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Widespread nitrogen fixation in sediments from diverse deep-sea sites of elevated carbon loading

Dekas, Anne E. and Fike, David A. and Chadwick, Grayson L. and Green-Saxena, Abigail and Fortney, Julian and Connon, Stephanie A. and Dawson, Katherine and Orphan, Victoria J. (2018) Widespread nitrogen fixation in sediments from diverse deep-sea sites of elevated carbon loading. Environmental Microbiology, 20 (12). pp. 4281-4296. ISSN 1462-2912.

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Nitrogen fixation, the biological conversion of N_2 to NH_3, is critical to alleviating nitrogen limitation in many marine ecosystems. To date, few measurements exist of N_2 fixation in deep‐sea sediments. Here, we conducted > 400 bottle incubations with sediments from methane seeps, whale falls and background sites off the western coast of the United States from 600 to 2893 m water depth to investigate the potential rates, spatial distribution and biological mediators of benthic N_2 fixation. We found that N2 fixation was widespread, yet heterogeneously distributed with sediment depth at all sites. In some locations, rates exceeded previous measurements by > 10×, and provided up to 30% of the community anabolic growth requirement for nitrogen. Diazotrophic activity appeared to be inhibited by pore water ammonium: N_2 fixation was only observed if incubation ammonium concentrations were ≤ 25 μM, and experimental additions of ammonium reduced diazotrophy. In seep sediments, N_2 fixation was dependent on CH_4 and coincident with sulphate reduction, consistent with previous work showing diazotrophy by microorganisms mediating sulphate‐coupled methane oxidation. However, the pattern of diazotrophy was different in whale‐fall and associated reference sediments, where it was largely unaffected by CH_4, suggesting catabolically different diazotrophs at these sites.

Item Type:Article
Related URLs:
URLURL TypeDescription
Dekas, Anne E.0000-0001-9548-8413
Fike, David A.0000-0003-2848-0328
Chadwick, Grayson L.0000-0003-0700-9350
Green-Saxena, Abigail0000-0002-8502-6589
Dawson, Katherine0000-0001-8856-4609
Orphan, Victoria J.0000-0002-5374-6178
Additional Information:© 2018 John Wiley & Sons. Manuscript received: 05 March 2018. Manuscript revised: 25 June 2018. Manuscript accepted: 25 June 2018. Accepted manuscript online: 02 July 2018. We thank the crew and science parties of R/V Atlantis 15‐68, including Lisa Levin, Alexis Pasulka, Josh Steele, Jeffrey Marlow, Jennifer Glass and Elizabeth Trembath‐Reichert, and of R/V Western Flyer DR204‐208, including Shana Goffredi, Bob Vrijenhoek, Julio Harvey and Lonny Lundsten. We thank members of the Fike Laboratory (Washington University), including Dwight McKay, Stephanie Moore and Jennifer Houghton, as well as Fenfang Wu (California Institute of Technology) for assistance with the IRMS measurements. We thank Nathan Dalleska for assistance with IC measurements in the Caltech Environmental Analysis Centre. We thank Matthew Forbes and Karen Casciotti (Stanford University) for assistance with 15N2 purity measurements. We are grateful to MBARI for logistical support and ship time. Funding was provided by the Gordon and Betty Moore Foundation (GBMF no. 3780 to V. J. O.), the US Department of Energy, Office of Science, Office of Biological and Environmental Research (DE‐SC0003940 and DE‐SC0004949 to V. J. O.), and the National Science Foundation (MCB‐0348492 to V. J. O. and OCE‐1634297 to A. E. D.).
Funding AgencyGrant Number
Gordon and Betty Moore FoundationGBMF3780
Department of Energy (DOE)DE-SC0003940
Department of Energy (DOE)DE-SC0004949
Subject Keywords:Nitrogen fixation, diazotrophy, deep sea, whale fall, methane seep, ANME archaea
Issue or Number:12
Record Number:CaltechAUTHORS:20180703-145300132
Persistent URL:
Official Citation:Dekas, A. E., Fike, D. A., Chadwick, G. L., Green‐Saxena, A. , Fortney, J. , Connon, S. A., Dawson, K. S. and Orphan, V. J. (2018), Widespread nitrogen fixation in sediments from diverse deep‐sea sites of elevated carbon loading. Environ Microbiol, 20: 4281-4296. doi:10.1111/1462-2920.14342
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:87541
Deposited By: George Porter
Deposited On:05 Jul 2018 13:54
Last Modified:03 Oct 2019 19:57

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