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Cable bacteria generate a firewall against euxinia in seasonally hypoxic basins

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  • Dorina Seitaj, Royal Netherlands Inst Sea Res NIOZ Yerseke, Dept Ecosyst Studies
  • ,
  • Regina Schauer
  • ,
  • Fatimah Sulu-Gambari, Utrecht University, Danmark
  • Silvia Hidalgo-Martinez, Royal Netherlands Inst Sea Res NIOZ Yerseke, Dept Ecosyst Studies, Danmark
  • Sairah Y. Malkin, Vrije Univ Brussel, Vrije University of Brussels, Dept Analyt Environm & Geochem
  • ,
  • Laurine D. W. Burdorf, Royal Netherlands Inst Sea Res NIOZ Yerseke, Dept Ecosyst Studies, Danmark
  • Caroline P. Slomp, Utrecht University
  • ,
  • Filip J. R. Meysman, Vrije Univ Brussel, Vrije University of Brussels, Dept Analyt Environm & Geochem

Seasonal oxygen depletion (hypoxia) in coastal bottom waters can lead to the release and persistence of free sulfide (euxinia), which is highly detrimental to marine life. Although coastal hypoxia is relatively common, reports of euxinia are less frequent, which suggests that certain environmental controls can delay the onset of euxinia. However, these controls and their prevalence are poorly understood. Here we present field observations from a seasonally hypoxic marine basin (Grevelingen, The Netherlands), which suggest that the activity of cable bacteria, a recently discovered group of sulfur-oxidizing microorganisms inducing long-distance electron transport, can delay the onset of euxinia in coastal waters. Our results reveal a remarkable seasonal succession of sulfur cycling pathways, which was observed over multiple years. Cable bacteria dominate the sediment geochemistry in winter, whereas, after the summer hypoxia, Beggiatoaceae mats colonize the sediment. The specific electrogenic metabolism of cable bacteria generates a large buffer of sedimentary iron oxides before the onset of summer hypoxia, which captures free sulfide in the surface sediment, thus likely preventing the development of bottom water euxinia. As cable bacteria are present in many seasonally hypoxic systems, this euxinia-preventing firewall mechanism could be widely active, and may explain why euxinia is relatively infrequently observed in the coastal ocean.

OriginalsprogEngelsk
TidsskriftProceedings of the National Academy of Sciences of the United States of America
Vol/bind112
Nummer43
Sider (fra-til)13278-13283
Antal sider6
ISSN0027-8424
DOI
StatusUdgivet - 27 okt. 2015

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