The data presented herein represents Phase II of a two-part program to evaluate levels of heavy metals, polychlorinated biphenyls (PCBs) and polycyclic aromatic [hydrocarbons] (PAHs) in abiotic and biotic components of four harbor environments on Guam. Phase I focused on sediments and clearly identified areas of enrichment for all three contaminant groups in Agana Boat Basin, the outer portion of Apra Harbor, and the Merizo Pier area. The data from this investigation were presented and discussed at length in an earlier report (Denton et al. 1997).

In the present study, all four harbors were revisited and dominant biotic representatives were collected in order to evaluate contaminant movement into marine food chains. The sampling sites ranged from relatively enriched through to relatively clean, and were identified during Phase I of the study. The dominant biotic groups considered were algae, sponges, soft and hard corals, sea cucumbers, bivalves, and fish. Representatives of each were collected from all four harbor locations. In addition, a limited number of ascidians, an octopus, and a stomatopod crustacean were collected from Apra Harbor.

The findings of the survey were evaluated, following blushed a detailed comparative analysis with published findings, for similar and related species from elsewhere. It was concluded that Guam's harbor environments are generally clean by world standards, although mild to moderate enrichment of the biota with arsenic, copper, lead, mercury, tin, and PCBs was evident at certain sites.

Oysters from Agana Boat Basin and Apra Harbor were heavily contaminated with copper and zinc. Sponges, soft corals and sea cucumbers from Apra Harbor also contained relatively high concentrations of arsenic, presumably reflecting releases of this element from fuel combustion as well as from past uses in biocides and wood preservatives. All three biotic groups from this location were also relatively enriched with PCBs, a feature they had in common with the majority of fish captured here. Sea cucumbers and fish from Apra Harbor also contained higher mercury concentrations than specimens from the other harbor sites.

The data for tin contrasted sharply with the findings described above. For this element, levels were appreciably higher in sponges, soft corals and sea cucumbers from within the smaller boat harbors compared with those from Apra Harbor. These findings are in line with reports from elsewhere, that marinas and small boat harbors are generally more prone to tin (TBT) problems than larger ports and harbors, a factor attributed to the higher density of boating traffic and permanently moored watercraft. However, they are not supported by our previous sediment data for tin at each of these locations.

None of the fish or shellfish contained levels of any contaminant that exceeded current U.S. FDA food standards or guidance limits. The absence of an FDA food standard for copper and zinc was duly noted in light of the high levels of these metals in oyster from Agana Boat Basin and Apra Harbor. Levels found in these bivalves frequently exceeded the Australian food standards for both elements. There was no evidence to support an increase in the biological availability of silver, chromium, nickel or PAHs at any of the harbor sites examined.