Diversity and commonalities in Antarctic subglacial microbial communities

We now know that groundwater, saturated sediments, and hundreds of subglacial lakes exist below the ice sheets of Antarctica. These environments are among the most inaccessible portions of the cryosphere. The exploration of subglacial habitats requires an interdisciplinary approach that integrates geophysics, advances in drilling technologies and geomicrobiological analyses to further our understanding of the subglacial biosphere. Here we highlight recent findings from two distinct subglacial systems. The first is the Blood Falls ecosystem, an iron-rich, saline feature at the terminus of Taylor Glacier in the McMurdo Dry Valleys, Antarctica that appears to be sourced from a much deeper aquifer. The second is Subglacial Lake Whillans, a fresh water lake under the Whillans Ice Stream in the West Antarctic Ice Sheet that drains into the Ross Sea at its grounding zone. Both of these ecosystems appear to persist independent of photosynthetically derived carbon inputs. Molecular data and biogeochemical measurements indicate chemoautotrophic activity is present in both systems with energy derived in part by cycling iron and sulfur compounds. Collectively these data suggest that despite extended isolation in icy darkness, microbial life persists and thrives below the Antarctic Ice Sheet.