Transfer of marine mercury to mountain lakes

Stocking is a worldwide activity on geographical and historical scales. The rate of non-native fish introductions have more than doubled over the last decades yet the effect on natural ecosystems, in the scope of biologically mediated transport and biomagnification of Hg and Hg-isotopes, is unknown....

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Bibliographic Details
Published in:Scientific reports 2017-10, Vol.7 (1), p.12719-12, Article 12719
Main Authors: Hansson, Sophia V., Sonke, Jeroen, Galop, Didier, Bareille, Gilles, Jean, Séverine, Le Roux, Gaël
Format: Article
Language:English
Subjects:
140/125
704/158/2178
704/172/4081
704/47/4112
Aquaculture
Aquatic ecosystems
Biological magnification
Biota
Ecology, environment
Ecosystem assessment
Environmental Sciences
Fish
Fish farms
Fish feeds
Freshwater ecosystems
Freshwater environments
Freshwater lakes
Geochemistry
High-altitude environments
Humanities and Social Sciences
Isotopes
Lakes
Life Sciences
Marine ecosystems
Mercury
Mountain lakes
multidisciplinary
Pollution sources
Salmo trutta
Scales
Science
Science (multidisciplinary)
Stable isotopes
Stocking
Trophic levels
Trout
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Summary:Stocking is a worldwide activity on geographical and historical scales. The rate of non-native fish introductions have more than doubled over the last decades yet the effect on natural ecosystems, in the scope of biologically mediated transport and biomagnification of Hg and Hg-isotopes, is unknown. Using geochemistry (THg) and stable isotopes (N, Sr and Hg), we evaluate natal origin and trophic position of brown trout ( Salmo trutta fario ), as well as mercury biomagnification trends and potential pollution sources to three high-altitude lakes. Farmed trout show Hg-isotope signatures similar to marine biota whereas wild trout shows Hg-isotope signatures typical of fresh water lakes. Stocked trout initially show Hg-isotope signatures similar to marine biota. As the stocked trout age and shifts diet to a higher trophic level, THg concentrations increase and the marine Hg isotope signatures, induced via farm fish feed, shift to locally produced MeHg with lower δ 202 Hg and higher Δ 199 Hg. We conclude that stocking acts a humanly induced biovector that transfers marine Hg to freshwater ecosystems, which is seen in the Hg-isotopic signature up to five years after stocking events occurred. This points to the need of further investigations of the role of stocking in MeHg exposure to freshwater ecosystems.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-017-13001-2