THE USE OF OSTRACODES AS BIOINDICATORS OF ANTHROPOGENIC CONTAMINANTS IN WETLANDS IN LAKE ERIE BASIN, NORTHEASTERN OHIO

As heavy metal contamination becomes a growing problem in industrialized areas, determining levels of toxicity in water, sediment and biota becomes increasingly important. There have been attempts to devise proxy indicators for evaluating environmental contamination over the past forty years. Despite this, questions remain about the best way to monitor heavy metal pollution and its remediation. This study examines if the microcrustacean group Ostracoda can be used as proxy indicators in this context. Water, sediment and ostracodes were sampled from three wetland sites of increasing impact in the Lake Erie watershed: low impact (Old Woman Creek), moderate impact (Mentor Marsh) and high impact (Fields Brook). All samples were analyzed for heavy metals using ICP-MS and compared for intersite and intrasite variability. Within each site, water always appeared to have the lowest values, while the ostracode valves almost always had the highest. Between sites, the low impact site (OWC) typically had the lowest values of heavy metals and the high impact site (FB) had the highest. In addition, there was little intrasite variability within the low and moderately impacted sites, but the highly impacted site showed disparity between the values. Our study indicates there may be bioamplification of available metals in these organisms and suggests that the minimum toxicity levels as established for water and sediment should also be established for biota. The high levels of heavy metals within Fields Brook, a remediated Superfund site, indicates that remediation was not as effective as projected and should be evaluated for additional clean-up.