title: Changes in food web structure alter trends of mercury uptake at two seabird colonies in the Canadian Arctic.
abstract: Arctic ecosystems are changing in response to climate change and some Arctic food web structures are being affected in ways which may have potential consequences for the biomagnification of environmental contaminants. Here, we examined how a shift in diet of an Arctic seabird resulted in a change of trophic position and how that change affected exposure to mercury over time. The thick-billed murre (Uria lomvia), which breeds in the eastern Canadian Arctic, has been monitored for diet and environmental contaminants at two colonies, one in northern Hudson Bay and one in the high Arctic. As a result of a change in diet, murres breeding in Hudson Bay lowered their trophic position which, in turn, should affect their mercury exposure over time. After adjusting mercury concentrations in murre eggs for trophic position, the temporal trend of mercury in Hudson Bay murre eggs changed from nonsignificant to a significantly increasing trend. Valid trends can be deduced only when factors, such as diet, have been taken into account.
authors.affiliation: Environment Canada, National Wildlife Research Centre, Carleton University , Raven Road, Ottawa, Ontario Canada K1A 0H3.
authors.forename: Birgit M
authors.initials: BM
authors.lastname: Braune
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Gaston
authors.forename: Keith A
authors.initials: KA
authors.lastname: Hobson
authors.forename: H Grant
authors.initials: HG
authors.lastname: Gilchrist
authors.forename: Mark L
authors.initials: ML
authors.lastname: Mallory
mesh_terms: D000818:Animals; D001110:Arctic Regions; D002170:Canada; D046091:Charadriiformes / Q000378:metabolism*; D057231:Climate Change; D004032:Diet; D004784:Environmental Monitoring; D020387:Food Chain; D062312:Islands; D008628:Mercury / Q000378:metabolism*; D009425:Nesting Behavior; D009587:Nitrogen Isotopes
chemical_list: D009587:Nitrogen Isotopes; D008628:Mercury