Temperature effects on net greenhouse gas production and bacterial communities in arctic thaw ponds.

• Published in: FEMS Microbiology Ecology
• Main Authors: Negandhi, Karita, Laurion, Isabelle, Lovejoy, Connie, Wagner, Dirk
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2016
• Subjects: arctic warming; organic carbon; permafrost; high-throughput tag sequencing; 16S rRNA; methane; carbon dioxide; Arctic; Ice
• Online Access: https://espace.inrs.ca/id/eprint/5706/; https://doi.org/10.1093/femsec/fiw117

One consequence of High Arctic permafrost thawing is the formation of small ponds, which release greenhouse gases (GHG) from stored carbon through microbial activity. Under a climate with higher summer air temperatures and longer ice-free seasons, sediments of shallow ponds are likely to become warmer, which could influence enzyme kinetics or select for less cryophilic microbes. There is little data on the direct temperature effects on GHG production and consumption or on microbial communities’ composition in Arctic ponds. We investigated GHG production over 16 days at 4°C and 9°C in sediments collected from four thaw ponds. Consistent with an enzymatic response, production rates of CO₂ and CH₄ were significantly greater at higher temperatures, with Q₁₀ varying from 1.2 to 2.5. The bacterial community composition from one pond was followed through the incubation by targeting the V6–V8 variable regions of the 16S rRNA gene and 16S rRNA. Several rare taxa detected from rRNA accounted for significant community compositional changes. At the higher temperature, the relative community contribution from Bacteroidetes decreased by 15% with compensating increases in Betaproteobacteria, Alphaproteobacteria, Firmicutes, Acidobacteria, Verrucomicrobia and Actinobacteria. The increase in experimental GHG production accompanied by changes in community indicates an additional factor to consider in sediment environments when evaluating future climate scenarios.