Applying Trophic Tracers to Study Contaminant Levels and Trends in Arctic Marine Wildlife and Food Webs: A Review

Arctic biota are exposed to a complex suite of anthropogenicallysourced contaminants including mercury (Hg) and persistent organic pollutants (POPs). Levels of these contaminants are determined by source emissions and pathways as well biological and ecological factors. As the use of chemical tracers in trophic ecology matures and gains recognition, these tracers have increasingly been applied to study trophic influences on contaminant levels and trends in biota. The aim of this article is to review information on trophic tracer applications to contaminant studies of individuals, populations and species in and across arctic food webs. Stable isotope (SI) ratios of carbon (δ13C) and particularly nitrogen (δ15N) have been used to explain primary production source (e.g., benthic vs. pelagic) and trophic position, respectively. These SI tracers have also been used to explain variation in contaminant levels in arctic invertebrates, fish, mammals and overall food webs. Fatty acid (FA) tracers have been used only recently and in few studies to interpret Hg and POP levels in relation to diet. These studies collectively demonstrate the utility and limitations of SI and FA tracers and highlight the influence of trophic relationships, food webs and their dynamics on contaminant levels and food web bioaccumulation.