Temporal trends of mercury in Greenland ringed seal populations in a warming climate Frank Rig´ et, * a Rune Dietz a and Keith A. Hobson b Temporal trends of mercury in livers of ringed seals collected from the early 1980s to 2010 from central West, Northwest and central East Greenland were studied. In this period the climate of Greenland warmed and the influences of climate indices such as ice coverage, water temperature and the Atlantic Oscillation Index on mercury concentration were evaluated using multiple regressions and Akaike’s Information Criteria (AIC) to determine the most parsimonious models. Biological co-variables such as age, sex and trophic position (as determined by stable isotope analysis) of seals were also evaluated. Increasing levels of mercury in seals were found in Ittoqqortoormiit, central East Greenland, and Avanersuaq, Northwest Greenland, with an annual increase of +10.3 and +2%, respectively. Age was an important co-variable for all three regions and trophic position for two regions. The Atlantic Oscillation Index was also an important explanatory variable for all three regions and was positively associated with mercury concentrations in seals indicating the importance of global climatic processes on ringed seal populations in Greenland. Environmental impact The Arctic is continuing to warm. The latest AMAP assessment of climate change concluded that the sea-ice extent has decreased, surface waters in the Arctic Ocean are warming and air temperatures are increasing. These changes are likely to impact contaminant pathways and biological systems. Climate change and variability has increasingly been the scientic focus in terms of observed trends of contaminants in Arctic biota. In this manuscript we deal with temporal trends of Hg in three Greenland ringed seal populations and investigate the inuence of biological variables together with climate indices. Introduction The recent Arctic Monitoring and Assessment Programme (AMAP) assessment of mercury (Hg) temporal trends (covering the last few decades) in Arctic biota concluded that no consis- tent trend could be generalized across species and tissues for the Arctic, but recognized that some Hg time series, especially involving marine mammals, showed signicantly increasing trends. 1 This assessment also stated that these increasing trends did not match regional atmospheric Hg records, which show stable or declining trends over recent decades, and that environmental and ecological processes appear to play an increasingly important role in determining Hg trends in Arctic animals. 2 Although the signicant increase in Hg concentrations noted in present-day Arctic animals over their pre-industrial ancestors has likely been driven primarily by increases in anthropogenically released Hg, 3,4 biotic trends in recent decades may be driven by climate inuenced processes. 5 The Arctic is continuing to warm. The latest AMAP assess- ment of climate change concluded that the sea-ice extent has decreased, surface waters in the Arctic Ocean are warming and air temperatures are increasing. 6 These changes are likely to impact contaminant pathways and biological systems. 7 Climate change and variability has increasingly been the scientic focus in terms of observed trends of contaminants in Arctic biota. In a study of ringed seals (Pusa hispida) from the western Canadian Arctic, temporal trends of Hg in muscle tissue have been related to the length of the ice-free season. 8 That study found a curvilinear relationship with higher concentrations of Hg in short and long ice-free seasons than between ice-free seasons and explained that result by differ- ences in the composition of prey available to ringed seals. Also, in freshwater sh populations, climate variation has been shown to effect Hg concentrations. For example, in Canadian Mackenzie River burbot (Lota lota), Hg concentrations over the last 25 years have been strongly associated with algal-derived organic matter in a dated sediment core taken from a nearby lake. 9 Similarly, increasing Hg concentrations in Arctic char (Salvelinus alpinus) from a small lake in southwest Greenland were suggested to be related to increasing summer temperatures. 10 a Department of Bioscience, Aarhus University, Arctic Research Centre, Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark. E-mail: ffr@dmu.dk; Fax: +45 87155015; Tel: +45 87155015 b Environment Canada, 11 Innovation Blvd., Saskatoon, SK, Canada, S7N 3H5 Cite this: DOI: 10.1039/c2em30687e Received 17th August 2012 Accepted 30th October 2012 DOI: 10.1039/c2em30687e www.rsc.org/jem This journal is ª The Royal Society of Chemistry 2012 J. Environ. Monit. Journal of Environmental Monitoring PAPER Downloaded by Aarhus University Library on 15 November 2012 Published on 15 November 2012 on http://pubs.rsc.org | doi:10.1039/C2EM30687E View Online / Journal Homepage