| Session IV: Wetlands |
Abstract #: 97404 |
EVALUATING THE ROLE OF PHOSPHORUS AS A MECHANISM TO INDUCE ECOSYSTEM STATE CHANGE IN FRESHWATER WETLANDS OF EVERGLADES NATIONAL PARK:
SHORT-TERM RESULTS AFTER ONE YEAR OF ENRICHMENT
Daoust, Robert J., Childers, Daniel L., and Diana L. Rodriguez
Department of Biological Sciences, Florida International University, University Park, Miami, FL 33199
ABSTRACT
The Florida Everglades not only constitute one of North America's largest expanses of contiguous wetlands, but are also among one of its most imperiled ecosystems. Specifically, they have been divided up into three distinct regions: the Everglades Agricultural Area, a drained region used primarily for sugarcane production; the Water Conservation Areas, a large region managed by the State of Florida for water control purposes; and, Everglades National Park (ENP), the only region where conservation and protection of this unique ecosystem is given top priority. Anthropogenic activity in south Florida has altered both the natural hydrologic regime and the nutritional status of these wetlands. Past research has indicated that these changes affect natural Everglades wetlands, but are unclear as to whether one factor plays a greater causal role than the other. Since March 1996, we have been performing a nutrient enrichment experiment, using in situ mesocosms and two enrichment levels, in ENP to further evaluate the causal role that phosphorus enrichment plays in altering community structure and inducing ecosystem state change. Locating our experiment in ENP allowed us to eliminate the confounding effect of altered hydrologic regime since this area has been less impacted than others. Our analysis suggests that emergent macrophyte community composition remains unaffected. Those ecosystem components which cycle phosphorus more rapidly, such as soil and algal microbial processes, have, however, begun to be affected by our enrichment experiment. This suggests to us that phosphorus does play a role in causing the observed ecosystem state changes occurring in freshwater Everglades wetlands.
