Conclusions

Specimen banking is an important component in animal research and monitoring programs addressing environmental contaminants, resource status and trends, population biology, and biota health. A major goal within the coordinated research of AMMTAP and the Marine Mammal Health and Standing Response Program is to establish a stronger correlation between contaminant burdens in tissues and indices of marine mammal population health. In addition, increasing regional coverage of marine species and food webs will provide better indicators of ecosystem health.

Future Directions

Animal health

High concentrations of persistent toxic substances in marine mammals are frequently reported in the literature. These substances include both naturally occurring toxicants, such as heavy metals, as well as the anthropogenic substances, such as polychlorinated biphenyls (PCBs) and chlorinated hydrocarbon pesticides. Evidence to support the relationship between high contaminant levels in body tissues and detrimental effects to these animals has been demonstrated in only a few cases. The tendency for marine mammals to bioaccumulate contaminants reflects their relative position in food webs, tendency to accumulate large energy reserves in the form of body fat, relatively long life span, and relative ability to metabolize and excrete toxic substances.

Information on the baseline levels of environmental contaminants and toxins in marine mammal tissues is necessary to determine trends related to the health of these animals. Real-time analysis will develop these baselines and help answer questions about effects of chemical contaminants and toxins on different species and their disposition among tissues. As questions arise concerning long-term trends, new contaminants, or the validity of previous results, archived tissues can be withdrawn to address these issues.

Increasing species and food web representation

The number of animals (individuals and species) collected by AMMTAP has risen dramatically since 1992. This reflects greater attention to Department of Interior Trust Species (polar bears and Pacific walrus) in the field collections and an increasing participation by the AMMTAP cooperators. In 1998, sampling will include collections from sea otters (Gulf of Alaska), northern fur seals (Pribilof Islands, Bering Sea), and other pinniped and cetacean species harvested in Arctic and Subarctic subsistence hunts. The Project will also expand beyond marine mammals to include seabirds (murres and kittiwakes from Cook Inlet and Bering and Chukchi seas colonies) as another upper trophic level component of the Arctic marine ecosystem.

The amount of information obtained from banked specimens increases substantially if the organisms are linked ecologically. For biotic components an obvious approach is a food web framework. The transfer of anthropogenic contaminants within the marine ecosystem occurs between the aqueous matrix and the living biota and the biotic components of the food chain, with the food-based transfer dominating the higher trophic levels. Arctic food webs are relatively simple, and within the context of the existing data, offer a natural laboratory to test developing hypotheses about predator-prey patterns of bioaccumulation (e.g., Cd in Pacific walrus and bowhead whales through benthic and planktonic food webs, respectively).

continued to Bibliography

return to Alaska Contaminants and Tissue Archival Program Home