IMIS - Marine Research Groups

Subglacial Lake Whillans (SLW)lies beneath approximately 800m of ice on the lower portion of the Whillans Ice Stream (WIS) in West Antarctica and is part of an extensive and evolving subglacial drainage network. The water column of SLW contained metabolically active microorganisms and was derived primarily from glacial ice melt with solute sources from lithogenic weathering and a minor seawater component. Heterotrophic and autotrophic production data together with small subunit ribosomal RNA gene sequencing and biogeochemical data indicate that SLW is a chemosynthetically driven ecosystem inhabited by a diverse assemblage of bacteria and archaea. Our results confirm that aquatic environments beneath the Antarctic ice sheet support viable microbial ecosystems, corroborating previous reports suggesting that they contain globally relevant pools of carbon and microbes that can mobilize elements from the lithosphere and influence Southern Ocean geochemical and biological systems.
Geographic coverage: Samples were collected from Subglacial Lake Whillans, at the lower portion of the Whillans Ice Stream, West Antarctica. Samples were collected through a 800m borehole created with a clean, hot water drill system.
Taxonomic coverage: Planktonic microbial cells were collected on 0.2, 0.8, 3.0, and 10.0 micron filters and community structure was determined from 16S rRNA gene identities. Microbial community structure was also determined for samples from a shallow sediment core (0-40 cm).
Sampling methods: Water samples were collected and brought to the surface in Niskin bottles. Particulate matter for DNA sequence analyses was collected on 10.0, 3.0, 0.8, and 0.2 micron filters by an in situ filtration unit. Sediment samples were collected and brought to the surface using a shallow sediment multicorer. See Christner, et al 2014 for details.
Quality control: Paired end sequence reads were assembled and quality filtered using the Mothur phylogenetic analysis pipeline (v1.33.2). The sequences were aligned with the SILVA Incremental Aligner47 (SINA v1.2.11; database release 115). The aligned reads were checked for chimaeras using the Uchime algorithm, as implemented within Mothur, and chimaeric sequences were removed from the data. Sequences with >97% SSU rRNA gene sequence similarity were clustered into an OTU and representative sequences for each OTU were chosen for classification using the SILVA database.