Implications of aquatic animal health for human health.

Human health and aquatic animal health are organically related at three distinct interfaces. Aquatic animals serve as important contributors to the nutritional protein, lipid, and vitamin requirements of humans; as carriers and transmitters of many infectious and parasitic diseases to which humans are susceptible; and as indicators of toxic and carcinogenic substances that they can convey, in some part, from aquatic environments to man and other terrestrial animals. Transcending these relationships, but less visible and definable to many, is the role that aquatic animals play in the sustenance of our integrated planetary ecosystem. Up to the present, this ecosystem has been compatible with mankind's occupation of a niche within it at high but ultimately limited population levels. In the past century we have become clearly aware that human activities, particularly over-harvesting of aquatic animals together with chemical degradation of their habitats, can quite rapidly lead to perturbances that drastically shift aquatic ecosystems toward conditions of low productivity and impaired function as one of earth's vital organs. The negative values of aquatic animals as disease vectors are far outweighed by their positive values as nutritional sources and as sustainers of a relatively stable equilibrium in the global ecosystem. In the immediate future we can expect to see increased and improved monitoring of aquatic habitats to determine the extent to which aquatic animals cycle anthropogenic toxic and carcinogenic chemicals back to human consumers. In the long term, methods are particularly needed to assess the effects of these pollutants on reproductive success in aquatic communities and in human communities as well. As inputs of habitat-degrading substances change in quality and quantity, it becomes increasingly urgent to evaluate the consequences in advance, not in retrospect. A new, more realistic and comprehensive philosophy regarding aquatic environmental preservation and equally new and comprehensive technological advances reflective of this philosophy will be required. In the next century we will see a serious test of whether or not mankind has lost its ability to foresee and forestall the side effects of scientific and technological ingenuity.