David P. Green^1,2, William F. Loftus¹ and Carole C. McIvor^3
1U.S. Geological Survey, Florida Integrated Science Center, Homestead, FL, USA
²Audubon of Florida, Tavernier Science Center, Tavernier, FL, USA
³U.S. Geological Survey, Florida Integrated Science Center, Coastal and Watershed Studies, St. Petersburg, FL, USA

South Florida is currently the focus of major restoration efforts. Although food web and community-structure data have been collected in Everglades graminoid marshes, similar information from most other major south Florida ecosystems is limited. The fringing mangroves of Shark River, Everglades National Park, and the freshwater cypress domes in Big Cypress National Preserve provide ideal locations for interpreting the trophic patterns of fish and invertebrate communities in the forested wetlands of southern Florida. We are conducting baseline food-web studies in mangrove forested wetlands along the Shark/Harney rivers, and in the freshwater cypress swamps of the Big Cypress National Preserve. In conjunction with related Everglades studies, this study will contribute to a more comprehensive and integrated view of food webs across the natural landscape of south Florida.

Stable-isotope analyses of carbon (¹³C) and nitrogen (¹⁵N) are powerful techniques for interpreting pathways of energy flow in food webs and the trophic positions of higher consumers. We are characterizing primary producers (primarily vascular plants and benthic microalgae) at the base of mangrove and cypress food webs. When possible, we attempt to collect consumer groups common to both types of forested wetlands to enable comparisons between them (e.g., grazing amphipods, herbivorous snails, and carnivorous fishes). We continue to collect samples for analysis three times annually from the mangrove and cypress systems.

Here, we present preliminary stable-isotope data collected in 2005. Preliminary data show that detrital pathways are important in the forested wetlands. Data collected from the cypress system indicate that animals are likely moving from shallow, seasonally flooded prairies into the deeper cypress forests during dry seasons; further sampling will allow us to test this hypothesis. Our baseline characterizations of forested wetland food webs prior to restoration actions will enable examination of shifts in trophic structure in the mangrove and cypress systems resulting from those activities. Similarly, our food-web analyses will aid in the overall understanding of aquatic-community structure and trophic processes in these ecosystems.

Contact Information: David P. Green, Audubon of Florida, Tavernier Science Center, 115 Indian Mound Trail, Tavernier, FL 33070, USA, Phone: 305-852-5318, Fax: 305-852-8012, Email: dgreen@audubon.org

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

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