ABSTRACT
Ecologists are using measurements of naturally-occurring stable carbon, nitrogen and sulfur isotopes to characterize energy flow and trophic interrelationships in marine, freshwater and terrestrial systems[1]. These stable isotope ratios have helped determine the contribution of terrestrial organic matter to aquatic food webs[2], an organism’s reliance on benthic versus pelagic[3] or freshwater versus marine[4] carbon, the relative trophic positioning of biota within a food web[5], and, more recently, to improve our understanding of the biomagnification (increasing concentrations of contaminants with increasing trophic level) of persistent contaminants through improved food web characterization[6]. Previous studies of contaminant accumulation in aquatic organisms have defined food webs using conventional stomach content analyses or estimated interspecies relationships[7]. Now the combination of contaminant and stable isotope analyses has enabled researchers to accurately characterize food web interactions, and, both qualify and quantify the trophic transfer of contaminants up the food chain. This review examines the recent use of stable isotope ratios in understanding contaminant movement through freshwater and marine food webs, and discusses potential applications of these isotopic measurements to future research on contaminant biomagnification.
