Abstract: At first glance the sawgrass prairie wetlands that make up a large part of the Everglades ecosystem in south Florida appear uniform across the landscape. From the air, except for the interspersed hardwood hammocks and the obvious vegetational differences along entrenched waterways, the sawgrass appears homogeneous and unchanging. This ecosystem, however, is extremely heterogeneous. This is due to the presence of micro-habitats that vary both spatially (horizontally and vertically) and over time (seasonally and longer). The forces that drive this heterogeniety include obvious, dominant physiographic characteristics such as climate, topography, and underlying geology. They also include less obvious, subtle forces such as wet-dry cycles, organic matter accumulation, trace element mobilization and transport, and the influence of human activities. These forces govern the dynamic chemical, physical, and biological processes that define the sawgrass ecosystem. An important concept to understand is that this ecosystem is highly variable and by understanding the magnitude of the variability we are better able to define the critical processes that drive the ecosystem. Agricultural practices and the management of surface water flow, occuring in and near the Everglades Agricultural Area (EAA) south of Lake Okeechobee, are important contributing factors in observed recent changes in the sawgrass prairie. The flow of waters enriched in nutrients is thought to play a role in mercury accumulation and cycling and in changes in vegetation communities (especially changes in algal populations and an increase in cattail and the decrease in sawgrass). It is believed that a variability gradient in this influence occurs primarily from north to south; however, the relative importance of surface vs. ground water flow patterns, and the associated hydro-geochemistry, has not been defined.
Purpose: The Role of Peat in the Ecosystem: An important driving force in the sawgrass ecosystem of south Florida is the role of accumulated organic matter (peat), and the sawgrass growing in it, on the cycling of trace elements (metals) and nutrients (e.g., nitrate and phosphate). Understanding the natural variability within a vertical column of peat helps us better understand the cause of sudden major changes that sometimes create an environmental crisis. For example, the discovery of high levels of the toxic metal mercury in panther, fish, and alligator signal a shift in some ecosystem process(es) that lead to the metal's uptake and "biomagnification". But when did this shift occur, what was the cause(s) of the shift, and what role does the peat have in mercury cycling?
Supplemental Information: This project was part of the Aquatic Cycling of Mercury in the Everglades (ACME) project which has become the Integrated Geochemical Studies in the Everglades

Progress: Complete
Update Frequency: None planned

Theme Keywords: none, mercury, biogeochemistry, mercury cycling, peat, sawgrass, trace elements, biology, hydrology, chemistry, ISO 19115 Topic Category, biota, environment, geoscientificInformation, inlandWaters, imageryBaseMapsEarthCover, 002, 007, 008, 012, 010
Place Keywords: United States, US, Florida, FL, Collier County, Broward County, Miami-Dade County, Monroe County, Palm Beach County, Shark River Slough, Taylor Slough, Lake Okeechobee, Central Everglades, Greater Lake Okeechobee, SW Big Cypress

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