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Diet influences on growth and mercury concentrations of two salmonid species from lakes in the eastern Canadian Arctic.

https://arctichealth.org/en/permalink/ahliterature304422
Source
Environ Pollut. 2021 Jan 01; 268(Pt B):115820
Publication Type
Journal Article
Date
Jan-01-2021
Author
John Chételat
Yueting Shao
Murray C Richardson
Gwyneth A MacMillan
Marc Amyot
Paul E Drevnick
Hardeep Gill
Günter Köck
Derek C G Muir
Author Affiliation
Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, ON, K1A 0H3, Canada. Electronic address: john.chetelat@canada.ca.
Source
Environ Pollut. 2021 Jan 01; 268(Pt B):115820
Date
Jan-01-2021
Language
English
Publication Type
Journal Article
Keywords
Animals
Arctic Regions
Canada
Diet
Environmental monitoring
Lakes
Mercury - analysis
Salmonidae
Water Pollutants, Chemical - analysis
Abstract
Diet, age, and growth rate influences on fish mercury concentrations were investigated for Arctic char (Salvelinus alpinus) and brook trout (Salvelinus fontinalis) in lakes of the eastern Canadian Arctic. We hypothesized that faster-growing fish have lower mercury concentrations because of growth dilution, a process whereby more efficient growth dilutes a fish's mercury burden. Using datasets of 57 brook trout and 133 Arctic char, linear regression modelling showed fish age and diet indices were the dominant explanatory variables of muscle mercury concentrations for both species. Faster-growing fish (based on length-at-age) fed at a higher trophic position, and as a result, their mercury concentrations were not lower than slower-growing fish. Muscle RNA/DNA ratios were used as a physiological indicator of short-term growth rate (days to weeks). Slower growth of Arctic char, inferred from RNA/DNA ratios, was found in winter versus summer and in polar desert versus tundra lakes, but RNA/DNA ratio was (at best) a weak predictor of fish mercury concentration. Net effects of diet and age on mercury concentration were greater than any potential offset by biomass dilution in faster-growing fish. In these resource-poor Arctic lakes, faster growth was associated with feeding at a higher trophic position, likely due to greater caloric (and mercury) intake, rather than growth efficiency.
PubMed ID
33120140 View in PubMed
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High Methylmercury in Arctic and Subarctic Ponds is Related to Nutrient Levels in the Warming Eastern Canadian Arctic.

https://arctichealth.org/en/permalink/ahliterature263333
Source
Environ Sci Technol. 2015 Jun 12;
Publication Type
Article
Date
Jun-12-2015
Author
Gwyneth A MacMillan
Catherine Girard
John Chételat
Isabelle Laurion
Marc Amyot
Source
Environ Sci Technol. 2015 Jun 12;
Date
Jun-12-2015
Language
English
Publication Type
Article
Abstract
Permafrost thaw ponds are ubiquitous in the eastern Canadian Arctic, yet little information exists on their potential as sources of methylmercury (MeHg) to freshwaters. They are microbially active and conducive to methylation of inorganic mercury, and are also affected by Arctic warming. This multiyear study investigated thaw ponds in a discontinuous permafrost region in the Subarctic taiga (Kuujjuarapik-Whapmagoostui, QC) and a continuous permafrost region in the Arctic tundra (Bylot Island, NU). MeHg concentrations in thaw ponds were well above levels measured in most freshwater ecosystems in the Canadian Arctic (>0.1 ng L(-1)). On Bylot, ice-wedge trough ponds showed significantly higher MeHg (0.3-2.2 ng L(-1)) than polygonal ponds (0.1-0.3 ng L(-1)) or lakes (
PubMed ID
26030209 View in PubMed
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The ratio of methylmercury to dissolved organic carbon in water explains methylmercury bioaccumulation across a latitudinal gradient from north-temperate to Arctic lakes.

https://arctichealth.org/en/permalink/ahliterature287178
Source
Environ Sci Technol. 2017 Nov 25;
Publication Type
Article
Date
Nov-25-2017
Author
John Chételat
Murray Richardson
Gwyneth A MacMillan
Marc Amyot
Alexandre J Poulain
Source
Environ Sci Technol. 2017 Nov 25;
Date
Nov-25-2017
Language
English
Publication Type
Article
Abstract
We investigated monomethylmercury (MMHg) bioaccumulation in lakes across a 30? latitudinal gradient in eastern Canada to test the hypothesis that climate-related environmental conditions affect the sensitivity of Arctic lakes to atmospheric mercury contamination. Aquatic invertebrates (chironomid larvae, zooplankton) provided indicators of MMHg bioaccumulation near the base of benthic and planktonic food chains. In step with published data showing latitudinal declines in atmospheric mercury deposition in Canada, we observed lower total mercury concentrations in water and sediment of higher latitude lakes. Despite latitudinal declines of inorganic mercury exposure, MMHg bioaccumulation in aquatic invertebrates did not concomitantly decline. Arctic lakes with greater MMHg in aquatic invertebrates either had: (1) higher water MMHg concentrations (reflecting ecosystem MMHg production) or (2) low water concentrations of MMHg, DOC, chlorophyll and total nitrogen (reflecting lake sensitivity). The MMHg:DOC ratio of surface water was a strong predictor of lake sensitivity to mercury contamination. Bioaccumulation factors for biofilms and seston in Arctic lakes showed more efficient uptake of MMHg in low DOC systems. Environmental conditions associated with low biological production in Arctic lakes and their watersheds increased the sensitivity of lakes to MMHg.
PubMed ID
29172471 View in PubMed
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