Nikolaus Gantner will talk on
CSI Husky Lakes: Fractionation of mercury isotopes in water, sediments, and fish from the Husky Lakes, Northwest Territories, Canada
at 12:30 in the EEB lounge (BioSciences 4338)
Mercury can accumulate in apex-predator fish muscle to concentrations exceeding those considered safe for subsistence consumption by humans. Fish species such as Lake trout are typical apex-predators of Arctic lakes and can be a significant source of food for local indigenous peoples. The influence of abiotic factors and biological parameters on Hg accumulation in apex-predators are not well understood. Further, a good understanding of sources of Hg to and processes within water column and food webs is still lacking. Our study aims to investigate the interactions of water column, food webs and Hg transfer in aquatic systems in the Inuvialuit Settlement Region (Canada). The selected Husky Lakes, Yaya, and Noell Lake ecosystems represent a range of water column and ecological characteristics, as well as Hg delivery (marine-, riverine- or freshwater-derived). We investigate how those characteristics affect Hg transfer and fractionation. All lakes are frequented by the Inuvialuit communities Inuvik and Tuktoyaktuk for subsistence fishing. Sampling includes surface water, benthic and pelagic invertebrates, tissues from harvested fishes, and non-target fishes. Biological parameters of fishes (age, length, weight, diet) are recorded and invertebrates separated by species. Sample analysis includes total Hg (THg), monomethylHg (MeHg), and stable isotopes of carbon (δ13C), nitrogen (δ15N), and Hg (δxHg) and otolith microchemistry. Hg IRs are analyzed by multi-collector inductively coupled plasma mass spectrometry (MC-ICP/MS). Hg mass independent fractionation (MIF; Δ199Hg) and mass dependent fractionation (MDF; δ202Hg) was calculated and evaluated against conditions in the water column, food web transfer and the potentially difference in Hg delivery. We demonstrate that MIF varies in Lake Trout from different lakes up to ~2‰; We will present new results from this multidisciplinary study and discuss our preliminary findings with particular focus on implications for future research efforts in a changing Arctic environment.
Nikolaus is the founder/owner of Gantner Consulting Services and is affiliated with the Dept of Chemistry at Trent University. He holds an MSc in Zoology from the University of Innsbruck (Austria), a PhD in Environmental Biology and Toxicology from the University of Guelph, and then completed an NSERC Visiting Fellowship in Government Laboratories with Environment Canada at the Water and Climate Impacts Research Centre (Victoria, BC).
Everyone is welcome to attend
Coffee and cookies right after the seminar