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Laske SM, Burke SM, Carey MP, Swanson HK, Zimmerman CE. Investigating effects of climate-induced changes in water temperature and diet on mercury concentrations in an Arctic freshwater forage fish. ENVIRONMENTAL RESEARCH 2023; 218:114851. [PMID: 36414108 DOI: 10.1016/j.envres.2022.114851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 10/28/2022] [Accepted: 11/16/2022] [Indexed: 06/16/2023]
Abstract
The amount of mercury (Hg) in Arctic lake food webs is, and will continue to be, affected by rapid, ongoing climate change. At warmer temperatures, fish require more energy to sustain growth; changes in their metabolic rates and consuming prey with potentially higher Hg concentrations could result in increased Hg accumulation. To examine the potential implications of climate warming on forage fish Hg accumulation in Arctic lakes, we quantified growth and Hg accumulation in Ninespine Stickleback Pungitius pungitius under different temperature and diet scenarios using bioenergetics models. Four scenarios were considered that examined the role of climate, diet, climate × diet, and climate × diet × elevated prey Hg. As expected, annual fish growth increased with warmer temperatures, but growth rates and Hg accumulation were largely diet dependent. Compared to current growth rates of 0.3 g⋅y-1, fish growth increased at least 200% for fish consuming energy-dense benthic prey and decreased at least 40% for fish consuming pelagic prey. Compared to baseline levels, the Hg burden per kilocalorie of Ninespine Stickleback declined up to 43% with benthic consumption - indicating strong somatic growth dilution - but no more than 4% with pelagic consumption; elevated prey Hg concentrations led to moderate Hg declines in benthic-foraging fish and Hg increases in pelagic-foraging fish. Bioenergetics models demonstrated the complex interaction of water temperature, growth, prey proportions, and prey Hg concentrations that respond to climate change. Further work is needed to resolve mechanisms and rates linking climate change to Hg availability and uptake in Arctic freshwater systems.
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Affiliation(s)
- Sarah M Laske
- U. S. Geological Survey, Alaska Science Center, Anchorage, AK, USA.
| | - Samantha M Burke
- Department of Biology and Water Institute, University of Waterloo, Waterloo, Ontario, Canada
| | - Michael P Carey
- U. S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Heidi K Swanson
- Department of Biology and Water Institute, University of Waterloo, Waterloo, Ontario, Canada
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Burke SM, Zimmerman CE, Laske SM, Koch JC, Derry AM, Guernon S, Branfireun BA, Swanson HK. Fish growth rates and lake sulphate explain variation in mercury levels in ninespine stickleback (Pungitius pungitius) on the Arctic Coastal Plain of Alaska. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 743:140564. [PMID: 32758814 DOI: 10.1016/j.scitotenv.2020.140564] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/24/2020] [Accepted: 06/25/2020] [Indexed: 06/11/2023]
Abstract
Mercury concentrations in freshwater food webs are governed by complex biogeochemical and ecological interactions that spatially vary and are often mediated by climate. The Arctic Coastal Plain of Alaska (ACP) is a heterogeneous, lake-rich landscape where variability in mercury accumulation is poorly understood. Earlier research indicated that the level of catchment influence on lakes varied spatially on the ACP, and affected mercury accumulation in lake sediments. This work sought to determine drivers of spatial variation in mercury accumulation in lake food webs on the ACP. Three lakes that were a priori identified as "high catchment influence" (Reindeer Camp region) and three lakes that were a priori identified as "low catchment influence" (Atqasuk region) were sampled, and variability in water chemistry, food web ecology, and mercury accumulation was investigated. Among-lake differences in ninespine stickleback (Pungitius pungitius) length-adjusted methylmercury concentrations were significantly explained by sulphate concentration in lake water, a tracer of catchment runoff input. This effect was mediated by fish growth, which had no pattern between regions. Together, lake water sulphate concentration and fish age-at-size (proxy for growth) accounted for nearly all of the among-lake variability in length-adjusted methylmercury concentrations in stickleback (R2adj = 0.94, p < 0.01). The percentage of total mercury as methylmercury (a proxy for net Hg methylation) was higher in sediments of more autochthonous, "low catchment influence" lakes (p < 0.05), and in the periphyton of more allochthonous, "high catchment influence" lakes (p < 0.05). The results indicate that dominant sources of primary production (littoral macrophyte/biofilm vs. pelagic phytoplankton) and food web structure (detrital vs. grazing) are regulated by catchment characteristics on the ACP, and that this ultimately influences the amount of methylmercury in the aquatic food web. These results have important implications for predicting future mercury concentrations in fish in lakes where fish growth rates and catchment inputs may change in response to a changing climate.
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Affiliation(s)
- S M Burke
- Department of Biology and Water Institute, University of Waterloo, 200 University Ave. West, Waterloo, Ontario N2L 3G1, Canada; Environment and Climate Change Canada (ECCC), Aquatic Contaminants Research Division, 867 Lakeshore Rd., Burlington, ON L7S 1A1, Canada.
| | - C E Zimmerman
- U. S. Geological Survey, Alaska Science Center, 4210 University Dr., Anchorage, AK 99508, USA
| | - S M Laske
- U. S. Geological Survey, Alaska Science Center, 4210 University Dr., Anchorage, AK 99508, USA
| | - J C Koch
- U. S. Geological Survey, Alaska Science Center, 4210 University Dr., Anchorage, AK 99508, USA
| | - A M Derry
- Département des sciences biologiques, Université du Québec à Montréal (UQAM), P.O. Box 8888, Succ. Centre-Ville, Montréal, Québec H3C 3P8, Canada
| | - S Guernon
- Département des sciences biologiques, Université du Québec à Montréal (UQAM), P.O. Box 8888, Succ. Centre-Ville, Montréal, Québec H3C 3P8, Canada
| | - B A Branfireun
- Western University, Department of Biological Sciences, London, Ontario N6A 3K7, Canada
| | - H K Swanson
- Department of Biology and Water Institute, University of Waterloo, 200 University Ave. West, Waterloo, Ontario N2L 3G1, Canada
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