Influence of habitat, trophic ecology and lipids on, and spatial trends of, organochlorine contaminants in Arctic marine invertebrates

Organochlorine contaminants (OCs) and stable isotopes of carbon (δ13C) and nitrogen (δ15N) were determined in 7 benthic and 7 pelagic marine invertebrate species from the North American Arctic to identify factors influencing OC concentrations. Values of δ13C separated benthic (enriched in 13C) from pelagic species and δ15N values gave a logical approximation of trophic level (TL). With few exceptions, OC concentrations in invertebrates were low (most were <5 ng g–1 wet wt) relative to the same or similar species in temperate waters and in the range expected for lower TL Arctic organisms. Polychlorinated biphenyls (PCBs) were the predominant OC group and lower chlorinated PCB congeners and hexachlorocyclohexane (HCH) isomers were the most common individual OCs in most species. Relatively higher levels of PCBs and high proportions of highly chlorinated PCB congeners were found in a small number of the pelecypod samples (Mytilus edulis and Mya truncata), suggesting that local harbors and communities can be point sources of PCBs in the Arctic. The OC concentrations (wet wt) varied by up to 2 orders of magnitude among species and were more variable among the benthic invertebrates. Lipid content, δ13C and δ15N were significant variables related to OC concentration, but differences among species remained after accounting for these variables. Scavenging, high TL, high lipid content and local point sources can all contribute to higher OC concentrations in Arctic marine invertebrates.