title: Comparison of Archaeal and Bacterial Diversity in Methane Seep Carbonate Nodules and Host Sediments, Eel River Basin and Hydrate Ridge, USA.
abstract: Anaerobic oxidation of methane (AOM) impacts carbon cycling by acting as a methane sink and by sequestering inorganic carbon via AOM-induced carbonate precipitation. These precipitates commonly take the form of carbonate nodules that form within methane seep sediments. The timing and sequence of nodule formation within methane seep sediments are not well understood. Further, the microbial diversity associated with sediment-hosted nodules has not been well characterized and the degree to which nodules reflect the microbial assemblage in surrounding sediments is unknown. Here, we conducted a comparative study of microbial assemblages in methane-derived authigenic carbonate nodules and their host sediments using molecular, mineralogical, and geochemical methods. Analysis of 16S rRNA gene diversity from paired carbonate nodules and sediments revealed that both sample types contained methanotrophic archaea (ANME-1 and ANME-2) and syntrophic sulfate-reducing bacteria (Desulfobacteraceae and Desulfobulbaceae), as well as other microbial community members. The combination of geochemical and molecular data from Eel River Basin and Hydrate Ridge suggested that some nodules formed in situ and captured the local sediment-hosted microbial community, while other nodules may have been translocated or may represent a record of conditions prior to the contemporary environment. Taken together, this comparative analysis offers clues to the formation regimes and mechanisms of sediment-hosted carbonate nodules.
authors.affiliation: Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, FL, 32306, USA. omason@fsu.edu.|Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, 91125, USA. omason@fsu.edu.
authors.forename: Olivia U
authors.initials: OU
authors.lastname: Mason
authors.affiliation: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, 91125, USA. dcase@caltech.edu.
authors.forename: David H
authors.initials: DH
authors.lastname: Case
authors.affiliation: Department of Physical and Environmental Sciences, Texas A&M University-Corpus Christi, Corpus Christi, TX, 78412, USA.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Naehr
authors.affiliation: School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA.
authors.forename: Raymond W
authors.initials: RW
authors.lastname: Lee
authors.affiliation: US Geological Survey, Menlo Park, CA, 94025, USA.
authors.forename: Randal B
authors.initials: RB
authors.lastname: Thomas
authors.affiliation: Department of Earth Sciences, University of Minnesota, Minneapolis, MN, 55455, USA.
authors.forename: Jake V
authors.initials: JV
authors.lastname: Bailey
authors.affiliation: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, 91125, USA. vorphan@gps.caltech.edu.
authors.forename: Victoria J
authors.initials: VJ
authors.lastname: Orphan
mesh_terms: D001105:Archaea / Q000502:physiology*; D001419:Bacteria / Q000235:genetics; D018407:Bacterial Physiological Phenomena; D002140:California; D019641:DNA, Archaeal / Q000235:genetics / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D004777:Environment; D019015:Geologic Sediments / Q000382:microbiology*; D008969:Molecular Sequence Data; D009922:Oregon; D010140:Pacific Ocean; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: D019641:DNA, Archaeal; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S
keywords: ANME; Anaerobic methanotrophs; Carbonate concretions; Cold seeps; Sulfate-reducing bacteria