Terrestrial Dissolved Organic Matter Mobilized From Eroding Permafrost Controls Microbial Community Composition and Growth in Arctic Coastal Zones

Anders Dalhoff Bruhn*, Colin A. Stedmon, Jérôme Comte, Atsushi Matsuoka, Niek Jesse Speetjens, George Tanski, Jorien E. Vonk, Johanna Sjöstedt

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Climate warming is accelerating erosion along permafrost-dominated Arctic coasts. This results in the additional supply of organic matter (OM) and nutrients into the coastal zone. In this study we investigate the impact of coastal erosion on the marine microbial community composition and growth rates in the coastal Beaufort Sea. Dissolved organic matter (DOM) derived from three representative glacial deposit types (fluvial, lacustrine, and moraine) along the Yukon coastal plain, Canada, were used as substrate to cultivate marine bacteria using a chemostat setup. Our results show that DOM composition (inferred from UV-Visible spectroscopy) and biodegradability (inferred from DOC concentration, bacterial production and respiration) significantly differ between the three glacial deposit types. DOM derived from fluvial and moraine types show clear terrestrial characteristics with low aromaticity (Sr: 0.63 ± 0.02 and SUVA254: 1.65 ± 0.06 L mg C−1 m−1 & Sr: 0.68 ± 0.01 and SUVA254: 1.17 ± 0.06 L mg C−1 m−1, respectively) compared to the lacustrine soil type (Sr: 0.71 ± 0.02 and SUVA254: 2.15 ± 0.05 L mg C−1 m−1). The difference in composition of DOM leads to the development of three different microbial communities. Whereas Alphaproteobacteria dominate in fluvial and lacustrine deposit types (67 and 87% relative abundance, respectively), Gammaproteobacteria is the most abundant class for moraine deposit type (88% relative abundance). Bacterial growth efficiency (BGE) is 66% for DOM from moraine deposit type, while 13 and 28% for DOM from fluvial and lacustrine deposit types, respectively. The three microbial communities therefore differ strongly in their net effect on DOM utilization depending on the eroded landscape type. The high BGE value for moraine-derived DOM is probably caused by a larger proportion of labile colorless DOM. These results indicate that the substrate controls marine microbial community composition and activities in coastal waters. This suggests that biogeochemical changes in the Arctic coastal zone will depend on the DOM character of adjacent deposit types, which determine the speed and extent of DOM mineralization and thereby carbon channeling into the microbial food web. We conclude that marine microbes strongly respond to the input of terrestrial DOM released by coastal erosion and that the landscape type differently influence marine microbes.

Original languageEnglish
Article number640580
Pages (from-to)1-20
Number of pages20
JournalFrontiers in Earth Science
Volume9
Issue numberMarch
DOIs
Publication statusPublished - 25 Mar 2021

Bibliographical note

Funding Information:
We acknowledge colleagues in the EU Horizon 2020 Nunataryuk project (grant no. 773421) who contributed to the sampling and logistics and colleagues at Plateforme d?Analyses G?nomiques (IBIS, Universit? Laval, Quebec City, Canada) for performing the Illumina sequencing. H. Lantuit, M. Fritz, and G. Hugelius are thanked for providing logistical and technical support. We also thank Lea Tolstrup for assistance during the chemostat experiment. Finally we thank the editor and the three reviewers for their valuable comments. Funding. This publication is part of the Nunataryuk project. The project has received funding under the European Union?s Horizon 2020 Research and Innovation Programme under grant agreement no. 773421. Part of this research was supported by Japan Aerospace Exploration Agency (JAXA) Global Change Observation Mission-Climate (GCOM-C) to AM (contract #20RT000350), Independent Research Fund Denmark (9040-00266B) awarded to CS, and by the Swedish Research Council (VR, grant 2015-00188) to JS, and the Natural Sciences and Engineering Research Council of Canada (Discovery program, RGPIN-2020-06874) to JC.

Publisher Copyright:
© Copyright © 2021 Bruhn, Stedmon, Comte, Matsuoka, Speetjens, Tanski, Vonk and Sjöstedt.

Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.

Funding

We acknowledge colleagues in the EU Horizon 2020 Nunataryuk project (grant no. 773421) who contributed to the sampling and logistics and colleagues at Plateforme d?Analyses G?nomiques (IBIS, Universit? Laval, Quebec City, Canada) for performing the Illumina sequencing. H. Lantuit, M. Fritz, and G. Hugelius are thanked for providing logistical and technical support. We also thank Lea Tolstrup for assistance during the chemostat experiment. Finally we thank the editor and the three reviewers for their valuable comments. Funding. This publication is part of the Nunataryuk project. The project has received funding under the European Union?s Horizon 2020 Research and Innovation Programme under grant agreement no. 773421. Part of this research was supported by Japan Aerospace Exploration Agency (JAXA) Global Change Observation Mission-Climate (GCOM-C) to AM (contract #20RT000350), Independent Research Fund Denmark (9040-00266B) awarded to CS, and by the Swedish Research Council (VR, grant 2015-00188) to JS, and the Natural Sciences and Engineering Research Council of Canada (Discovery program, RGPIN-2020-06874) to JC.

FundersFunder number
IBIS
Université Laval
Horizon 2020 Framework Programme
Natural Sciences and Engineering Research Council of CanadaRGPIN-2020-06874
Japan Aerospace Exploration Agency20RT000350
Vetenskapsrådet2015-00188
Horizon 2020773421
Danmarks Frie Forskningsfond9040-00266B

    Keywords

    • Arctic coastal zone
    • chemostat
    • climate change
    • glacial deposits
    • marine microbial community
    • permafrost
    • terrestrial dissolved organic matter

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