Subseafloor sedimentary life in the South Pacific Gyre

The low-productivity South Pacific Gyre (SPG) is Earth's largest oceanic province. Its sediment accumulates extraordinarily slowly (0.1-1 m per million years). This sediment contains a living community that is characterized by very low biomass and very low metabolic activity. At every depth in...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2009-07, Vol.106 (28), p.11651-11656
Main Authors: D'Hondt, Steven, Spivack, Arthur J, Pockalny, Robert, Ferdelman, Timothy G, Fischer, Jan P, Kallmeyer, Jens, Abrams, Lewis J, Smith, David C, Graham, Dennis, Hasiuk, Franciszek, Schrum, Heather, Stancin, Andrea M
Format: Article
Language:English
Subjects:
Animals
Biodiversity
Biological Sciences
Biomass
Carbon
Chlorophylls
Drilling
Earth
Electrons
Energy Metabolism - physiology
Geologic Sediments - microbiology
Gyres
Hydrogen - metabolism
Metabolism
Oceanography
Oceans
Pacific Ocean
Radiolysis
Respiration
Sea water
Sedimentation & deposition
Sediments
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Summary:The low-productivity South Pacific Gyre (SPG) is Earth's largest oceanic province. Its sediment accumulates extraordinarily slowly (0.1-1 m per million years). This sediment contains a living community that is characterized by very low biomass and very low metabolic activity. At every depth in cored SPG sediment, mean cell abundances are 3 to 4 orders of magnitude lower than at the same depths in all previously explored subseafloor communities. The net rate of respiration by the subseafloor sedimentary community at each SPG site is 1 to 3 orders of magnitude lower than the rates at previously explored sites. Because of the low respiration rates and the thinness of the sediment, interstitial waters are oxic throughout the sediment column in most of this region. Consequently, the sedimentary community of the SPG is predominantly aerobic, unlike previously explored subseafloor communities. Generation of H₂ by radiolysis of water is a significant electron-donor source for this community. The per-cell respiration rates of this community are about 2 orders of magnitude higher (in oxidation/reduction equivalents) than in previously explored anaerobic subseafloor communities. Respiration rates and cell concentrations in subseafloor sediment throughout almost half of the world ocean may approach those in SPG sediment.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0811793106