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Project Summary Sheet

U.S. Geological Survey, Greater Everglades Science Program: Place-Based Studies

Fiscal Year 2002 Project Summary Sheet

Project: Mercury Transfer Through an Everglades Aquatic Food Web

Web Sites: (see;

Location (Subregions & Counties): Central Everglades; Miami-Dade

Funding (Source): Florida Dept. Environmental Protection funding to FIU; Base funding to USGS-BRD, Florida Caribbean Science Center

Principal Investigator(s): William F. Loftus, 305.242.7835,; Joel Trexler, 305.348.1966,; Ronald Jones, 305.348.3095,

Project Personnel:

Supporting Organizations: Collecting permits - NPS and FFWCC. Mesocosm at ENP was used

Associated / Linked Projects: ATLSS (USGS study); Everglades Restudy (RECOVER); EPA REMAP, and USGS-ACME

Overview & Status: This study has been completed. The goal of this study was to identify the important routes and processes by which mercury is passed to the top trophic levels in the Everglades system. There were three study objectives. The first described the food habits and trophic positions of Everglades marsh fishes, and the changes in diet associated with seasonal water-level fluctuations. The dietary patterns for the Everglades community were compared with data for tropical wetlands from the literature. The data were used to construct a food web leading to the fishes. The second segment correlated total mercury concentrations in Everglades fishes and invertebrates to their trophic positions to test for bioaccumulation. The third segment examined the effects of time-of-year and site hydroperiod on mercury levels of wild and caged mosquitofish at three pairs of locations. This project is completed and manuscripts are in preparation for journal submission.

Needs & Products: 1) Loftus, W. F., J. C. Trexler, and R. D. Jones. 1998. Mercury Transfer Through an Everglades Aquatic Food Web. Final report to Florida Dept. of Environmental Protection, Tallahassee; 2) Loftus, W.F. 2000. Accumulation and fate of mercury in an Everglades aquatic food web. Ph.D. Dissertation, FIU, Miami, FL; 3) Arrington, D. A., K. O. Winemiller, W. F. Loftus, and S. Akin. In Press. How often do fishes "run on empty"? Ecology; 4) Several posters and presentations at meetings; other papers in preparation.

Application to Everglades Restoration: These data, combined with landscape-level studies of mercury geochemistry and patterns of concentrations in biota, will be useful as Performance Measures in RECOVER. The results were used in Phase 1 of the South Florida Mercury Program, in the development of the EPA BASS model of bioaccumulation, and in comparison with other studies in the Everglades. 

Study Milestones
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Familiarity xx                    
Design xx xxxx                  
Field Work xx xxxx xxxx                
Data Analysis xx xxxx xxxx xxxx xxx            
Initial Reporting   xxxx xxxx xxxx              
Quality Assurance xx xxxx xxxx xxxx x xx          
Results Published     x x   x   o o    
Synthesis               o      
Note: "x" indicates task completed during quarter, and "o" indicates task planned, but not completed

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