(White and Reddy, 2000), and other ecological changes have been observed in

Everglades areas receiving nutrient inputs from canal waters with TP concentrations as

much as 10-30 fold higher than background (McCormick et al., 1996).

 Field study sites were located in transects situated along nutrient gradients in four

distinct hydrologic units of the Everglades: Arthur R. Marshall Loxahatchee National

Wildlife Refuge (LNWR), Water Conservation Area 2A (WCA-2A), Water Conservation

Area 3A (WCA-3A), and Taylor Slough within Everglades National Park (ENP-TS).

 Loxahatchee National Wildlife Refuge (LNWR) is the northernmost of the

hydrologic areas in the Everglades, completely impounded by levees and canals, and

encompasses 566 km2. The phosphorus gradient in this area exhibits a steep decline with

surface water and soil TP levels decreasing to reference levels within 2.2 km of the L-7

canal (SFWMD, 2003). LNWR hydrology is primarily rainfall driven (54%) and is,

unlike the rest of the Everglades, an acidic soft water system. Sites were chosen on a

transect located along a nutrient gradient extending from the L-7 canal and represented

enriched (XI), transitional (X2), and reference (X4) P conditions which are designated as

the ENR, TRANS, and REF sites, respectively. The average surface water TP

concentrations were between 7.2 and 12.3 [ig L-1 between 1996 and 2001 for the

reference site (SFWMD, 2003).

 Water Conservation Area 2A is a 442 km2 area located in the northern

Everglades, completely enclosed by canals and levees, and is the most studied among the

regions. The primary source of water and nutrient loading to the area are the S-10

structures that transfer water from agricultural areas and LNWR via the Hillsboro Canal.

Nitrogen and phosphorus gradients exist in the water column and periphyton tissue