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(438) Effects of lawn care chemicals on oxidative stress in clams from streams during wet and dry seasons.
Conners, Deanna*,1, Armbrust, Kevin1, Shuman, Larry1, Black, Marsha1, 1 University of Georgia, Athens, GA, USA
ABSTRACT- Many chemicals, including fertilizers, herbicides, insecticides and fungicides, are routinely applied to turf in the care and maintenance of lawns, and have the potential to leach into nearby surface waters and adversely affect aquatic biota. Because oxidative stress is a common mechanism of toxicity by which diverse chemicals exert adverse effects, we evaluated biomarkers of oxidative stress (superoxide dismutase, catalase, glutathione, lipid peroxidation and DNA damage) and condition index in clams (Corbicula fluminea) that were exposed in-situ to suites of lawn care chemicals. Clams were deployed in 6 freshwater streams receiving residential lawn runoff for 4 and 8 weeks during a dry summer and a wet summer. We have observed that clams from contaminated sites exhibit transient signs of oxidative stress (i.e., elevated superoxide dismutase and catalase activity) at 4 weeks but not at 8 weeks and that condition indices worsen late in exposures. These data suggest that clams may be able to compensate for adverse cellular effects but the energy required for amelioration will eventually affect organismal health. Annually, we have observed that streams during wet seasons have higher contaminant concentrations, and that clams from these streams displayed biomarker response patterns and condition indices indicative of severe oxidative stress. From these data, we have developed a discriminant model that describes how biomarker responses can be linked to higher levels of biological organization, and illustrates how multivariate analyses can be used to evaluate the contribution of contaminants in the etiology of adverse effects in in-situ bioassays. In conclusion, this research highlights the sensitivity and utility of the use of suites of oxidative stress biomarkers for detecting adverse effects during environmentally relevant exposure scenarios.
Key words: oxidative stress, bivalves, in-situ bioassay, streams
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