Antioxidant and detoxification responses of oysters Crassostrea hongkongensis in a multimetal-contaminated estuary.

The contaminated oysters discovered in the Pearl River Estuary (Guangdong province, China) contained high levels of metals in their tissues, especially Cu and Zn, indicating that this large and densely urbanized estuary in Southern China suffers from serious metal pollution. The present study aimed to investigate the impacts of multimetal pollution in the Pearl River Estuary on oyster antioxidant and detoxification systems. The responses of various biochemical biomarkers in the ecologically important oyster Crassostrea hongkongensis collected from 7 sites in the Pearl River Estuary were quantified. Significant correlations were demonstrated between the accumulation of Cu and Zn and oxidative stress (lipid peroxidation) and oxidative stress defenses (catalase, glutathione peroxidase) in the oyster gills. Significant correlations between the accumulation of Cd and Cu and detoxification (glutathione and glutathione transferase) in the gills were also documented. Interestingly, metallothionein concentrations were positively correlated with Cd, but negatively correlated with Cu, Ni, and Zn concentrations in the gills. These measurements indicated that Cu in the Pearl River Estuary induced various biochemical responses in the oysters and influenced the susceptibility of oysters to environmental stress. The present study has provided the first evidence of antioxidant and detoxification responses in native contaminated oysters from a field environment seriously contaminated by metals. Coupling biomarkers with tissue metal concentration measurements was a promising approach to identify the metals causing biological impacts in a multimetal-contaminated estuary. Environ Toxicol Chem 2016;35:2798-2805. © 2016 SETAC.