The detection of pollutant impact in marine environments: condition index, oxidative DNA damage, and their associations with metal bioaccumulation in the Sydney rock oyster Saccostrea commercialis.

Specimens of the Sydney rock oyster Saccostrea commercialis were deployed for a 3-month period at control and sewage disturbed marine locations in the Hunter Region, New South Wales, Australia. The DNA damage product,8-hydroxyguanine, was measured by GC/MS-SIM from chromatin extracts of the gill tissues of oysters to assess oxidative damage. The levels ranged from 11.5 to 18.8 modified bases per 10(7) guanine bases. Although the condition indices were significantly different between the Redhead control site (178.3+/-3. 6) and the Burwood sewage disturbed location (140.4+/-4.4), no significant differences in 8-hydroxyguanine concentrations were detected between the sites, and the concentration of 8-hydroxyguanine was not correlated to condition index. However, levels of the DNA base modification were correlated with the concentrations of bioaccumulated lead (r=0.84, P=0.036). This association provides in vivo evidence that the bioaccumulation of lead results in oxidative damage to DNA. An additional control and sewage disturbed site were included to investigate the relationship between heavy metal bioaccumulation and the condition index of deployed oysters. After the 3-month deployment period, the condition index was negatively correlated to concentrations of bioaccumulated mercury (r=-0.80, P<0.001), cobalt (r=-0.65, P<0.01), and nickel (r=-0.69, P<0.01), suggesting a strong negative influence of these metals at relatively low concentrations on the physiological condition of the oysters.