Migratory Fish as Sensors of Anthropogenic Contamination in Streams

Abstract:

Migratory fish take up metals in their stream environments, with the magnitude of uptake being dependent on the local concentration and biological pathway of the element. Some metals have long biological half-lives, and are present within fish for long periods after the fish leave the environments in which those signatures were attained. Within the Columbia River basin of western USA and Canada, tributaries have various elemental signatures of mining and industrial activity, which combined with isotopic signature of industrial elements (Hg, Cd, Pb, etc.) and natural geological isotopic variations of, e.g., Sr, allow life histories of fish to be delineated. Tributaries of the Columbia River flowing into the impounded waters above Grand Coulee Dam offer a record of contamination in fish tissues, which may be correlated with habitat signatures. Point sources, such as sulfide smelters and mining districts, allow particular streams and parts of streams to be identified from their Pb, Sr, and Cd isotopic and trace element concentration signatures. A greater number of elemental and isotopic methods employed in such studies increases the source habitat specificity of this method.