Heavy metals in cultivated oysters (Crassostrea commercialis = Saccostrea cucullata) from estuaries of New South Wales

Abstract

Results of a survey of metal levels in the Sydney rock oyster Crassostrea commercialis are reported. Concentrations of copper, zinc, cadmium, lead and arsenic in oysters sampled from the 19 important production areas in New South Wales are generally low, and in terms of the National Health and Medical Research Council recommendations for these metals there is little or no health risk to consumers. Evidence is presented which indicates that metal concentrations decrease with increasing age and wet weight of oysters. In oysters sampled from a single estuary, there is a gradient of increasing metal concentration with increasing distance upstream from the sea. Pollution may be the cause of the relatively high concentrations in oysters from this estuary, but further work will be required to verify this. The variability of metal concentrations in oysters is discussed, and a sampling method is suggested for future monitoring of metals in this species.