Presence of oxygen and aerobic communities from sea floor to basement in deep-sea sediments
Date of Original Version
The depth of oxygen penetration into marine sediments differs considerably from one region to another. In areas with high rates of microbial respiration, O 2 penetrates only millimetres to centimetres into the sediments, but active anaerobic microbial communities are present in sediments hundreds of metres or more below the sea floor. In areas with low sedimentary respiration, O 2 penetrates much deeper but the depth to which microbial communities persist was previously unknown. The sediments underlying the South Pacific Gyre exhibit extremely low areal rates of respiration. Here we show that, in this region, microbial cells and aerobic respiration persist through the entire sediment sequence to depths of at least 75 metres below sea floor. Based on the Redfield stoichiometry of dissolved O 2 and nitrate, we suggest that net aerobic respiration in these sediments is coupled to oxidation of marine organic matter. We identify a relationship of O 2 penetration depth to sedimentation rate and sediment thickness. Extrapolating this relationship, we suggest that oxygen and aerobic communities may occur throughout the entire sediment sequence in 15-44% of the Pacific and 9-37% of the global sea floor. Subduction of the sediment and basalt from these regions is a source of oxidized material to the mantle.
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D'hondt, Steven, Fumio Inagaki, Carlos A. Zarikian, Lewis J. Abrams, Nathalie Dubois, Tim Engelhardt, Helen Evans, Timothy Ferdelman, Britta Gribsholt, Robert N. Harris, Bryce W. Hoppie, Jung Ho Hyun, Jens Kallmeyer, Jinwook Kim, Jill E. Lynch, Claire C. Mckinley, Satoshi Mitsunobu, Yuki Morono, Richard W. Murray, Robert Pockalny, Justine Sauvage, Takaya Shimono, Fumito Shiraishi, David C. Smith, Christopher E. Smith-Duque, Arthur J. Spivack, Bjorn O. Steinsbu, Yohey Suzuki, Michal Szpak, Laurent Toffin, Goichiro Uramoto, Yasuhiko T. Yamaguchi, Guo Liang Zhang, Xiao Hua Zhang, and Wiebke Ziebis. "Presence of oxygen and aerobic communities from sea floor to basement in deep-sea sediments." Nature Geoscience 8, 4 (2015). doi: 10.1038/ngeo2387.