LIVE/DEAD ANALYSIS OF MOLLUSCAN COMMUNITIES IN IMPACTED TEMPERATE LACUSTRINE ECOSYSTEMS: HIGH FIDELITY IN REMEDIATED LAKES AND EVIDENCE OF ANTHROPOGENIC IMPACT

Anthropogenic impacts, including eutrophication, overfishing, and pollutants, cause degradation of lacustrine ecosystems. Understanding and providing a historic record of these impacts and their affect on aquatic communities is essential for conservation. Comparison of living assemblages with death assemblages is one way to quantify the history of human impact. The fidelity of living and death assemblages is high in a variety of pristine environments and much lower in impacted environments, but live/dead comparisons specific to temperate freshwater lakes remain undone. To address this knowledge gap, we quantified the differences in species richness, community evenness, rank order, and taxonomic similarity for living and death assemblages of mollusks collected as grab samples from four lakes in Wisconsin: two remediated and two impacted. Samples from the impacted lakes have the lowest species richness, are the most uneven, and have the lowest live/dead agreement. Despite the ephemeral nature of the live samples, live/dead agreement in samples from the remediated lakes is generally good, with results similar to those of live/dead comparisons completed with ostrocods found in undisturbed, tropical lakes. Our preliminary results suggest that live/dead comparisons of molluscan assemblages from lacustrine environments provide a useful measure of anthropogenic impact, and that these assemblages may provide a historical record when collected from cores. Additionally, results suggest that remediation attempts are successful in maintaining molluscan communities. However, sampling pristine lakes can augment our analysis of the gradient of human impact, and collection of cores can provide a more meaningful historic baseline from which to measure human impact.