Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 15, issue 21
Biogeosciences, 15, 6519-6536, 2018
https://doi.org/10.5194/bg-15-6519-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Biogeosciences, 15, 6519-6536, 2018
https://doi.org/10.5194/bg-15-6519-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 06 Nov 2018

Research article | 06 Nov 2018

Predominance of methanogens over methanotrophs in rewetted fens characterized by high methane emissions

Xi Wen1,14, Viktoria Unger2, Gerald Jurasinski2, Franziska Koebsch2, Fabian Horn1, Gregor Rehder3, Torsten Sachs4, Dominik Zak5,6, Gunnar Lischeid7,8, Klaus-Holger Knorr9, Michael E. Böttcher10, Matthias Winkel1,11, Paul L. E. Bodelier12, and Susanne Liebner1,13 Xi Wen et al.
  • 1Section 5.3 Geomicrobiology, GFZ German Research Centre for Geosciences, Helmholtz Centre Potsdam, Telegrafenberg, 14473 Potsdam, Germany
  • 2Landscape Ecology and Site Evaluation, Faculty for Agricultural and Environmental Sciences, Rostock University, 18059 Rostock, Germany
  • 3Department of Marine Chemistry, Leibniz Institute for Baltic Sea Research, 18119 Warnemünde, Germany
  • 4Section 1.4 Remote Sensing, GFZ German Research Centre for Geosciences, Helmholtz Centre Potsdam, Telegrafenberg, 14473 Potsdam, Germany
  • 5Department of Bioscience, Aarhus University, 8600 Silkeborg, Denmark
  • 6Department of Chemical Analytics and Biogeochemistry, Leibniz Institute of Freshwater Ecology and Inland Fisheries, 12587 Berlin, Germany
  • 7Institute of Landscape Hydrology, Leibniz Center for Agricultural Landscape Research, 15374 Münchberg, Germany
  • 8Institute of Earth and Environmental Science, University of Potsdam, 14476 Potsdam, Germany
  • 9Institute of Landscape Ecology, University of Münster, 48149 Münster, Germany
  • 10Geochemistry and Stable Isotope Biogeochemistry, Leibniz Institute for Baltic Sea Research, 18119 Warnemünde, Germany
  • 11Water and Environmental Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, 306 Tanana Loop, Fairbanks, AK 99775, USA
  • 12Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708PB Wageningen, the Netherlands
  • 13University of Potsdam, Institute of Biochemistry and Biology, 14469 Potsdam, Germany
  • 14College of Electrical Engineering, Northwest Minzu University, Lanzhou, 730070, China

Abstract. The rewetting of drained peatlands alters peat geochemistry and often leads to sustained elevated methane emission. Although this methane is produced entirely by microbial activity, the distribution and abundance of methane-cycling microbes in rewetted peatlands, especially in fens, is rarely described. In this study, we compare the community composition and abundance of methane-cycling microbes in relation to peat porewater geochemistry in two rewetted fens in northeastern Germany, a coastal brackish fen and a freshwater riparian fen, with known high methane fluxes. We utilized 16S rRNA high-throughput sequencing and quantitative polymerase chain reaction (qPCR) on 16S rRNA, mcrA, and pmoA genes to determine microbial community composition and the abundance of total bacteria, methanogens, and methanotrophs. Electrical conductivity (EC) was more than 3 times higher in the coastal fen than in the riparian fen, averaging 5.3 and 1.5mS cm−1, respectively. Porewater concentrations of terminal electron acceptors (TEAs) varied within and among the fens. This was also reflected in similarly high intra- and inter-site variations of microbial community composition. Despite these differences in environmental conditions and electron acceptor availability, we found a low abundance of methanotrophs and a high abundance of methanogens, represented in particular by Methanosaetaceae, in both fens. This suggests that rapid (re)establishment of methanogens and slow (re)establishment of methanotrophs contributes to prolonged increased methane emissions following rewetting.

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Rewetting drained peatlands may lead to prolonged emission of the greenhouse gas methane, but the underlying factors are not well described. In this study, we found two rewetted fens with known high methane fluxes had a high ratio of microbial methane producers to methane consumers and a low abundance of methane consumers compared to pristine wetlands. We therefore suggest abundances of methane-cycling microbes as potential indicators for prolonged high methane emissions in rewetted peatlands.
Rewetting drained peatlands may lead to prolonged emission of the greenhouse gas methane, but...
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