title: Mercury bioaccumulation and biomagnification in a small Arctic polynya ecosystem.
abstract: Recurring polynyas are important areas of biological productivity and feeding grounds for seabirds and mammals in the Arctic marine environment. In this study, we examined food web structure (using carbon and nitrogen isotopes, δ(13)C and δ(15)N) and mercury (Hg) bioaccumulation and biomagnification in a small recurring polynya ecosystem near Nasaruvaalik Island (Nunavut, Canada). Methyl Hg (MeHg) concentrations increased by more than 50-fold from copepods (Calanus hyperboreus) to Arctic terns (Sterna paradisaea), the abundant predators at this site. The biomagnification of MeHg through members of the food web - using the slope of log MeHg versus δ(15)N - was 0.157 from copepods (C. hyperboreus) to fish. This slope was higher (0.267) when seabird chicks were included in the analyses. Collectively, our results indicate that MeHg biomagnification is occurring in this small polynya and that its trophic transfer is at the lower end of the range of estimates from other Arctic marine ecosystems. In addition, we measured Hg concentrations in some poorly studied members of Arctic marine food webs [e.g. Arctic alligatorfish (Ulcina olrikii) and jellyfish, Medusozoa], and found that MeHg concentrations in jellyfish were lower than expected given their trophic position. Overall, these findings provide fundamental information about food web structure and mercury contamination in a small Arctic polynya, which will inform future research in such ecosystems and provide a baseline against which to assess changes over time resulting from environmental disturbance.
authors.affiliation: Canadian Rivers Institute and Biology Department, University of New Brunswick, Saint John, NB E2L 4L5, Canada. Electronic address: meredith.clayden@gmail.com.
authors.forename: Meredith G
authors.initials: MG
authors.lastname: Clayden
authors.affiliation: Canadian Rivers Institute and Biology Department, University of New Brunswick, Saint John, NB E2L 4L5, Canada; Department of Earth and Environmental Science, Acadia University, Wolfville, NS B4P 2R6, Canada; Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada.
authors.forename: Lilianne M
authors.initials: LM
authors.lastname: Arsenault
authors.affiliation: Canadian Rivers Institute and Biology Department, University of New Brunswick, Saint John, NB E2L 4L5, Canada.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Kidd
authors.affiliation: Department of Earth and Environmental Science, Acadia University, Wolfville, NS B4P 2R6, Canada.
authors.forename: Nelson J
authors.initials: NJ
authors.lastname: O'Driscoll
authors.affiliation: Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Mallory
mesh_terms: D000818:Animals; D001110:Arctic Regions; D017753:Ecosystem; D004784:Environmental Monitoring; D008628:Mercury / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D015048:Zooplankton / Q000378:metabolism*
chemical_list: D014874:Water Pollutants, Chemical; D008628:Mercury
keywords: Arctic; Biomagnification; Food web; Methylmercury; Polynya; Stable isotopes