Abstract

Monitoring of benthic invertebrate communities in aquatic ecosystems has been used to evaluate a variety of environmental effects, including changes in hydrology. As part of a hydroecological assessment of the St. Johns River, FL, we studied invertebrate communities of shoreline and floodplain marsh habitats at locations in the middle and upper St. Johns River. A total of 112 invertebrate taxa were identified. Most were aquatic insects in the orders Odonata, Hemiptera, Coleoptera and Diptera. We examined a variety of metrics of invertebrate community structure and a surrogate measure of ecosystem function. Some of these metrics displayed patterns that could be related to hydrology. Preliminary sampling in floodplain marsh habitats with varying duration of inundation suggested some hydroecological patterns; relative abundance of taxa indicative of more permanent aquatic habitats (Ephemeroptera and Amphipoda) had a positive relationship with duration of inundation. Taxa able to undergo diapause during dry periods (Oligochaeta), those able to disperse to new habitats (Diptera, Coleoptera), and those with short life cycles adapted to temporary habitats (Diptera) had negative relationships between relative abundance and duration of inundation. We propose three new metrics that may be useful for future monitoring.