Total and organic mercury in the starfish Ctenodiscus crispatus and the polychaete Maldanes sarsi from the Barents Sea

Total and organic mercury concentrations were measured in starfish (n = 116) and in polychaetes (n = 30) as a part of a broader ecotoxicological study of the Barents Sea. Total mercury concentration in starfish from the open sea was similar in both Arctic (0.2 μg/g dry wt.) and Atlantic (0.2 μg/g dry wt.) water masses but was higher in the samples from the coast of Novaya Zemlya (0.3 μg/g dry wt.). Though there was no difference in total mercury concentration between polychaete and starfish from the coast, there was a difference in speciation: the polychaetes had a higher percentage of methyl mercury (100%) compared to the starfish (3%). Total mercury concentration in these Barents Sea benthic invertebrates (0.25 μg/g dry wt.) was higher than in pelagic fish (0.07 μg/g dry wt.) but similar to demersal fish and particulate matter (0.25 μg/g dry wt.). They were all considered as close to pristine values.