Developing methods for assessing contaminant bioavailability on a coral atoll

A biomonitoring program was developed to evaluate the bioavailability of contaminants near suspected discharges from the U.S. Army Kwajalein Atoll in the Republic of the Marshall Islands. "Mussel watch" methods were adapted to meet site-specific conditions on the atoll. Critical decisions involved the selection of monitoring locations, species, and deployment methods suitable for shallow reef and harbor habitats. Due to mixing zone consideration, monitoring locations were in close proximity to discharges constraining them to shallow and/or high-energy sites. Cultured giant clams, Tridacna maxima, were selected as test organisms and transplanted to monitoring locations. Clam were secured in cages that were anchored using scaled-down coral reef mooring systems. Clams were exposed for three months and recovered and shipped to the mainland for analysis. Results suggest that giant clams were good candidates for bioaccumulation studies and that, except for very shallow exposed sites, the anchoring system was effective. Findings indicate a number of sites with potential metal contamination that require additional study. Based on initial findings a fish advisory was issued. These methods, with some suggested modifications, may be tailored to other remote sites.