Physiological and cellular responses of oysters (Crassostrea hongkongensis) in a multimetal-contaminated estuary.

The Pearl River estuary, southern China, suffers from multiple sources of metal contamination as a result of the rapid industrial development in the region; but the biological impacts of contamination remain unknown. In the present study, a euryhaline oyster, Crassostrea hongkongensis, was collected from different sites of the Pearl River estuary; and various physiological (heart rate, alkaline phosphatase as homeostatic regulation, and glycogen as energy reserve) and cytological (lysosomal membrane stability) biomarkers were quantified to assess this species as a potential bioindicator of metal pollution in contaminated areas. Large variations of metal accumulation levels in the oysters were documented, especially for copper (Cu), zinc (Zn), cadmium (Cd), chromium, and nickel (Ni). Among these metals, the authors demonstrated significant correlations between the digestive gland metal accumulation of Cu, Zn, and Ni and the cellular homeostasis (alkaline phosphatase) and glycogen reserves. Heart rate was positively correlated with Cd but negatively correlated with Cu and Zn concentrations in the gills. Lysosomal membrane stability was significantly inhibited at the most contaminated sites but had no relationship with the accumulated metal concentrations. These measurements indicate that multimetal contamination in the Pearl River estuary impacts the physiological and cytological performance of oysters. Environ Toxicol Chem 2016;35:2577-2586.