Comparing total mercury concentrations of northern Dolly Varden, Salvelinus malma malma, in two Canadian Arctic rivers 1986–1988 and 2011–2013

• Published in: Polar biology 2019-05, Vol.42 (5), p.865-876
• Main Authors: Tran, L., Reist, J. D., Gallagher, C. P., Power, M.
• Format: Article
• Language: English
• Subjects: Aquatic environment; Bioaccumulation; Biomedical and Life Sciences; Climate; Climate change; Ecology; Fish; Fishes; Life Sciences; Mercury; Mercury (metal); Microbiology; Oceanography; Original Paper; Plant Sciences; Rivers; Salvelinus malma; Temporal variations; Zoology
• ISSN: 0722-4060; 1432-2056
• DOI: 10.1007/s00300-019-02476-6

Given the importance of anadromous Northern Dolly Varden as a consumption staple for northern residents and the climate- and development-related impacts on total mercury (THg) concentrations, temporal changes in northern Dolly Varden THg concentrations were assessed between historical (1986–1988) and contemporary (2011–2013) periods from two rivers in the north-western Canadian Arctic. In the Rat River, mean THg changed from 79 ± 42 ng/g ww in 1986–1988 to 109 ± 44 ng/g ww in 2011–2013, while in the Firth River, THg changed from 126 ± 45 ng/g ww in 1986–1988 to 178 ± 47 ng/g ww in 2011–2012. Length adjusted values indicated increases in the Firth River were driven by the increased size of fish, but increases in the Rat River were not. After factoring in size, δ 13 C and δ 15 N, [THg] was found to be most influenced over time by fish size, but also significantly modified by temporal period and foodweb position. Relationships between log[THg] versus fork-length and log[THg] versus δ 13 C have remained constant over time in the Rat River, but not in the Firth River, while relationships between log[THg] versus δ 15 N have remained constant in the Firth River, but not in the Rat River. Changes in the significance and the slope of the relationships relating δ 13 C and δ 15 N to log[THg] suggests underlying bioaccumulative processes are temporally variant and will be sensitive to climate-driven changes in the aquatic environments within which fish live and feed.