Trace metal bioavailability in southeastern United States estuaries: Bioaccumulation and effects on glucose absorption in the eastern oyster, Crassostrea virginica.

摘要

Anthropogenic contaminant enrichment in estuarine systems is a concern due to projected increased population growth and accompanying developmental pressures. Trace metals, one class of pollutants closely associated with urbanization, are of particular concern due to their unavoidable use, their persistence in the environment, and their known toxicity. The ability to predict metal concentrations at which bioaccumulation and degradation of natural resources occurs is needed. The goals of this study were: (1) examine and characterize trace metal pollution, toxicity (Sediment Quality Guideline = SQG), and bioavailability (Acid Volatile Sulfide = AVS); (2) evaluate condition, gonadal, and growth indices of the oyster, Crassostrea virginica, in relation to trace metal exposure and bioaccumulation; and (3) examine effects of trace metal exposure on glucose uptake processes in the hepatopancreatic tissue of adult oysters.; Results indicated that AVS metals (Cd, Cu, Pb, Ni, Zn, and Hg) were elevated in developed areas of Charleston, Savannah, and St. Simons estuaries compared to ACE Basin. AVS metal concentrations in tidal creeks of the Charleston estuary were higher than rivers/harbor sites. Rivers/harbor sites from all estuaries had a high occurrence of bioavailability (AVS approach) but a low occurrence of SQG excursions. Tidal creeks of Charleston Harbor had a low occurrence of bioavailability (AVS approach) but a high occurrence of SQG excursions.; Oysters were exposed to elevated sediment AVS metals in urban/industrial sites relative to agricultural, suburban, and reference sites. Oyster tissue site to site metal bioaccumulation showed less variability as compared to sediment variability. The AVS approach had a 51.1% likelihood of correctly predicting (+ or −) of metals in oysters. The SQG approach had a 57.7% likelihood of correctly predicting (+ or −) of metals in oysters. Adult oyster indices showed no significant adverse effects resulting from contaminant exposure levels.; Copper and cadmium were both accumulated in tissues of the oyster during in vitro studies. In vitro cadmium exposures ≤50 ppm had no effects on glucose accumulation in oyster hepatopancreatic tissues while in vitro copper exposures ≥10 ppm had significant adverse effects. Acute in vivo exposures to Cd or Cu resulted in no adverse effects in glucose accumulation.