Concentration and tolerance of mercury (Hg) and methylmercury (MeHg) in Arctic zooplankton

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Abstract

Arctic marine ecosystems are particularly vulnerable to Hg contamination due to the melting of polar ice, which traps Reactive Gaseous Mercury. In response to climate-induced warming, Hg concentrations in Arctic marine ecosystems are thus expected to be altered. We investigated the total Hg (THg) concentration in lower trophic level marine organisms — plankton— of different size fractions (> 200, 50- 200 and 50-20 μm) coarsely representing mesozooplankton, microzooplankton and phytoplankton, respectively, in the fjords and open sea transect along the West Coast of Greenland. In addition, we investigated the LC50 of dominant arctic zooplankton species, C. glacialis, C. finmarchicus, Pseudocalanus sp., Oithona sp. and calanoid nauplii when exposed to Hg and MeHg. The lowest THg concentration (18 ± 3.51 ng/g dw) was observed in the > 200 μm size fraction and the highest concentration (25.5 ± 3.7 ng/g dw) in the size fraction of 50-200 μm, suggesting some form of depuration of Hg in mesozooplankton. Also, planktonic organisms from fjord transects had significantly higher THg concentrations than those from the open sea. The 72-hour LC50 of Hg and MeHg decreased with decreasing prosome length and lipid content of dominant zooplankton species in the rank order of C. glacialis > C. finmarchicus > Pseudocalanus sp. > Oithona sp. > nauplii, with lower LC50 values for MeHg than for Hg. Our results demonstrate the presence of mercury in the lower trophic levels of the Arctic marine environment and species-specific responses of zooplankton to Hg pollution. Since concentrations in higher trophic level organisms such as fish are likely to depend on the concentrations at the basis of the marine food web, it is necessary to understand the potential and mechanisms of bioaccumulation in this environment.

Original languageEnglish
Title of host publication22. Danske Havforskermøde Abstract book
PublisherTechnical University of Denmark
Publication date2024
Pages41-41
Publication statusPublished - 2024
Event22. Danske Havforskermøde - DTU Aqua, Lyngby, Denmark
Duration: 23 Jan 202425 Jan 2024
Conference number: 22

Conference

Conference22. Danske Havforskermøde
Number22
LocationDTU Aqua
Country/TerritoryDenmark
CityLyngby
Period23/01/202425/01/2024

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