title: Global dispersion and local diversification of the methane seep microbiome.
abstract: Methane seeps are widespread seafloor ecosystems shaped by the emission of gas from seabed reservoirs. The microorganisms inhabiting methane seeps transform the chemical energy in methane to products that sustain rich benthic communities around the gas leaks. Despite the biogeochemical relevance of microbial methane removal at seeps, the global diversity and dispersion of seep microbiota remain unknown. Here we determined the microbial diversity and community structure of 23 globally distributed methane seeps and compared these to the microbial communities of 54 other seafloor ecosystems, including sulfate-methane transition zones, hydrothermal vents, coastal sediments, and deep-sea surface and subsurface sediments. We found that methane seep communities show moderate levels of microbial richness compared with other seafloor ecosystems and harbor distinct bacterial and archaeal taxa with cosmopolitan distribution and key biogeochemical functions. The high relative sequence abundance of ANME (anaerobic methanotrophic archaea), as well as aerobic Methylococcales, sulfate-reducing Desulfobacterales, and sulfide-oxidizing Thiotrichales, matches the most favorable microbial metabolisms at methane seeps in terms of substrate supply and distinguishes the seep microbiome from other seafloor microbiomes. The key functional taxa varied in relative sequence abundance between different seeps due to the environmental factors, sediment depth and seafloor temperature. The degree of endemism of the methane seep microbiome suggests a high local diversification in these heterogeneous but long-lived ecosystems. Our results indicate that the seep microbiome is structured according to metacommunity processes and that few cosmopolitan microbial taxa mediate the bulk of methane oxidation, with global relevance to methane emission in the ocean.
authors.affiliation: HGF MPG Group for Deep Sea Ecology and Technology and Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, D-28359 Bremen, Germany; eruff@mpi-bremen.de.
authors.forename: S Emil
authors.initials: SE
authors.lastname: Ruff
authors.affiliation: College of Earth, Ocean and Environment, University of Delaware, Lewes, DE 19958;
authors.forename: Jennifer F
authors.initials: JF
authors.lastname: Biddle
authors.affiliation: Department of Marine Sciences, University of North Carolina, Chapel Hill, NC 27599-3300;
authors.forename: Andreas P
authors.initials: AP
authors.lastname: Teske
authors.affiliation: Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, D-28359 Bremen, Germany;
authors.forename: Katrin
authors.initials: K
authors.lastname: Knittel
authors.affiliation: HGF MPG Group for Deep Sea Ecology and Technology and Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, D-27570 Bremerhaven, Germany; and Center for Marine Environmental Sciences, University of Bremen, D-28359 Bremen, Germany.
authors.forename: Antje
authors.initials: A
authors.lastname: Boetius
authors.affiliation: HGF MPG Group for Deep Sea Ecology and Technology and.
authors.forename: Alban
authors.identifier: http://orcid.org/0000-0002-3437-4639
authors.initials: A
authors.lastname: Ramette
mesh_terms: D001105:Archaea / Q000145:classification / Q000502:physiology; D044822:Biodiversity; D030541:Databases, Genetic; D020564:Deltaproteobacteria / Q000145:classification / Q000502:physiology; D017753:Ecosystem; D020563:Gammaproteobacteria / Q000145:classification / Q000502:physiology; D019015:Geologic Sediments / Q000382:microbiology*; D060086:Hydrothermal Vents / Q000382:microbiology; D008697:Methane / Q000737:chemistry*; D064307:Microbiota; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology*; D017422:Sequence Analysis, DNA
chemical_list: D012336:RNA, Ribosomal, 16S; D008697:Methane
keywords: ANME; anaerobic methane oxidation; deep-sea seafloor ecosystems; environmental selection; microbial community ecology