THE EFFECT OF BIS-TRIBUTYLTIN OXIDE (TBTO) AND COPPER ON THE GROWTH OF JUVENILE SYDNEY ROCK OYSTERS SACCOSTREA-COMMERCIALIS (IREDALE AND ROUGHLEY) AND PACIFIC OYSTERS CRASSOSTREA-GIGAS THUNBERG

The growth of juvenile (spat) (1.25-2.62 mg dry wt) Pacific oysters C gigas and Sydney rock oysters S. commercialis was reduced by only 5 ng bis-tributyltin oxide (TBTO) 1(-1) seawater. The reduction in growth of the Pacific oysters was more severe than that of the Sydney rock oysters. When Sydney rock oyster spat were exposed to both copper and TBTO they suffered a greater reduction in growth than those exposed to only one toxicant. There was no significant interaction (P > 0.05) between the two toxicants, but an additive effect instead. Copper accumulation in Sydney rock oyster spat increased significantly (P < 0.05) 1.2-times in the presence of 20 ng TBTO 1(-1).