Benthic Invertebrate Communities of the Lake Okeechobee, Florida, Sublittoral Zone: 1987 to 2007
Gary L. Warren, Florida Fish and Wildlife Conservation Commission, 7922 NW 71^st Street, Gainesville, FL  32653
gary.warren@myfwc.com
Lake Okeechobee is one of North America’s largest and most economically important natural resources.  The ecological health of the lake has deteriorated since the 1970s in response to stabilized water levels and increased nutrient loading.  The Florida Fish and Wildlife Conservation Commission has sampled benthic invertebrate communities within the three major habitat zones of the lake’s sublittoral area since 1987 with the purpose of evaluating trophic status and health of the fish food resource.  Oligochaeta and Chironomidae have numerically dominated all sampled habitat zones since sampling was initiated in 1987; however, densities of many formerly abundant species (e.g.  Limnodrilus hoffmeisteri) have declined significantly, and some ecologically important species (e.g. Chironomus crassicaudatus and Viviparus georgianus) apparently have been extirpated.  Per sample means of taxa richness, diversity (Shannon’s equation), and total organisms have declined significantly.  Abundances of several fish species have declined concurrently with the reduction of invertebrate numbers.  Of the numerically dominant invertebrate taxa, only Corbicula fluminea has increased in abundance.  Eutrophication and poor habitat conditions resulting from three hurricanes in a two year period are implicated in the most recent declines in invertebrate community quality.