A microbial ecosystem beneath the West Antarctic ice sheet

Journal name:
Nature
Volume:
512,
Pages:
310–313
Date published:
DOI:
doi:10.1038/nature13667
Received
Accepted
Published online

Liquid water has been known to occur beneath the Antarctic ice sheet for more than 40 years1, but only recently have these subglacial aqueous environments been recognized as microbial ecosystems that may influence biogeochemical transformations on a global scale2, 3, 4. Here we present the first geomicrobiological description of water and surficial sediments obtained from direct sampling of a subglacial Antarctic lake. Subglacial Lake Whillans (SLW) lies beneath approximately 800 m of ice on the lower portion of the Whillans Ice Stream (WIS) in West Antarctica and is part of an extensive and evolving subglacial drainage network5. The water column of SLW contained metabolically active microorganisms and was derived primarily from glacial ice melt with solute sources from lithogenic weathering and a minor seawater component. Heterotrophic and autotrophic production data together with small subunit ribosomal RNA gene sequencing and biogeochemical data indicate that SLW is a chemosynthetically driven ecosystem inhabited by a diverse assemblage of bacteria and archaea. Our results confirm that aquatic environments beneath the Antarctic ice sheet support viable microbial ecosystems, corroborating previous reports suggesting that they contain globally relevant pools of carbon and microbes2, 4 that can mobilize elements from the lithosphere6 and influence Southern Ocean geochemical and biological systems7.

At a glance

Figures

  1. Locator map of the WIS and SLW.
    Figure 1: Locator map of the WIS and SLW.

    The yellow box and star indicate the general location of the lake and the drill site; maximum extent of SLW and other lakes28 under the ice stream are shaded in blue; predicted subglacial water flowpaths through SLW and other subglacial lakes are represented by blue lines with arrows; the black line denotes the ice-sheet grounding line at the edge of the Ross Ice Shelf29. Inset (expanded from area in yellow box) shows details of SLW with both maximum (solid blue line) and minimum lake extent (shaded blue area), hydropotential contours (white isolines; 25 kPa interval), and drill site (yellow star; 84.240° S 153.694° W). Background imagery is MODIS MOA30.

  2. Phylogenetic analysis of SSU gene sequences obtained from the SLW water column, surficial sediment (0-2 cm) and drilling water.
    Figure 2: Phylogenetic analysis of SSU gene sequences obtained from the SLW water column, surficial sediment (0–2 cm) and drilling water.

    a, Cluster analysis of the microbial phylogenetic structure in the samples (top) and the relative abundance of bacterial and archaeal phyla in the water and sediment samples (bottom). The Proteobacteria were split into classes for greater detail. The asterisk indicates statistical significance (analysis of molecular variance, AMOVA, P value < 0.001). b, Phylogenetic analysis of bacterial and archaeal OTUs abundant in the SLW water column and sediments. The accession numbers of nearest neighbours and reference taxa are listed parenthetically. Bootstrap values are shown at the nodes. SLW phylotypes are bolded and followed by the percentage each represented in the water column (blue) and sediment (red) libraries. The scale bar indicates the number of nucleotide substitutions per position.

  3. Morphological diversity of microbial cells in the SLW water column.
    Figure 3: Morphological diversity of microbial cells in the SLW water column.

    a, Epifluorescence micrograph showing a variety of cell morphotypes, which was confirmed by scanning electron microscopy (SEM; bd). The yellow arrows in the SEM images indicate cells with rod (b), curved rod (c) and coccoid (d) morphologies. Scale bar, 2 μm.

Tables

  1. Crustal and seawater components to SLW waters
    Extended Data Table 1: Crustal and seawater components to SLW waters
  2. Summary of parameters for the SLW SSU gene sequence data
    Extended Data Table 2: Summary of parameters for the SLW SSU gene sequence data

Accession codes

Primary accessions

Sequence Read Archive

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Author information

Affiliations

  1. Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, USA

    • Brent C. Christner &
    • Amanda M. Achberger
  2. Department of Land Resources and Environmental Science, Montana State University, Bozeman, Montana 59717, USA

    • John C. Priscu,
    • Alexander B. Michaud &
    • Trista J. Vick-Majors
  3. Institute for the Dynamics of Environmental Processes – CNR, Venice, and Department of Environmental Sciences, Informatics and Statistics, Ca′Foscari University of Venice, Venice 30123, Italy

    • Carlo Barbante
  4. Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, USA

    • Sasha P. Carter
  5. Physics Department, St Olaf College, Northfield, Minnesota 55057, USA

    • Knut Christianson
  6. Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, USA

    • Jill A. Mikucki
  7. Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth SY23 3DB, UK

    • Andrew C. Mitchell
  8. Department of Earth Science, Montana State University, Bozeman, Montana 59717, USA

    • Mark L. Skidmore
  9. Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, USA.

    • W. P. Adkins
  10. Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania 16802, USA.

    • S. Anandakrishnan
  11. Department of Earth and Planetary Sciences, University of California, Santa Cruz, Santa Cruz, California 95064, USA.

    • G. Barcheck,
    • L. Beem,
    • M. Beitch,
    • R. Bolsey,
    • C. Branecky,
    • A. Fisher,
    • N. Foley,
    • K. D. Mankoff,
    • D. Sampson &
    • S. Tulaczyk
  12. School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287, USA.

    • A. Behar &
    • E. McBryan
  13. Department of Land Resources and Environmental Science, Montana State University, Bozeman, Montana 59717, USA.

    • R. Edwards,
    • S. Kelley &
    • J. Sherve
  14. Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, USA.

    • H. A. Fricker &
    • M. Siegfried
  15. Department of Geology and Environmental Geosciences, Northern Illinois University, DeKalb, Illinois 60115, USA.

    • B. Guthrie,
    • T. Hodson,
    • R. Powell &
    • R. Scherer
  16. Physics Department, St Olaf College, Northfield, Minnesota 55057, USA.

    • R. Jacobel
  17. Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, USA.

    • A. Purcell
  18. Antarctic Research Centre, Victoria University of Wellington, Wellington 6140, New Zealand.

    • Knut Christianson &
    • H. Horgan
  19. Present address: Courant Institute of Mathematical Sciences, New York University, New York, New York 10012, USA (K.C.).

Consortia

  1. the WISSARD Science Team

    • W. P. Adkins,
    • S. Anandakrishnan,
    • G. Barcheck,
    • L. Beem,
    • A. Behar,
    • M. Beitch,
    • R. Bolsey,
    • C. Branecky,
    • R. Edwards,
    • A. Fisher,
    • H. A. Fricker,
    • N. Foley,
    • B. Guthrie,
    • T. Hodson,
    • H. Horgan,
    • R. Jacobel,
    • S. Kelley,
    • K. D. Mankoff,
    • E. McBryan,
    • R. Powell,
    • A. Purcell,
    • D. Sampson,
    • R. Scherer,
    • J. Sherve,
    • M. Siegfried &
    • S. Tulaczyk

Contributions

The manuscript was written by B.C.C. and J.C.P.; A.M.A. generated and analysed the molecular data; C.B., A.C.M. and M.L.S. conducted and interpreted the chemical measurements; S.P.C. and K.C. provided geophysical data; J.A.M. obtained and examined the CTD data; A.B.M. and T.J.V. contributed and analysed physiological and biogeochemical data; M.L.S. conducted and interpreted the isotopic analyses; and T.J.V. provided the micrographs. All authors contributed to the study design and acquisition of samples and/or data.

Competing financial interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to:

The SSU sequence data are deposited in the NCBI SRA database under the accession number SRP041285.

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Supplementary information

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Additional data