Copper toxicity in the pacific oysterCrassostrea gigas

Abstract

A laboratory study was designed to determine the lethal concentration of Cu to the Pacific oyster. Oysters 18 to 24 months old and sexually mature were held in running unfiltered sea water (33 percent), pH8, at 12 to 15/sup 0/C for one week prior to testing. The oysters were exposed to Cu concentrations of 0.10, 0.25, 0.50, 0.75, and 1.00 ppM for three separate 96-hr experiments to determine the median tolerance limits (TL/sub m/), the concentration at which 50 percent of an experimental population are dead after 96 hours for this study. The 96-hr TL/sub m/ was estimated to be 0.56 ppM. This value is much higher than the concentrations from 0.001 to 0.010 ppM found in the natural environment. Because adult oysters were used in this study, concentrations lower than 0.56 ppM may be presumed to be lethal to the more susceptible egg and larval stages. Further studies using lower salinities and pH and higher temperatures may have elicited a lower TL/sub m/ value than 0.56 ppM.