Differences in contamination load between pelagic and sympagic invertebrates in the Arctic marginal ice zone:: influence of habitat, diet and geography

Concentration and transport of organic pollutants by Arctic sea ice may expose ice-associated fauna to high contaminant concentrations relative to pelagic organisms, Zooplankton and ice-associated amphipods were collected in the marginal ice zone near Svalbard to investigate whether habitat, diet and geographic sampling site influenced their organochlorine burden. Organochlorine concentrations were low in both zooplankton (Calanus hyperboreus, Thysanoessa inermis, Parathemisto libellula, Chaetognatha) and ice-associated amphipods (Apherusa glacialis, Gammarus wilkitzkii, Onisimus spp.), from 0.3 ng g(-1) lipid weight trans-chlordane in A. glacialis to 36.9 ng g(-1) lipid weight hexachlorobenzene (HCB) in G. wilkitzkii. Diet accounted for most of the explained organochlorine variance, followed by habitat and geographic sampling site. The concentrations were higher in carnivores (P libellula, Chaetognatha, G. wilkitzkii, Onisimus spp.) than in herbivores (C. hyperboreus, T inermis, A, glacialis), In comparison with zooplankton, ice fauna had high levels of organochlorines with high residence time in surface layers (hexachlorocyclohexane [HCH] and HCB), whereas compounds with higher particle affinity did not differ between habitats. This was attributed to the sea ice serving as a habitat that keeps ice fauna in the surface layer, rather than to the release of contaminants from the sea ice itself. HCHs were the only compounds that differed geographically, Higher alpha-/gamma-HCH ratios in C. hyperboreus and A. glacialis from the Greenland Sea relative to North of Svalbard, are consistent with the geographic patterns in HCH levels reported for air, water, ringed seals Phoca hispida and polar bears Ursus malitimus.