Role of chemical and ecological factors in trophic transfer of organic chemicals in aquatic food webs

Trophic transfer of chlorinated organic contaminants was investigated in an aquatic community composed of zooplankton, benthic invertebrates, and fish . Biomagnification, measured as the increase in lipid-based chemical concen trations in predator over that in prey, was observed for high-K-OW chemical s (log K-OW > 6.3). Low-K-OW chemicals (log K-OW < 5.5) did not biomagnify in the food web, and chemicals with log K-OW between 5.5 and 6.3 showed som e evidence of biomagnification. Trophic level differences in chemical accum ulation in the food web could not be attributed to bioconcentration into in creasing trophic levels with increasing lipid levels, as no relationship wa s observed between trophic position and lipid content of organisms. Plots o f contaminant-ordinated principal component scores in component space predi cted the detailed diets of the species examined. It is concluded that(1) tr ophic interactions play a crucial role in the distribution of high-K-OW che micals but not for low-k(OW) chemicals and that (2) contaminant distributio ns provide a means to determine structure in aquatic communities.