title: Novel microbial communities of the Haakon Mosby mud volcano and their role as a methane sink.
abstract: Mud volcanism is an important natural source of the greenhouse gas methane to the hydrosphere and atmosphere. Recent investigations show that the number of active submarine mud volcanoes might be much higher than anticipated (for example, see refs 3-5), and that gas emitted from deep-sea seeps might reach the upper mixed ocean. Unfortunately, global methane emission from active submarine mud volcanoes cannot be quantified because their number and gas release are unknown. It is also unclear how efficiently methane-oxidizing microorganisms remove methane. Here we investigate the methane-emitting Haakon Mosby Mud Volcano (HMMV, Barents Sea, 72 degrees N, 14 degrees 44' E; 1,250 m water depth) to provide quantitative estimates of the in situ composition, distribution and activity of methanotrophs in relation to gas emission. The HMMV hosts three key communities: aerobic methanotrophic bacteria (Methylococcales), anaerobic methanotrophic archaea (ANME-2) thriving below siboglinid tubeworms, and a previously undescribed clade of archaea (ANME-3) associated with bacterial mats. We found that the upward flow of sulphate- and oxygen-free mud volcano fluids restricts the availability of these electron acceptors for methane oxidation, and hence the habitat range of methanotrophs. This mechanism limits the capacity of the microbial methane filter at active marine mud volcanoes to <40% of the total flux.
authors.affiliation: Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany.
authors.forename: Helge
authors.initials: H
authors.lastname: Niemann
authors.forename: Tina
authors.initials: T
authors.lastname: Lösekann
authors.forename: Dirk
authors.initials: D
authors.lastname: de Beer
authors.forename: Marcus
authors.initials: M
authors.lastname: Elvert
authors.forename: Thierry
authors.initials: T
authors.lastname: Nadalig
authors.forename: Katrin
authors.initials: K
authors.lastname: Knittel
authors.forename: Rudolf
authors.initials: R
authors.lastname: Amann
authors.forename: Eberhard J
authors.initials: EJ
authors.lastname: Sauter
authors.forename: Michael
authors.initials: M
authors.lastname: Schlüter
authors.forename: Michael
authors.initials: M
authors.lastname: Klages
authors.forename: Jean Paul
authors.initials: JP
authors.lastname: Foucher
authors.forename: Antje
authors.initials: A
authors.lastname: Boetius
mesh_terms: D001105:Archaea / Q000235:genetics / Q000378:metabolism; D001419:Bacteria / Q000235:genetics / Q000378:metabolism; D019015:Geologic Sediments / Q000382:microbiology*; D008697:Methane / Q000378:metabolism*; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D012623:Seawater / Q000737:chemistry / Q000382:microbiology*; D013431:Sulfates / Q000378:metabolism; D018707:Volcanic Eruptions / Q000032:analysis*
chemical_list: D013431:Sulfates; D008697:Methane