Effect of Aufwuchs Copper on Spat Settlement of the Oyster, 'Crassostrea Virginica'

摘要

Studies on the recent failure of oyster spatfall in the Chesapeake Bay have led to speculation of an unknown toxic factor at the setting site. Oyster larvae set on oyster shell surfaces normally covered with aufwuchs which may have the capacity to bind toxic metals such as copper. Over 200 oysters were collected from six mid-Chesapeake Bay sites paired for high and low spatfall. Aufwuchs samples and oyster tissue analysis indicated no significant difference in copper concentrations between paired sites. In the laboratory, aufwuchs concentrated copper from enriched estuarine water up to 20 times ambient levels in one hour, and failed to depurate copper over two hours, unlike agar (a neutral polysaccharide). Oyster larvae raised to setting stage from a single maternal spawn were exposed to copper-enriched aufwuchs surfaces.