Contaminants in oysters in Kaneohe Bay, Hawaii

Despite past and present concerns about the toxicity and persistence of various environmental contaminants (heavy metals and pesticides), relatively few studies have documented their concentrations in tropical or sub-tropical marine ecosystems. In this investigation, a ‘mussel watch’ approach was applied in Kaneohe Bay, Hawaii, to assess the present levels of potential contaminants in the Pacific oyster, Crassostrea gigas. Geographical gradients of these contaminants were observed and related to what is known about past and present inputs. Concentrations of lead, copper, chromium and zinc were elevated in oyster tissues near stream mouths in the southern watersheds of Kaneohe Bay. Dieldrin and chlordane concentrations in oysters from one of these sites exceeded the US Environmental Protection Agency's screening levels to protect human health, and were much higher than in oysters from the east and Gulf coasts of the temperate mainland USA.