Influence of pesticides on marine ecosystems

Abstract

A bioassay programme undertaken in 1958 has evaluated the toxicity of about 240 pesticides to estuarine fauna. Studies indicate that chronic levels of sublethal amounts of pesticides may have more damaging effects than transitory changes due to acutely toxic levels of pollution. The first five years of a programme monitoring the incidence of synthetic pesticide residues in populations of North American shellfish has been completed. The results demonstrate the ubiquity of DDT and its metabolites. Levels of contamination, however, are not high enough to indicate a human health problem. The run-off of surface waters from agricultural districts is indicated as the chief source of this type of pollution; municipal and industrial wastes, and the control of noxious insects are regionally important sources. Observations of laboratory populations experimentally contaminated with DDT indicate, by extrapolation, that pesticide pollution is causing significant changes in mortality, growth rates, or resistance to disease in some marine populations.