Influence of diet and sea ice drift on organochlorine bioaccumulation in Arctic ice-associated amphipods

The drifting sea ice has been suggested as important in the transport and concentration of organic matter and pollutants in the Arctic. We collected sea ice-associated amphipods in the marginal ice zone north of Svalbard and in the Fram Strait in September 1998 and 1999 to assess contaminant accumulation in ice-associated organisms. Organochlorine concentrations increased from the more herbivorous Apherusa glacialis to the more carnivorous Gammarus wilkitzkii and the more necrophagous Onisimus spp. The relative contribution of compound classes to the sum of organochlorines differed between the amphipod families, with a higher relative contribution of hexachlorocyclohexanes (HCHs) in A. glacialis. The composition of the compound classes HCHs. chlordanes and dichlorodiphenyltrichloroethanes (DDTs) was similar between the amphipod families, whereas the profiles of polychlorinated biphenyls (PCBs) differed. The occurrence of organochlorines differed spatially, with higher alpha-HCH concentrations in amphipods from the Fram Strait in comparison with amphipods collected north of Svalbard. This could be related to the sea ice drift route, since sea ice in the Fram Strait had a drift route across the central Arctic Ocean, while the sea ice north of Svalbard had a western drift route to the sampling stations. Even though marine invertebrates have direct uptake by passive diffusion of contaminants across their gills. our results imply that the species' ecology such as diet is important in the bioaccumulation process of organic pollutants. In addition, the results show that sea ice drift route influences the concentrations of organochlorine pollutants in ice-associated organisms.