Relationships Between Levels of Radiocaesium in Components of Terrestrial and Aquatic Food Webs of a Contaminated Streambed and Floodplain Community

Abstract

(1) Radiocaesium concentrations of plants and animals from the watershed of a former reactor effluent stream declined 50-98% from 1971 to 1981. (2) Radiocaesium concentrations of animals did not differ significantly between samples from locations along the stream channel, reflecting a previously demonstrated uniform distribution of radiocaesium in the sediments, and did not differ between animals from terrestrial vs. aquatic food webs. (3) Significant correlations between radiocaesium contents of food-web components were about twice as frequent as would be expected by chance, but only seven of the twentythree significantly correlated pairs contained components that were likely to have a direct trophic association. (4) Caution should be used in arguing causation on the basis of simple correlations of contaminant levels of biotic compartments alone. (5) The best 'indicator species' for radiocaesium contamination in aquatic food webs were the plants Typha and Polygonum and, even better, the animals Palaemonetes and Etheostoma. In terrestrial food webs, the best indicators were the plants Alnus and Salix and the animal groups of Araneae, Odonata (damsel flies) and Orthoptera.