Accumulation and elimination of copper by the flat-tree oyster Isognomon alatus

A baseline study of copper concentrations in I. alatus from Bioluminescent Bay during May 2004 to June 2005 was conducted. In general, average copper levels were (7.64-17.1 mug/g dry wt), which are lower than those previously reported for I. alatus. The accumulation dynamics of copper by Isognomon alatus was examined in the laboratory. Accumulation of Cu was observed at concentration .0.1 mg Cu/L. Survival was 100% in oysters exposed to concentrations of 0.1-1.0 mg Cu/L. High mortality was observed at concentrations from 1.5 to 3.0 Cu mg/L after 3-5 days of exposure while the average oyster's Cu tissue content ranged 115-362 mug/g dry wt. At exposure of 3.87 mg Cu/L the oysters reached Cu concentrations of 1022 and 1259 mug/g dry wt, and 100% of mortality was observed. Furthermore, oysters exposed to 0.5 mg Cu/L for 5 days were transplanted to the field during a 14 days depuration/elimination study to determine depuration rates and biological half-lives (B.) of Cu. In average, these oysters reached a maximum of 72 mug/g dry wt within the first day of incubation and 95% of the copper accumulated was eliminated after 11 days of depuration/elimination, reaching final concentration similar to the control (13 mug/g dry wt). An average biological half-live of 6.0 days was observed thus indicating an efficient depuration capacity by I. alatus.