Deep Subseafloor Biogeochemical Processes and Microbial Populations Potentially Associated with the 2011 Tohoku-oki Earthquake at the Japan Trench Accretionary Wedge (IODP Expedition 343)

Shinsuke Kawagucci, Sanae Sakai, Eiji Tasumi, Miho Hirai, Yoshihiro Takaki, Takuro Nunoura, Masafumi Saitoh, Yuichiro Ueno, Naohiro Yoshida, Takazo Shibuya, James Clifford Sample, Tomoyo Okumura, Ken Takai

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Post-mega-earthquake geochemical and microbiological properties in subseafloor sediments of the Japan Trench accretionary wedge were investigated using core samples from Hole C0019E, which was drilled down to 851 m below seafloor (mbsf) at a water depth of 6,890 m. Methane was abundant throughout accretionary prism sediments; however, its concentration decreased close to the plate boundary decollement. Methane isotope systematics indicated a biogenic origin. The content of molecular hydrogen (H2) was low throughout core samples, but markedly increased at specific depths that were close to potential faults predicted by logging-while-drilling analyses. Based on isotopic systematics, H2 appeared to have been abundantly produced via a low-temperature interaction between pore water and the fresh surface of crushed rock induced by earthquakes. Subseafloor microbial cell density remained constant at approximately 105 cells mL–1. Amplicon sequences revealed that predominant members at the phylum level were common throughout the units tested, which also included members frequently found in anoxic subseafloor sediments. Metabolic potential assays using radioactive isotopes as tracers revealed homoacetogenic activity in H2-enriched core samples collected near the fault. Furthermore, homoacetogenic bacteria, including Acetobacterium carbinolicum, were isolated from similar samples. Therefore, post-earthquake subseafloor microbial communities in the Japan Trench accretionary prism appear to be episodically dominated by homoacetogenic populations and potentially function due to the earthquake-induced low-temperature generation of H2. These post-earthquake microbial communities may eventually return to the steady-state communities dominated by oligotrophic heterotrophs and hydrogenotrophic and methylotrophic methanogens that are dependent on refractory organic matter in the sediment.

Original languageEnglish (US)
Article numberME22108
JournalMicrobes and Environments
Volume38
Issue number2
DOIs
StatePublished - 2023
Externally publishedYes

Keywords

  • Integrated Ocean Drilling Program (IODP) Expedition 343
  • Japan Trench Fast Drilling Project (JFAST)
  • acetogenesis
  • coseismic fluid
  • methanogenesis

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Soil Science
  • Plant Science

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