Comparison of the Composition of Chemical Elements in the Liver of Ringed Seal (Phoca hispida) from three different populations
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- Institutt for biologi 
The ringed seal (Phoca hispida) is a circumpolar Arctic species, with several subspecies and populations. One subspecies, Phoca hispida botnica, is found in the Baltic Sea. Large ecological differences between these regions may cause variations of trophic positioning and chemical composition in tissues among the inhabiting ringed seal populations. The Baltic Sea is one of the worlds most polluted seas, and the metal pollution in this area may be problematic for Baltic ringed seals. Liver samples from juvenile ringed seals (1-3 years) from three distinct populations, in northwest Greenland, East Greenland and the Baltic Sea were collected during 2008-09. Concentrations of 42 chemical elements, including As, Cd, Hg, Pb and Se, were determined using HR-ICP-MS. Stable isotope analysis (IRMS) of δ13C and δ15N were conducted in order to reveal population differences in feeding preferences (pelagic versus benthic species) and trophic positioning, respectively. Significant differences for δ13C and δ15N were found between all three populations, and the Greenland populations showed benthic preferences and higher trophic positioning relative to the Baltic Sea. The chemical element analysis revealed spatial differences between the Baltic Sea population and either one or both of the Greenland populations for several elements. However, none of the elements of concern in the Baltic Sea were present at significantly higher concentrations in the Baltic Sea population compared to the two Greenland populations. The lower trophic positioning and preferred pelagic foraging of Baltic ringed seals contribute to protect them from impacts of their polluted habitat.