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Research article - Peer-reviewed, 2017

Terrestrial discharges mediate trophic shifts and enhance methylmercury accumulation in estuarine biota

Jonsson, Sofi; Andersson, Agneta; Nilsson, Mats B.; Skyllberg, Ulf; Lundberg, Erik; Schaefer, Jeffra K.; Akerblom, Staffan; Bjorn, Erik


The input of mercury (Hg) to ecosystems is estimated to have increased two-to fivefold during the industrial era, and Hg accumulates in aquatic biota as neurotoxic methylmercury (MeHg). Escalating anthropogenic land use and climate change are expected to alter the input rates of terrestrial natural organic matter (NOM) and nutrients to aquatic ecosystems. For example, climate change has been projected to induce 10 to 50% runoff increases for large coastal regions globally. A major knowledge gap is the potential effects on MeHg exposure to biota following these ecosystem changes. We monitored the fate of five enriched Hg isotope tracers added to mesocosm scale estuarine model ecosystems subjected to varying loading rates of nutrients and terrestrial NOM. We demonstrate that increased terrestrial NOM input to the pelagic zone can enhance the MeHg bioaccumulation factor in zooplankton by a factor of 2 to 7 by inducing a shift in the pelagic food web from autotrophic to heterotrophic. The terrestrial NOM input also enhanced the retention of MeHg in the water column by up to a factor of 2, resulting in further increased MeHg exposure to pelagic biota. Using mercury mass balance calculations, we predict that MeHg concentration in zooplankton can increase by a factor of 3 to 6 in coastal areas following scenarios with 15 to 30% increased terrestrial runoff. The results demonstrate the importance of incorporating the impact of climate-induced changes in food web structure on MeHg bioaccumulation in future biogeochemical cycling models and risk assessments of Hg.

Published in

Science Advances
2017, volume: 3, number: 1, article number: e1601239

Authors' information

Jonsson, Sofi
Umeå University
Andersson, Agneta
Umeå University
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Lundberg, Erik
Umeå University
Schaefer, Jeffra K.
Rutgers University (State University of New Jersey)
Åkerblom, Staffan
Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment
Björn, Erik
Umeå University

Sustainable Development Goals

SDG15 Life on land
SDG14 Life below water
SDG13 Climate action

UKÄ Subject classification

Environmental Sciences

Publication Identifiers


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