Publication Summary

Bellingham Bay supports commercial and recreational shellfish harvest. Industrial and municipal discharges into the bay have contributed to high sediment concentrations of mercury and PCBs. To investigate potential bioaccumulation of contaminants in shellfish, crab (Cancer magister) muscle was collected from eight sites and littleneck clams (Tapes japonica, Protothaca staminea) from four sites and tested for concentrations of PCBs, other organochlorine compounds including chloropyrifos and pentachlorophenol, cadmium, arsenic, lead, and mercury. Clams were also tested for polycyclic aromatic hydrocarbons (PAH).

Bellingham Bay supports commercial and recreational shellfish harvest. Industrial and municipal discharges into the bay have contributed to high sediment concentrations of mercury and PCBs. To investigate potential bioaccumulation of contaminants in shellfish, crab (Cancer magister) muscle was collected from eight sites and littleneck clams (Tapes japonica, Protothaca staminea) from four sites and tested for concentrations of PCBs, other organochlorine compounds including chloropyrifos and pentachlorophenol, cadmium, arsenic, lead, and mercury. Clams were also tested for polycyclic aromatic hydrocarbons (PAH).

In crabs, metals ranged as follows: (Cd:0.002-0.005); As:1.9-5.6; Pb:0.05-0.29; Hg:0.06-0.15; in mg/kg wet weight). Metals in whole clams ranged as follows: (Cd:0.18-0.23; As:1.1-2.0; Pb:0.02-0.15; Hg:not detected-0.02; all mg/kg wet weight). Low concentrations of PAH were found in clams (<2-20 ppb). No pesticides or PCBs were found above detection limit in crabs or clams.

A concurrent study conducted by the Department of Natural Resources that examined crabs caught from the center of the bay found equivalent concentrations of mercury, arsenic, and lead, higher concentrations of cadmium, and detections of DDE in 2 of 7 samples (1.5, 0.6 ppb) and chlordane in 1 of 7 samples (3.7 ppb). These metals and PAH concentrations are comparable to concentrations found in Puget Sound reference areas with presumably low levels of contamination. Concentrations of mercury in Bellingham Bay crabs have declined over the last 15 years and reflect the decreased discharge of mercury into the bay.