title: Vertical distribution of microbial communities in a perennially stratified Arctic lake with saline, anoxic bottom waters.
abstract: Meromictic lakes are useful biogeochemical models because of their stratified chemical gradients and separation of redox reactions down the water column. Perennially ice-covered meromictic lakes are particularly stable, with long term constancy in their density profiles. Here we sampled Lake A, a deep meromictic lake at latitude 83°N in High Arctic Canada. Sampling was before (May) and after (August) an unusual ice-out event during the warm 2008 summer. We determined the bacterial and archaeal community composition by high-throughput 16S rRNA gene tag-pyrosequencing. Both prokaryote communities were stratified by depth and the Bacteria differed between dates, indicating locally driven selection processes. We matched taxa to known taxon-specific biogeochemical functions and found a close correspondence between the depth of functional specialists and chemical gradients. These results indicate a rich microbial diversity despite the extreme location, with pronounced vertical structure in taxonomic and potential functional composition, and with community shifts during ice-out.
authors.affiliation: Québec-Océan and Département de Biologie, Université Laval, Québec, QC, Canada. andre.comeau@ibis.ulaval.ca
authors.forename: André M
authors.initials: AM
authors.lastname: Comeau
authors.forename: Tommy
authors.initials: T
authors.lastname: Harding
authors.forename: Pierre E
authors.initials: PE
authors.lastname: Galand
authors.forename: Warwick F
authors.initials: WF
authors.lastname: Vincent
authors.forename: Connie
authors.initials: C
authors.lastname: Lovejoy
mesh_terms: D001105:Archaea / Q000145:classification / Q000235:genetics*; D001110:Arctic Regions; D001419:Bacteria / Q000145:classification / Q000235:genetics*; D044822:Biodiversity; D002170:Canada; D017753:Ecosystem; D005843:Geography; D060106:Lakes / Q000737:chemistry / Q000382:microbiology*; D010100:Oxygen; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D054712:Salinity; D014871:Water Microbiology
chemical_list: D012336:RNA, Ribosomal, 16S; D010100:Oxygen