Shawn E. Liston¹, Bradley E. Dunker¹, David P. Green^1,2, William F. Loftus² and Jerome J. Lorenz^1
1Audubon of Florida, Tavernier Science Center, Tavernier, FL, USA
²U.S. Geological Survey, Florida Integrated Science Center, Everglades National Park Field Station, Homestead, FL, USA

Freshwater forested-wetland habitat may be critical for many fish and macroinvertebrate communities. Trees provide habitat structure (particularly, above-ground root systems, trunks with complex surfaces, and woody debris) that is invaluable as cover, spawning, and feeding sites for resident species. Annual water-level fluctuations may help drive intra- and inter-specific competition for food, space, and spawning sites in fish communities. Furthermore, because seasonally flooded forests become isolated from continuously inundated areas as water levels recede, competition for food in these systems and vulnerability to predators may become increasingly important for aquatic animals as the dry season progresses. The Big Cypress Swamp ecosystem encompasses a large area of interior southwestern Florida. Although the Swamp is an important part of the regional hydrologic system of the greater Everglades, its ecology has been poorly studied compared to Everglades graminoid wetlands. As part of the Comprehensive Everglades Restoration Program (CERP) Monitoring and Assessment Plan (MAP), we are testing a variety of sampling methods for fishes and macroinvertebrates in forested wetlands to describe variation in fish and macroinvertebrate community structure and density at various spatial scales. We are sampling aquatic animals in three regions of Big Cypress National Preserve: Bear Island, Raccoon Point, and an area near the L-28 Interceptor Canal to provide baseline data on communities prior to the initiation of restoration activities. At each site, we use 9-m² drop traps and 1-m² throw traps in shallow, seasonally inundated forests and deeper, continuously inundated forests. We also used throw traps in surrounding cypress prairies. This design allows us to define seasonal movements among those major habitats. Sampling was conducted five times between July 2005 and April 2006, and is ongoing.

Thus far, we have found significant variation in fish-community structure and density between shallow- and deeper-water forests, and significant inter-annual variation in those patterns. Macroinvertebrate biomass also varied significantly within each site and inter-annually. The proportion of predatory fish and macroinvertebrates was extremely high in both shallow and deep forests, and appeared to increase as the dry season progressed. Omnivorous fishes were common in cypress prairies during high water. Our data suggest aquatic animals may utilize shallow habitats surrounding forested wetlands in the wet season, moving into forests in the dry season as water levels recede. Ponds in the forests appear to provide important refuge habitat for fishes throughout the dry season. Because the scientific literature contains little information about the ecology of aquatic animals in cypress forests, our study is providing valuable data not only for CERP, but for comparison with other cypress systems in the southeastern United States.

Contact Information: Shawn E. Liston, Audubon of Florida, Tavernier Science Center, 115 Indian Mound Trail, Tavernier, FL 33070 USA, Phone: 305-242-7842, Fax: 305-242-7836, Email: shawn_liston@usgs.gov

(This abstract is from the 2006 Greater Everglades Ecosystem Restoration Conference.)

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