MIDGE COMMUNITY RESPONSE TO NUTRIENT ENRICHMENT IN EVERGLADES NATIONAL PARK.

R.E. Jacobsen and S.A. Perry. South Florida Natural Resources Center, Everglades National Park, Homestead, FL

Recent work on Everglades invertebrates by King and Richardson (JNABS 2002) indicated that chironomid communities showed strong compositional changes along a steep eutrophication gradient in the northern Everglades. Genus- or species-level taxonomic inquiries into midge communities were particularly informative and were recommended for detecting wetlands enrichment, despite the taxonomic effort required. Collecting surface-floating exuviae is a much more efficient method for obtaining species-level information on midge communities than collecting and identifying larvae using conventional methods. In our study, we used quantitative collections of midge (Chironomidae and Ceratopogonidae) pupal exuviae to measure: (a) midge community response to 3 levels of phosphorus enrichment (5, 15, and 30 ppb above ambient P-levels) in replicated, large-scale, P-dosing flume experiments conducted within Everglades National Park (ENP), and (b) midge community changes and their relationships to ambient water, soil, and plant-tissue nutrient levels in representative habitats along inflow plumes into ENP. In the P-dosing flumes, midge community richness and diversity showed no change with increasing enrichment. However, significant compositional changes were observed. Compositional changes observed along inflow gradients on the eastern border of ENP suggest water quality may be lower in marshes adjacent to these eastern-bordering canals than those south of the Tamiami Canal.