Temperature response of denitrification and anaerobic ammonium oxidation rates and microbial community structure in Arctic fjord sediments

• Published in: Environmental Microbiology
• Main Authors: Canion, Andy, Overholt, Will A., Kostka, Joel E., Huettel, Markus, Lavik, Gaute, Kuypers, Marcel M. M.
• Other Authors: BP/Gulf of Mexico Research Initiative, Max Planck Society, National Science Foundation
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2014
• Subjects: Arctic
• Online Access: http://dx.doi.org/10.1111/1462-2920.12593; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2F1462-2920.12593; http://onlinelibrary.wiley.com/wol1/doi/10.1111/1462-2920.12593/fullpdf

Summary The temperature dependency of denitrification and anaerobic ammonium oxidation (anammox) rates from A rctic fjord sediments was investigated in a temperature gradient block incubator for temperatures ranging from −1 to 40°C. Community structure in intact sediments and slurry incubations was determined using Illumina SSU rRNA gene sequencing. The optimal temperature ( T opt ) for denitrification was 25–27°C, whereas anammox rates were optimal at 12–17°C. Both denitrification and anammox exhibited temperature responses consistent with a psychrophilic community, but anammox bacteria may be more specialized for psychrophilic activity. Long‐term (1–2 months) warming experiments indicated that temperature increases of 5–10°C above in situ had little effect on the microbial community structure or the temperature response of denitrification and anammox. Increases of 25°C shifted denitrification temperature responses to mesophilic with concurrent community shifts, and anammox activity was eliminated above 25°C. Additions of low molecular weight organic substrates (acetate and lactate) caused increases in denitrification rates, corroborating the hypothesis that the supply of organic substrates is a more dominant control of respiration rates than low temperature. These results suggest that climate‐related changes in sinking particulate flux will likely alter rates of N removal more rapidly than warming.