Date of Award
Master of Science
Heavy metals have been detected in aquatic and terrestrial environment around the Paducah Gaseous Diffusion Plant (PGDP). However, little is known regarding their accumulation and associated effects in turtles inhabiting aquatic ecosystems near the PGDP. The current study was initiated to evaluate accumulation of heavy metals and its associated effects in aquatic turtle species and to determine species composition and abundance in ponds near the PGDP. A total of 382 turtles composed of 6 species were captured at 6 ponds during 2007 and 2008. Red-eared slider turtles (Trachemys scripta elegans) were the most abundant species (81.2% of the total number of turtles captured), and the abundance and densities ranged from 12 to 88 turtles and from 39 to 122 turtles/ha among study ponds, respectively. Only Cu concentrations in liver tissue differed among ponds, which may be associated with the age of one study pond. However, a gradient of increasing concentrations from ponds upstream to ponds midstream and downstream of the PGDP was observed for Pb and Hg in liver. Copper and Hg were detected in red-eared slider eggs. Copper concentrations in eggs were positively correlated with female Cu concentrations in kidney. Metal concentrations in turtle tissues and sediment were lower than previously reported concentrations associated with adverse effects. Total white blood cell counts, ratios of heterophils to lymphocytes, numbers of lymphocytes and eosinophils, and T-cell mediated immunity were correlated with metal concentrations. Hematocrits were not correlated with any metal concentrations in any tissues. Hemoparasites were observed in 40.7% of the red-eared slider turtles studied. Concentrations of heavy metals in turtle tissues, eggs, and sediment measured in the current study were low, and are not thought to be adversely affecting aquatic turtles near the PGDP. Although some hematological and immunological indices were correlated with some metal concentrations, further studies are needed to determine if these effects are associated with metal exposure, with hemoparasites, or other contaminants or disease.
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