Department Surface Waters - Research and Management

Nutrients and Toxic Metals in Arctic Rivers

A turbid, glacial-influenced river flowing into the Taermiut Fjord in South Greenland


Arctic rivers are important vectors of nutrients and biogeochemical tracers, connecting the catchment to the coastal ocean. However, these rivers can also transport toxic metals - high natural enrichments of potentially toxic metals (e.g. copper, zinc, lead) are found throughout Greenland and the Canadian Arctic. This can present local ecological risks that may be further exacerbated by anthropogenic activity.

This project investigates concentrations of nutrients and toxins in the rivers of Greenland, with a focus on controls of their distributions, their forms and their fluxes. The Arctic is a rapidly changing environment, with increasing ice melt, retreating glaciers, and altered precipitation patterns. Melting permafrost and land use change further alter river conditions.
Therefore, in addition to providing modern constraints on these understudied systems, this project will help to set baseline values to assess future change.

Publications

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      authors => protected'Saboret, G.; Moccetti, C.; Wassenaar, L. I.; Matthews,&n
         bsp;B.; Aquino, N. J.; Janssen, D. J.; Brodersen, J
         .; Schubert, C. J.' (180 chars)
      title => protected'Impact of glaciers on trophic dynamics and polyunsaturated fat accumulation 
         in Southern Greenland Fjord ecosystems' (114 chars)
      journal => protected'Global Change Biology' (21 chars)
      year => protected2025 (integer)
      volume => protected31 (integer)
      issue => protected'1' (1 chars)
      startpage => protected'e70044 (19 pp.)' (15 chars)
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      categories => protected'amino acid isotope; arctic char; fjord; food web; glacier; Greenland; polyun
         saturated fatty acid; trophic position' (114 chars)
      description => protected'The primary production of fjords across the Arctic and Subarctic is undergoi
         ng significant transformations due to the climatically driven retreat of gla
         ciers and ice sheets. However, the implications of these changes for upper t
         rophic levels remain largely unknown. In this study, we employ both bulk and
          compound-specific stable isotope analyses to investigate how shifts at the 
         base of fjord food webs impact the carbon and energy sources of consumers. F
         ocusing on two rapidly changing fjords in Southern Greenland, we used the mi
         gratory Arctic char as an indicator species, sampling populations along envi
         ronmental gradients within the fjords, building upon the assumption that cha
         r populations feed primarily close to their natal stream, thereby integratin
         g a dietary gradient. Our analysis of bulk stable isotopes in Arctic char ti
         ssue confirmed this premise, revealing a consistent change in resource use f
         rom the outer to the inner fjord, which nonetheless served as preferred feed
         ing grounds. Essential amino acid analysis further indicated shifts in carbo
         n and nitrogen sources, consistent with changes in nutrient use near glacier
          inputs characterized by low turbidity and high iron levels. Notably, these 
         changes in the source of primary production were associated with shifts in t
         rophic positions and the transfer of polyunsaturated fatty acids, with Arcti
         c char in glacier-influenced inner fjords feeding at lower trophic level (si
         ze-corrected) and accumulating higher levels of high-quality docosahexaenoic
          acid (DHA). These findings highlight the usefulness of new analytical tools
          in revealing that glacial retreat can substantially alter food web dynamics
         , enhancing both carbon flow and the nutritional quality of fish in fjord ec
         osystems. The two Southern Greenland fjords studied could represent the futu
         re of other fjords, where retreating glaciers become land-terminating and gl
         acial inputs decrease. Our study underscores the critical role of glacier dy
         namics in affecting high...' (2075 chars)
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      doi => protected'10.1111/gcb.70044' (17 chars)
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Impact of glaciers on trophic dynamics and polyunsaturated fat accumulation in Southern Greenland Fjord ecosystems

The primary production of fjords across the Arctic and Subarctic is undergoing significant transformations due to the climatically driven retreat of glaciers and ice sheets. However, the implications of these changes for upper trophic levels remain largely unknown. In this study, we employ both bulk and compound-specific stable isotope analyses to investigate how shifts at the base of fjord food webs impact the carbon and energy sources of consumers. Focusing on two rapidly changing fjords in Southern Greenland, we used the migratory Arctic char as an indicator species, sampling populations along environmental gradients within the fjords, building upon the assumption that char populations feed primarily close to their natal stream, thereby integrating a dietary gradient. Our analysis of bulk stable isotopes in Arctic char tissue confirmed this premise, revealing a consistent change in resource use from the outer to the inner fjord, which nonetheless served as preferred feeding grounds. Essential amino acid analysis further indicated shifts in carbon and nitrogen sources, consistent with changes in nutrient use near glacier inputs characterized by low turbidity and high iron levels. Notably, these changes in the source of primary production were associated with shifts in trophic positions and the transfer of polyunsaturated fatty acids, with Arctic char in glacier-influenced inner fjords feeding at lower trophic level (size-corrected) and accumulating higher levels of high-quality docosahexaenoic acid (DHA). These findings highlight the usefulness of new analytical tools in revealing that glacial retreat can substantially alter food web dynamics, enhancing both carbon flow and the nutritional quality of fish in fjord ecosystems. The two Southern Greenland fjords studied could represent the future of other fjords, where retreating glaciers become land-terminating and glacial inputs decrease. Our study underscores the critical role of glacier dynamics in affecting high-level consumers, such as salmonids, with implications for fjords globally.
Saboret, G.; Moccetti, C.; Wassenaar, L. I.; Matthews, B.; Aquino, N. J.; Janssen, D. J.; Brodersen, J.; Schubert, C. J. (2025) Impact of glaciers on trophic dynamics and polyunsaturated fat accumulation in Southern Greenland Fjord ecosystems, Global Change Biology, 31(1), e70044 (19 pp.), doi:10.1111/gcb.70044, Institutional Repository

Heavy metals in the rivers of Greenland (Eawag News)

Contact

Dr. David Janssen Tel. +41 58 765 2251 Send Mail

Collaboration

Funding