A Comparative Evaluation of Oysters, Mussels and Sediments as Indicators of Trace Metals in Hong Kong Waters

Abstract

Oysters (S. glomerata = C. glomerata) taken from 20 locations revealed considerable contamination of the heavily urbanized Victoria Harbor [Hong Kong] area by Cu and Zn. Data for Cu and Zn in sediments, based on samples from 210 sites, confirmed this finding. Mussels (S bilocularis) were collected twice from 23 locations. Cu concentrations in the mussels were in qualitative agreement with the profiles derived from oyster and sediment investigations. The relative enrichment of samples from Victoria Harbor and those from elsewhere was less in mussels than in oysters and sediments, suggesting partial regulation of Cu by mussels. Zn was regulated by the mussels to a much greater extent, differences in Zn concentration between groups of samples or individual samples being minimal. No parallelism existed between oyster, sediment and mussel results with respect to Fe levels in the coastal environment of Hong Kong; presumably, the kinetics of Fe differed considerably in the 2 bivalve species. S. bilocularis was unsuitable as an indicator organism of trace metals due to partial or complete metabolic regulation. Future studies in the tropics should be coqnizant of this possibility when employing other previously unstudied bivalve species as bio-indicators.