Temporal trends of mercury in marine biota of west and northwest Greenland

Temporal trends in mercury concentrations ([Hg]) during the last two to three decades were determined in liver of shorthorn sculpin, ringed seal and Atlantic walrus from northwest Greenland (NWG, 77° N) and in liver of shorthorn sculpin and ringed seal from central west Greenland (CWG, 69° N) during the last decade. Stable-nitrogen (δ15N) and carbon (δ13C) isotope values were determined in muscle of ringed seals to provide insight into potential trophic level changes through time. Log-linear regressions on annual median [Hg] did not reveal any temporal trend in shorthorn sculpin from CWG and NWG and walrus from NWG. In ringed seals from NWG, an increase in [Hg] of 7.8% per year was observed. When based on δ15N-adjusted [Hg] this rate increased to 8.5% but was still non-significant. In ringed seal from CWG no trend was found in [Hg] during the period 1994–2004. However, during the last part of the period (1999–2004) the [Hg] increased significantly. Including tissue δ15N values as a covariate had a marked effect on these results. The annual changes in δ15N-adjusted [Hg] was estimated to −5.0% for the whole period and 2.2% during the last 5 years compared to −1.3% and 12.4%, respectively, for the non-adjusted [Hg].