Small Thaw Ponds: An Unaccounted Source of Methane in the Canadian High Arctic

• Published in: PloS one Vol. 8; no. 11; p. e78204
• Main Authors: Negandhi, Karita, Laurion, Isabelle, Whiticar, Michael J., Galand, Pierre E., Xu, Xiaomei, Lovejoy, Connie
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 13.11.2013; Public Library of Science (PLoS)
• Subjects: Archaea; Arctic Regions; Canada; Carbon 14; Carbon dioxide; Carbon Dioxide - analysis; Carbon dioxide emissions; Carbon sources; Communities; Ecosystems; Gene sequencing; Genes, Archaeal; Global Warming; Isotope ratios; Methane; Methane - analysis; Methane production; Methanobacterium - genetics; Methanogenesis; Methanogenic archaea; Molecular Typing; Next-generation sequencing; Nitrates; Peat; Permafrost; Phylogeny; Polar environments; Ponds; RNA; RNA, Ribosomal, 16S - genetics; rRNA 16S; Sediments; Signatures; Slumping; Stable isotopes; Studies; Thawing; Tundra; Tundra ecology; Tundras; Water Microbiology; Canada; Arctic Regions; California; France; United States > US; Arctic region; Quebec Canada
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0078204

Thawing permafrost in the Canadian Arctic tundra leads to peat erosion and slumping in narrow and shallow runnel ponds that surround more commonly studied polygonal ponds. Here we compared the methane production between runnel and polygonal ponds using stable isotope ratios, ¹⁴C signatures, and investigated potential methanogenic communities through high-throughput sequencing archaeal 16S rRNA genes. We found that runnel ponds had significantly higher methane and carbon dioxide emissions, produced from a slightly larger fraction of old carbon, compared to polygonal ponds. The methane stable isotopic signature indicated production through acetoclastic methanogenesis, but gene signatures from acetoclastic and hydrogenotrophic methanogenic Archaea were detected in both polygonal and runnel ponds. We conclude that runnel ponds represent a source of methane from potentially older C, and that they contain methanogenic communities able to use diverse sources of carbon, increasing the risk of augmented methane release under a warmer climate.