is the populations in a South Florida swamp, in Proceedings of the Southeastern tion of tarpon and Florida gar inhabiting Deep Lake—a flooded Association of Fish and Wildlife Agencies, v. 31, p. 603-611. sinkhole adjacent to the Barron Collier Canal. Carter, M.R., Burns, L.A, Cavender, T.E., and others, 1973, Ecosys- Loftus and Kushlan (1987) reported 34 native and 3 non- tems analysis of the Big Cypress Swamp and estuaries: U.S. Envi- indigenous species from their collection efforts, compared to ronmental Protection Agency, Region IV: Atlanta, Georgia, U.S. 56 native and 9 non-native species in the present study. How- Environmental Protection Agency Report 904/9-74-002. ever, a similar number of species were collected from the fresh- Dalrymple, G.H., 1995, Wildlife Inventory for Baseline Studies of the Addition Lands of the Big Cypress National Preserve: Miami, water wetlands in both studies (29 in the earlier study and 33 in Report prepared for Florida International University. this study). The increase in species in the present study Duever, M.R., Carlson, J.E., Meeder, J.F., and others, 1986, The Big is the result of much greater sampling effort, particularly in Cypress National Preserve: New York, National Audubon Society, coastal canals and rivers, and a larger sampling area. Loftus and 455 p. Kushlan (1987) sampled only the southern area of BCNP, which Ellis, G., Zokan, M., Lorenz, J., and Loftus, W.F., 2003, Inventory of lies south of U.S. Highway 41. Loftus and Kushlan (1987) the freshwater fishes of the Big Cypress National Preserve, with a found that species composition within the Big Cypress Ever- proposed plan for a long-term aquatic sampling program: Annual Project Report to the USGS Priority Ecosystems Science Program, glades ecosystems were nearly identical; our data support this Davie, Florida, 104 p. finding. Kahl, M.P., 1964, Food ecology of the wood stork (Mycteria ameri- Several previously reported species within the Preserve were cana) in Florida: Ecological Monographs, v. 34, p. 97-117. not collected in the present study. W.F. Loftus (National Park Kushlan, J.A., 1974, Effects of a natural fish kill on the water quality, Service, written commun., 1987) found diamond killifish (Adinia plankton, and fish population of a pond in the Big Cypress Swamp, xenica) and naked goby (Gobiosoma bosc). The survey by Florida: Transactions of the American Fisheries Society, v. 103, Dalrymple (1995) of the northern BCNP area included reports p. 348-352. of chain pickerel (Esox niger) and channel catfish (Ictalurus Loftus, W.F., and Kushlan, J.A., 1987, Freshwater fishes of southern Florida: Bulletin of the Florida State Museum, Biological Sciences, punctatus) in the L-28 Canal. None of these species appear to v. 31, p. 147-344. be widespread in BCNP. National Park Service, 1991, Big Cypress National Preserve General Management Plan and Final Environmental Impact Statement: Ochopee, Florida.

For further information contact:

William F. Loftus Greg Ellis, Marcus Zokan, and Jerome Lorenz U.S. Geological Survey National Audubon Society Florida Integrated Science Center Tavernier Science Center 40001 State Road 9336 Homestead, FL 33034 305-242-7835; 305-242-7836 (fax) E-mail: [email protected]