ROCK OYSTER SACCOSTREA-GLOMERATA AS AN INDICATOR OF TRACE-METALS IN HONG-KONG

An urgent need for a subtropical and tropical indicator organism for use in the biological monitoring of pollutants is recognized. Preliminary studies were undertaken to test the indicator ability of the rock oyster S. glomerata (= Crassostrea glomerata Gould) for monitoring the trace metals, Cd, Cu, Fe and Zn. A survey of these trace metals in rock oysters from 54 sites in Hong Kong waters revealed elevated levels of metals in several areas. Profiles of metal abundance in S. glomerata agreed substantially with the distribution of industrial and domestic discharges in Hong Kong and with patterns of contamination found in studies of the Pacific oyster C. gigas and of sediments. Application of POLYDIV statistical analysis to these data aided interpretation and confirmed the relationship between known areas of contamination and elevated metal levels in S. glomerata. This oyster, which exhibits an unusually great capacity to accumulate a range of elements from the ambient environment, appears to be a reliable indicator organism and may be of great value in global monitoring studies.