MEPS 601:33-39 (2018)  -  DOI:

Bacterial chemoautotrophic reoxidation in sub-Arctic sediments: a seasonal study in Kobbefjord, Greenland

Diana Vasquez-Cardenas1,*, Lorenz Meire2,3, Heidi L. Sørensen3,4, Ronnie N. Glud3,4, Filip J. R. Meysman1,5, Henricus T. S. Boschker1,5

1Department of Biotechnology, Delft University of Technology, 2629 HZ Delft, The Netherlands
2Royal Netherlands Institute for Sea Research and Utrecht University, 4401 NT Yerseke, The Netherlands
3Greenland Climate Research Centre, Greenland Institute of Natural Resources, 3900 Nuuk, Greenland
4Nordic Centre for Earth Evolution, Department of Biology, University of Southern Denmark, 5230 Odense, Denmark
5Ecosystem Management Research Group, Department of Biology, University of Antwerp, 2610 Wilrijk, Belgium
*Corresponding author:

ABSTRACT: Anoxic mineralization of organic matter releases dissolved inorganic carbon and produces reduced mineralization products. The reoxidation of these reduced compounds is essential for biogeochemical cycling in sediments and is mainly performed by chemoautotrophic microbes, which synthesize new organic carbon by dark CO2 fixation. At present however, the biogeochemical importance of chemoautotrophy in high-latitude sediments is largely unknown. Here, we determine the seasonal variation in sedimentary chemoautotrophic production in Kobbefjord (SW Greenland). Intact sediment cores from the fjord were incubated, and dark CO2 fixation was quantified by combining bacterial phospholipid-derived fatty acid analysis with 13C stable isotope probing (PLFA-SIP). Our results reveal a distinct seasonal cycle in chemoautotrophic activity, which increases after the spring bloom and shows lowest activity in the late winter when the fjord is covered by sea ice. The depth distribution of chemoautotrophic activity also varied seasonally, likely due to seasonal variation in the bioturbation activity of sediment infauna. Although chemoautotrophy rates (0.4 ± 0.2 mmol C m-2 d-1) were in the low range for coastal sediments, they are comparable to those from intertidal sandflats and brackish tropical lagoons, and scale with the sulfide production through sulfate reduction in the fjord. Chemoautotrophic production in these fjord sediments thus appears to be mainly driven by sulfide oxidation and can re-fix 4% of the CO2 produced by mineralization.

KEY WORDS: Dark carbon fixation · Chemolithoautotrophy · Fatty acids · Stable isotope labeling · PLFA-SIP

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Cite this article as: Vasquez-Cardenas D, Meire L, Sørensen HL, Glud RN, Meysman FJR, Boschker HTS (2018) Bacterial chemoautotrophic reoxidation in sub-Arctic sediments: a seasonal study in Kobbefjord, Greenland. Mar Ecol Prog Ser 601:33-39.

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