title: Microbial diversity and community structure across environmental gradients in Bransfield Strait, Western Antarctic Peninsula.
abstract: The Southern Ocean is currently subject to intense investigations, mainly related to its importance for global biogeochemical cycles and its alarming rate of warming in response to climate change. Microbes play an essential role in the functioning of this ecosystem and are the main drivers of the biogeochemical cycling of elements. Yet, the diversity and abundance of microorganisms in this system remain poorly studied, in particular with regards to changes along environmental gradients. Here, we used amplicon sequencing of 16S rRNA gene tags using primers covering both Bacteria and Archaea to assess the composition and diversity of the microbial communities from four sampling depths (surface, the maximum and minimum of the oxygen concentration, and near the seafloor) at 10 oceanographic stations located in Bransfield Strait [northwest of the Antarctic Peninsula (AP)] and near the sea ice edge (north of the AP). Samples collected near the seafloor and at the oxygen minimum exhibited a higher diversity than those from the surface and oxygen maximum for both bacterial and archaeal communities. The main taxonomic groups identified below 100 m were Thaumarchaeota, Euryarchaeota and Proteobacteria (Gamma-, Delta-, Beta-, and Alphaproteobacteria), whereas in the mixed layer above 100 m Bacteroidetes and Proteobacteria (mainly Alpha- and Gammaproteobacteria) were found to be dominant. A combination of environmental factors seems to influence the microbial community composition. Our results help to understand how the dynamic seascape of the Southern Ocean shapes the microbial community composition and set a baseline for upcoming studies to evaluate the response of this ecosystem to future changes.
authors.affiliation: Instituto de Microbiologia Professor Paulo de Góes, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil ; Laboratório de Biogeoquímica, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Centro de Ciências da Saúde Rio de Janeiro, Brazil ; Biology Department, Woods Hole Oceanographic Institution Woods Hole, MA, USA.
authors.forename: Camila N
authors.initials: CN
authors.lastname: Signori
authors.affiliation: Biology Department, Woods Hole Oceanographic Institution Woods Hole, MA, USA.
authors.forename: François
authors.initials: F
authors.lastname: Thomas
authors.affiliation: Instituto de Microbiologia Professor Paulo de Góes, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil ; Laboratório de Biogeoquímica, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Centro de Ciências da Saúde Rio de Janeiro, Brazil ; Department of Environmental Change, Linköping University Linköping, Sweden.
authors.forename: Alex
authors.initials: A
authors.lastname: Enrich-Prast
authors.affiliation: Laboratório de Biogeoquímica, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Centro de Ciências da Saúde Rio de Janeiro, Brazil.
authors.forename: Ricardo C G
authors.initials: RC
authors.lastname: Pollery
authors.affiliation: Biology Department, Woods Hole Oceanographic Institution Woods Hole, MA, USA.
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Sievert
keywords: Antarctica; climate change; environmental factors; microbial community structure; microbial oceanography; pyrosequencing