title: Factors affecting biotic mercury concentrations and biomagnification through lake food webs in the Canadian high Arctic.
abstract: In temperate regions of Canada, mercury (Hg) concentrations in biota and the magnitude of Hg biomagnification through food webs vary between neighboring lakes and are related to water chemistry variables and physical lake features. However, few studies have examined factors affecting the variable Hg concentrations in landlocked Arctic char (Salvelinus alpinus) or the biomagnification of Hg through their food webs. We estimated the food web structure of six high Arctic lakes near Resolute Bay, Nunavut, Canada, using stable carbon (δ(13)C) and nitrogen (δ(15)N) isotopes and measured Hg (total Hg (THg) in char, the only fish species, and methylmercury (MeHg) in chironomids and zooplankton) concentrations in biota collected in 2010 and 2011. Across lakes, δ(13)C showed that benthic carbon (chironomids) was the dominant food source for char. Regression models of log Hg versus δ(15)N (of char and benthic invertebrates) showed positive and significant slopes, indicting Hg biomagnification in all lakes, and higher slopes in some lakes than others. However, no principal components (PC) generated using all water chemistry data and physical characteristics of the lakes predicted the different slopes. The PC dominated by aqueous ions was a negative predictor of MeHg concentrations in chironomids, suggesting that water chemistry affects Hg bioavailability and MeHg concentrations in these lower-trophic-level organisms. Furthermore, regression intercepts were predicted by the PCs dominated by catchment area, aqueous ions, and MeHg. Weaker relationships were also found between THg in small char or MeHg in pelagic invertebrates and the PCs dominated by catchment area, and aqueous nitrate and MeHg. Results from these high Arctic lakes suggest that Hg biomagnification differs between systems and that their physical and chemical characteristics affect Hg concentrations in lower-trophic-level biota.
authors.affiliation: University of New Brunswick/Canadian Rivers Institute, 100 Tucker Park Rd, Saint John, NB E2L 4A6, Canada. Electronic address: glescord@gmail.com.
authors.forename: Gretchen L
authors.initials: GL
authors.lastname: Lescord
authors.affiliation: University of New Brunswick/Canadian Rivers Institute, 100 Tucker Park Rd, Saint John, NB E2L 4A6, Canada.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Kidd
authors.affiliation: Environment Canada, Aquatic Contaminants Research Division, 867 Lakeshore Rd, Burlington, ON L7S 1A1, Canada.
authors.forename: Jane L
authors.initials: JL
authors.lastname: Kirk
authors.affiliation: Acadia University, 15 University Ave, Wolfville, NS B4P 2R6, Canada.
authors.forename: Nelson J
authors.initials: NJ
authors.lastname: O'Driscoll
authors.affiliation: Environment Canada, Aquatic Contaminants Research Division, 867 Lakeshore Rd, Burlington, ON L7S 1A1, Canada.
authors.forename: Xiaowa
authors.initials: X
authors.lastname: Wang
authors.affiliation: Environment Canada, Aquatic Contaminants Research Division, 867 Lakeshore Rd, Burlington, ON L7S 1A1, Canada.
authors.forename: Derek C G
authors.initials: DC
authors.lastname: Muir
mesh_terms: D000818:Animals; D059001:Aquatic Organisms / Q000378:metabolism*; D001110:Arctic Regions; D002170:Canada; D004784:Environmental Monitoring; D020387:Food Chain; D060106:Lakes; D008628:Mercury / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D014874:Water Pollutants, Chemical; D008628:Mercury
keywords: Arctic char; Biomagnification; Food web; Mercury; Principal component analysis; Stable isotopes