Abstract

Dietary uptake is a key step in conveying both toxic mercury (Hg; particularly as highly bioavailable methylmercury, MeHg) and essential dietary biochemicals, such as polyunsaturated fatty acids (PUFA), across trophic levels within aquatic food webs. Using stable isotopes and fatty acids we evaluated the role of food sources in size-fractioned plankton and littoral macroinvertebrates for the bioaccumulation of total Hg and MeHg in six oligotrophic and one mesotrophic Swedish lakes with differing concentrations of dissolved organic carbon (DOC). We found that the consumption of both algal and terrestrial diets (assessed by PUFA and long-chain saturated fatty acids, respectively) predicted >66% of the Hg concentration variability in meso- (100-500 mu m) and macrozooplankton (>500 mu m) in oligotrophic lakes. In the mesotrophic lake, total Hg bioaccumulation in higher trophic level biota, carnivorous macroinvertebrates was also significantly related to terrestrial diet sources (R-2 = 0.65, p < 0.01). However, lake pH and DOC correlated to total Hg bioaccumulation and bioconcentration across all lakes, suggesting the consumption of different diet sources is mediated by the influence of lake characteristics. This field study reveals that using dietary biomarkers (stable isotopes and fatty acids) together with the physico-chemical lake parameters pH and nutrients together improve our ability to predict Hg bioaccumulation in aquatic food webs. Fatty acids used as dietary biomarkers provide correlative evidence of specific diet source retention in consumers and their effect on Hg bioaccumulation, while pH and nutrients are the underlying physico-chemical lake parameters controlling differences in Hg bioaccumulation between lakes. (C) 2019 Elsevier B.V. All rights reserved.

Keywords

Mercury bioaccumulation; Dissolved organic carbon; Fatty acids; Stable isotopes; Plankton; Macroinvertebrates

Published in

Science of the Total Environment
2019, Volume: 669, pages: 821-832
Publisher: ELSEVIER SCIENCE BV

SLU Authors

• Wu, Pianpian

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

• Åkerblom, Staffan

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    
  • Statistics Sweden (SCB)

• Sonesten, Lars

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

• Bishop, Kevin

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

Ensure healthy lives and promote well-being for all at all ages


UKÄ Subject classification

Environmental Sciences
Ecology


Publication identifier

DOI: https://doi.org/10.1016/j.scitotenv.2019.03.171

Permanent link to this page (URI)

https://res.slu.se/id/publ/99781