Do concentrations in eggs and liver tissue tell the same story of temporal trends of mercury in high Arctic seabirds?

Mercury (Hg) remains a key contaminant of concern in Arctic biota, and monitoring of Hg concentrations in seabird tissues will be an effective approach to track the effects of implementing the Minamata Convention. We examined trends in total Hg (THg) in liver and egg tissues of two Arctic seabirds, thick-billed murres (Uria lomvia) and northern fulmars (Fulmarus glacialis), between 1976 and 2013 to assess whether both tissues showed similar patterns of Hg change. Hepatic THg was consistently higher than egg THg, and both species had similar egg THg concentrations, but fulmars had higher hepatic THg than murres. Murre THg concentrations showed more relative variation through time than fulmars. We suggest that egg THg better reflects exposure of birds to THg in local, Arctic prey, whereas liver THg may incorporate longer term, year-round THg exposure. Additional analysis of THg distribution in Arctic seabirds post-laying would help inform interpretation of long-term trends.