title: Bacterial diversity and community composition from seasurface to subseafloor.
abstract: We investigated compositional relationships between bacterial communities in the water column and those in deep-sea sediment at three environmentally distinct Pacific sites (two in the Equatorial Pacific and one in the North Pacific Gyre). Through pyrosequencing of the v4-v6 hypervariable regions of the 16S ribosomal RNA gene, we characterized 450,104 pyrotags representing 29,814 operational taxonomic units (OTUs, 97% similarity). Hierarchical clustering and non-metric multidimensional scaling partition the samples into four broad groups, regardless of geographic location: a photic-zone community, a subphotic community, a shallow sedimentary community and a subseafloor sedimentary community (⩾1.5 meters below seafloor). Abundance-weighted community compositions of water-column samples exhibit a similar trend with depth at all sites, with successive epipelagic, mesopelagic, bathypelagic and abyssopelagic communities. Taxonomic richness is generally highest in the water-column O2 minimum zone and lowest in the subseafloor sediment. OTUs represented by abundant tags in the subseafloor sediment are often present but represented by few tags in the water column, and represented by moderately abundant tags in the shallow sediment. In contrast, OTUs represented by abundant tags in the water are generally absent from the subseafloor sediment. These results are consistent with (i) dispersal of marine sedimentary bacteria via the ocean, and (ii) selection of the subseafloor sedimentary community from within the community present in shallow sediment.
authors.affiliation: Department of Microbiology, The Forsyth Institute, Cambridge, MA, USA.|Harvard School of Dental Medicine, Boston, MA, USA.
authors.forename: Emily A
authors.initials: EA
authors.lastname: Walsh
authors.affiliation: Graduate School of Oceanography, University of Rhode Island, Narragansett Bay Campus, Narragansett, RI, USA.
authors.forename: John B
authors.initials: JB
authors.lastname: Kirkpatrick
authors.affiliation: Department of Environmental Sciences, Roger Williams University, Bristol, RI, USA.
authors.forename: Scott D
authors.initials: SD
authors.lastname: Rutherford
authors.affiliation: Graduate School of Oceanography, University of Rhode Island, Narragansett Bay Campus, Narragansett, RI, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Smith
authors.affiliation: Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA, USA.
authors.forename: Mitchell
authors.initials: M
authors.lastname: Sogin
authors.affiliation: Graduate School of Oceanography, University of Rhode Island, Narragansett Bay Campus, Narragansett, RI, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: D'Hondt
mesh_terms: D001419:Bacteria / Q000235:genetics; D044822:Biodiversity; D002734:Chlorophyll / Q000737:chemistry; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000235:genetics*; D005843:Geography; D019015:Geologic Sediments / Q000382:microbiology*; D009792:Oceans and Seas; D010100:Oxygen / Q000737:chemistry; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D017422:Sequence Analysis, DNA; D014871:Water Microbiology
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D002734:Chlorophyll; D010100:Oxygen