Exposure and response of aquacultured oysters, Crassostrea gigas, to marine contaminants

Comparative growth rates were monitored in the Pacific oyster, Crassostrea gigas, at two sites in Singapore, one uncontaminated and the other contaminated with respect to ambient seawater quality. Growth rates differed significantly at the two sites, revealing that marine water quality can have potentially adverse effects for the oyster aquaculture industry in Singapore. Shell abnormalities (chambering) were observed for juvenile and mature oysters at the contaminated site. Water quality parameters including temperature, salinity, dissolved oxygen, total organic carbon and chlorophyll-a were essentially similar at both sites. Differences in the levels of tributyl tin detected in soft tissues were not observed, but significant differences in the burden of persistent organic pollutants (POPs) existed between the two sites. On a positive note, the effects of pollution on oysters were found to be reversible, where transplantation of individuals to the uncontaminated site resulted in the ability of C. gigas to recover in terms of growth rate and the burden of bioaccumulated POPs.