Vertical distribution of microbial communities in a perennially stratified Arctic lake with saline, anoxic bottom waters

• Published in: Scientific Reports
• Main Authors: Comeau, André M., Harding, Tommy, Galand, Pierre E., Vincent, Warwick F., Lovejoy, Connie
• Format: Text
• Language: English
• Published: Nature Publishing Group 2012
• Subjects: Article; Arctic; Arctic Lake; Canada
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3428602; http://www.ncbi.nlm.nih.gov/pubmed/22930670; https://doi.org/10.1038/srep00604

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.