Historical Changes in Water Quality and Vegetation in WCA-2A Determined by Paleoecological Analyses

The objective of the paleoecological study discussed in this chapter is to determine historical changes in water quality (and quantity) and vegetation types over the past 100–500 years in relation to human-induced changes to the hydrology and nutrient inputs of the Everglades using paleoecological analyses of soil cores from WCA-2A. Samples have been analyzed for diatoms, pollen, total phosphorus (P), percent nitrogen (% N), percent organic carbon (% C), calcium and sodium ions (Ca and Na, respectively), and biogenic silica (BSi). These geochemical parameters provide an indication of loading of these elements to the system at different sites, as well as preservation of these elements within the soils. Concentrations of P, % N, and % C reflect both nutrient inputs and productivity within the system. BSi is primarily a measure of diatom production, but also includes chrysophyte cysts and sponge spicules, all of which are composed of amorphous silica. Biogenic silica can be measured separately from mineral silica (Conley 1988).