Search

Size scaling of the accumulation of four trace metals was examined in the infaunal clam Amiantis umbonella in Kuwait Bay. In clams of varying shell length (2.5–5 cm), soft tissue growth in A. umbonella from a contaminated site was inhibited compared with clams from a less contaminated reference site. Body burdens of all four metals were positively correlated with clam soft tissue wet weight, but for Cd, Cu, and Pb, correlations were stronger in clams from the contaminated site (r2 = 0.6–0.9, p < 0.001) than the reference site (r2 = 0.2–0.3, p < 0.002). Scaling factors for the accumulation of Cd, Cu, and Pb in the soft tissues of A. umbonella from both sites were not significantly different than 1, indicating that clams accumulated these metals in proportion to growth with little regulation. The scaling factor of Hg in clams from the contaminated site also was 1 but was 0.5 and 2.4 for high and low Hg accumulating subpopulations of clams from the reference site, respectively. The greater retention of Hg with respect to growth in clams from the reference site than from the contaminated site requires further investigation to determine differences in Hg bioavailability at the two sites and the form of Hg these clams accumulate. [ABSTRACT FROM AUTHOR]

The objectives of this study were to evaluate the infaunal, facultative deposit-feeding clam Amiantis umbonella as a bioindicator of trace-metal contamination and the relative importance of clam burrow sediment and porewater to total accumulation in an urban/industrial coastal environment. Concentrations of eight trace metals (cadmium [Cd], chromium, copper, mercury [Hg], nickel, lead [Pb], vanadium, and zinc) were measured in the soft tissues of clams and in sediment and porewater from clam burrows along a 5-km transect from desalination/power plant discharges in inner Kuwait Bay. All metals had significantly greater concentrations in clams collected near the desalination/power plant discharges than from the reference site and exhibited decreasing trends with distance from the point source in clam soft tissues and burrow sediment and porewater. Concentrations of Hg (1-9 ppm [dry weight]) and the highest concentrations of Pb (3 ppm) and Cd (7 ppm) in clams from contaminated sites in Kuwait Bay were greater than human consumption limits. Metal concentrations in clams were correlated with those in burrow sediment and porewater across all sites and at sites closest to the point source but not within the reference site. The concentrations of all metals, except Pb, in clams from the contaminated sites were more highly correlated with those in clam burrow sediment than porewater. Concentrations of Pb in clam soft tissues were more strongly correlated with those in burrow porewater than sediment. These results indicate that A. umbonella is an excellent bioindicator of trace metal contamination and that sediment is an important source of contaminant metals to this infaunal clam; however, the source of each metal must be evaluated separately.