Response of macroinvertebrates and small fish to nutrient enrichment in the northern Everglades

摘要: The northern Everglades (Water Conservation Area 2A) annually receives an excess addition of 60M tons phosphorus and 1814 M nitrogen from agricultural run-off. During 1990–91, invertebrates were collected replicate sweep core samples at eight sites along the nutrient enrichment gradient in Water 2A (WCA-2A). Species richness, Shannon’s diversity, number unique species, density small fish all greater within enriched intermediately open water habitats than unenriched sloughs. Sorenson’s taxonomic similarity index was significantly different between areas. Ostracods particular 14 times more abundant area sites. freshwater shrimp (Palaemonetes paludosus) only common species with lower densities However, trophic structure or percent composition grazers, predators, collector-gatherers orders functional feeding groups very similar among gradient. Higher invertebrate diversity indicates that has not caused direct harmful foodweb effects may adversely influence higher levels (e.g., wading birds). Assuming, however, nutrients can cause cattails to overgrow eliminate sloughs, centers biological Everglades, then have indirect effects.