Everglades Isotope Data

Data are available for the following sites: Cell 4, ENR-OUT, L7, Cell 3, LOX, North Holeyland, E0, F1, U3/Glory Hole, L35B, 2BS, L67, 3A-15, 3A-TH, Lostmans Creek, North Prong Creek, TS-7, and TS-9 for the plants and animals found at each site.

A first step of the Everglades restoration efforts is "getting the water right". However, the underlying goal is actually to re-establish, as much as possible, the "pre-development" spatial and temporal distribution of ecosystems throughout the Everglades. Stable isotope compositions of dissolved nutrients, biota, and sediments provide critical information about current and historic ecosystem conditions in the Everglades, including temporal and spatial variations in contaminant sources, biogeochemical reactions in the water column and shallow subsurface, and trophic relations. Hence, the scientific focus of this project is to use stable isotope techniques to examine ecosystem responses (especially variations in foodweb base and trophic structure) to temporal and spatial variations in hydroperiod and contaminant loading for the entire freshwater Everglades. The major "long-term" objectives of this project have been to: (1) determine the stable C, N, and S isotopic compositions of Everglades biota, (2) use bulk and compound-specific isotopic ratios to determine relative trophic positions for major organisms, (3) examine the spatial and temporal changes in foodweb structures across the ecosystem, especially with respect to the effect of anthropogenically derived nutrients and contaminants from agricultural land uses on foodwebs, (4) evaluate the effectiveness of isotopic techniques vs. gut content analysis for determining trophic relations in the Everglades, (5) evaluate the role of algae vs. detritus/microbial materials in foodwebs for the entire freshwater marsh part of the Everglades, and (6) work with modelers to correctly incorporate food web and MeHg bioaccumulation information into predictive models. We have generally completed the sample analysis parts of objectives #1-5, and are writing interpretative reports on topics #1-5. More recent and specific objectives include: (1) link our data on seasonal and temporal differences in foodweb bases and trophic levels with SFWMD, FGFFC, and USGS Hg datasets (first for large fish and, more recently, for lower trophic levels), (2) investigate the effects of seasonal/spatial changes in nutrients, water levels, and reactions on the isotopic compositions at the base of the foodweb (that affect our interpretation of relative trophic positions of organisms), and (3) continue our efforts to link our foodweb isotope data from samples collected at USGS-ACME and EPA-REMAP sites with the spatial environmental patterns observed by the REMAP program.

This work started as part of the Aquatic Cycling of Mercury in the E verglades (ACME) project in 1996 and was made a separate project in 2000.