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Aerobic production of methane in the sea

Nature Geoscience volume 1, pages 473478 (2008) | Download Citation

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Abstract

Methane is a potent greenhouse gas that has contributed approximately 20% to the Earth’s warming since pre-industrial times. The world’s oceans are an important source of methane, comprising 1–4% of annual global emissions. But despite its global significance, oceanic methane production is poorly understood. In particular, methane concentrations in the surface waters of most of the world’s oceans are supersaturated with respect to atmospheric concentrations, but the origin of this methane, which has been thought to be produced exclusively in anaerobic environments, is not known. Here, we measure methane production in seawater samples amended with methylphosphonate, an organic, phosphorus-containing compound. We show that methane is produced aerobically as a by-product of methylphosphonate decomposition in phosphate-stressed waters. Methylphosphonate decomposition, and thus methane production, may be enhanced by the activity of nitrogen-fixing microorganisms. We suggest that aerobic marine methane production will be sensitive to the changes in water-column stratification and nutrient limitation that are likely to result from greenhouse-gas-induced ocean warming.

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Acknowledgements

The authors thank J. Dore for advice and assistance with methane determinations, and A. White and R. Letelier for field assistance, expertise and leadership during the August 2007 R/V Kilo Moana BloomER expedition. This research was supported by the Gordon and Betty Moore Foundation and the National Science Foundation and is a contribution from the Center for Microbial Oceanography: Research and Education (C-MORE).

Author information

Affiliations

  1. University of Hawaii, Honolulu, Hawaii 96822, USA

    • David M. Karl
    • , Lucas Beversdorf
    • , Karin M. Björkman
    •  & Matthew J. Church
  2. Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

    • Asuncion Martinez
    •  & Edward F. Delong

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Contributions

D.M.K. formulated the hypothesis, directed the research and wrote the first draft of the manuscript. L.B. and K.B. carried out most of the experiments. E.F.D. and A.M. conducted and analysed the genome database search. All authors contributed to the experimental design, data interpretation and preparation of the final draft of the manuscript.

Corresponding author

Correspondence to David M. Karl.

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DOI

https://doi.org/10.1038/ngeo234

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