title: Using sulfur stable isotopes to assess mercury bioaccumulation and biomagnification in temperate lake food webs.
abstract: Nitrogen and carbon stable isotopes (δ15N, δ13C) are commonly used to understand mercury (Hg) bioaccumulation and biomagnification in freshwater food webs. Though sulfur isotopes (δ34S) can distinguish between energy sources from the water column (aqueous sulfate) and from sediments to freshwater organisms, little is known about whether δ34S can help interpret variable Hg concentrations in aquatic species or food webs. Seven acidic lakes in Kejimkujik National Park (Nova Scotia, Canada) were sampled for biota, water, and sediments in 2009 and 2010. Fishes, zooplankton, and macroinvertebrates were analyzed for δ34S, δ15N, δ13C, and Hg (methyl Hg in invertebrates, total Hg in fishes); aqueous sulfate and profundal sediments were analyzed for δ34S. Within lakes, mean δ34S values in sediments and sulfate differed between 0.53‰ and 1.98‰, limiting their use as tracers of energy sources to the food webs. However, log-Hg and δ34S values were negatively related (slopes -0.14 to -0.35, R20.20-0.39, p < 0.001-0.01) through each food web, and slopes were significantly different among lakes (analysis of covariance, lake × δ34S interaction term p = 0.04). Despite these relationships, multiple regression analyses within each taxon showed that biotic Hg concentrations were generally better predicted by δ15N and/or δ13C. The results indicate that δ34S values are predictive of Hg concentrations in these food webs, although the mechanisms underlying these relationships warrant further study. Environ Toxicol Chem 2017;36:661-670. © 2016 SETAC.
authors.affiliation: Canadian Rivers Institute and Biology Department, University of New Brunswick, Saint John, New Brunswick, Canada.
authors.forename: Meredith G
authors.initials: MG
authors.lastname: Clayden
authors.affiliation: Canadian Rivers Institute and Biology Department, University of New Brunswick, Saint John, New Brunswick, Canada.
authors.forename: Gretchen L
authors.initials: GL
authors.lastname: Lescord
authors.affiliation: Canadian Rivers Institute and Biology Department, University of New Brunswick, Saint John, New Brunswick, Canada.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Kidd
authors.affiliation: Aquatic Contaminants Research Division, Canada Centre for Inland Waters, Environment Canada, Burlington, Ontario, Canada.
authors.forename: Xiaowa
authors.initials: X
authors.lastname: Wang
authors.affiliation: Aquatic Contaminants Research Division, Canada Centre for Inland Waters, Environment Canada, Burlington, Ontario, Canada.
authors.forename: Derek C G
authors.initials: DC
authors.lastname: Muir
authors.affiliation: Department of Earth and Environmental Science, Acadia University, Wolfville, Nova Scotia, Canada.
authors.forename: Nelson J
authors.initials: NJ
authors.lastname: O'Driscoll
mesh_terms: D000818:Animals; D059001:Aquatic Organisms / Q000187:drug effects / Q000378:metabolism*; D004784:Environmental Monitoring / Q000379:methods*; D005399:Fishes / Q000378:metabolism; D020387:Food Chain; D007448:Invertebrates / Q000187:drug effects / Q000378:metabolism; D060106:Lakes / Q000737:chemistry*; D008628:Mercury / Q000032:analysis / Q000378:metabolism*; D009674:Nova Scotia; D013460:Sulfur Isotopes; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*; D015048:Zooplankton / Q000187:drug effects / Q000378:metabolism
chemical_list: D013460:Sulfur Isotopes; D014874:Water Pollutants, Chemical; D008628:Mercury
keywords: Acidic lake; Bioavailability; Biomagnification; Food web; Methylmercury; Stable isotope; Sulfur; Trophic transfer