Governments and industries have become deeply involved in the maintenance and rehabilitation of aquatic environments to protect them from chemical degradation. To aid in this process millions of dollars are spent on collection of information on various aspects of aquatic environmental quality. An integral part of this information collection process involves the use of certain more highly exposed and sensitive organisms to indicate the integrated chemical stresses in a particular environment. The objective of this paper is to outline the advantages and disadvantages of four, avian and mammalian predators, the bald eagle, osprey, mink and otters, as indicators of aquatic environmental quality and the kinds of information on these species that could be collected to make a defensible scientific case for regulatory action. The paper starts from the premise that if these species are present and maintaining their populations, then aquatic environmental quality is probably satisfactory.
The resources that have been allocated to monitoring, have for the most part been used to determine the levels of chemicals in various materials such as water, sediments, effluents, fish and birds. A much smaller portion has been used to investigate the actual effects of chemicals on exposed organisms. There is now a growing realization that in preparing a defensible scientific case to protect or restore aquatic environmental quality it is essential to obtain data not only on levels of chemicals in the environment, but in cases of serious contamination, also on the toxicological effects that have occurred in indigenous organisms.
The criteria for selection of indicator species for monitoring exposure and effects of chemicals in the environment have been extensively reviewed and can be summarized under the following headings:
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Tendency to accumulate high levels.
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Knowledge of migratory habits, range and distribution.
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Ease of sampling and handling and of undertaking field work. 4. Knowledge of biology and physiology. Table I is a matrix of these criteria versus the four aquatic predators. Generally these four species have proved useful indicator organisms since they accumulate high levels of organochlorine chemicals and are sensitive to the toxicological properties of these chemicals. There is extensive knowledge about their biology, migratory habits, range and distribution. The mammalian species, however, tend to be fairly difficult to study in the field to obtain direct estimates of productivity and population size and