Zooplankton (Calanus sp., Limacina helacina, Euphasiacea, Clione limacina, Themisto sp., Paraeuchaeta sp, Hyperoche sp. and Sagitta sp.) were collected in net tows during 2003 & 2004 (onboard the CCGS Pierre Radisson and Des Groseillers) and 2005 & 2010 (onboard the CCGS Amundsen). After taxonomical sorting, samples were frozen for chemical analysis. Total mercury (THg) analysis was conducted at the Freshwater Institute, Winnipeg (DFO) using cold vapor atomic absorpotion spectrometry; monomethylmercury (MMHg) was analyzed at the University of Ottawa using gas chromatography atomic fluorescence spectroscopy; stable isotope ratios of nitrogen and carbon were run at the University of Winnipeg Isotope Laboratory using continuous flow ion ratio mass spectrometry.