Science Projects: GBASE

Microbe images, and investigator peering into ice hole

GBASE: GeomicroBiology of Antarctic Subglacial Environments

The GBASE project is one of three research components of the WISSARD (Whillans Ice Stream Subglacial Access Research Drilling) integrative initiative that is being funded by the Antarctic Integrated System Science Program of the National Science Foundations's Office of Polar Programs, Antarctic Division.

GBASE will examine distinct, but hydrologically related, subglacial environments using a combination of biogeochemical/ genomic measurements to answer key questions directly relevant to metabolic and phylogenetic biodiversity and the biogeochemical transformation of major nutrients beneath the Whillans Ice Stream.

This research will focus on the lower portion of the Whillans Ice Stream in West Antarctica where two hydraulically connected subglacial environments will be accessed: (1) Subglacial Lake Whillans, and (2) wet subglacial sediments and the aquatic environment near the grounding zone where the West Antarctic Ice Sheet meets the sea. GBASE will collect metagenomic and geochemical samples and examine both the subglacial lakes (i.e. basal ice, bulk water and sediments) and the grounding zone sites. This research will provide important phylogenetic and biogeochemical linkages across ecosystem components.

This five year project incorporates surface geophysical data with borehole and subglacial sampling and measurements. The boreholes will be drilled using a hot water drill that will utilize a large volume microfiltration and UV treatment system to continuously "sterilize" the hot water within the borehole to reduce the number of viable microorganisms originating from the melted snow and ice used as the source water for the hot water drill. This approach will maintain a pristine subglacial environment and allow us to collect uncontaminated samples.

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The boreholes will be used specifically to: (1) collect samples of subglacial water, sediments, and basal ice for biological, geochemical, glaciological, sedimentological, and micropaleontological analyses; (2) measure subglacial physical and chemical conditions and determine their spatial variability; (3) investigate sedimentary features and components, subglacial water discharge, and basal ice at the grounded ice side of the Grounding Zone.

Science Questions: Life Beneath the Ice

We expect the microbial communities located beneath the Whillans Ice Stream to be a metabolically dynamic ecosystem, and specifically ask (1) What is the microbial community structure?, (2) How do the organisms make a living in this environment?, (3) What is the metabolic function of the community in situ? (4) How does microbial metabolism alter the geochemistry beneath the ice sheet?

The GBASE effort will integrate genomic and biogeochemical information to define the relationship between structure and function of this previously unexplored ecosystem; results will be used by investigators of LISSARD and RAGES (the other two components of the WISSARD project) to cast their findings in a holistic ecosystem perspective. The study of life associated with our planet's ice sheets will provide fundamental information on the physiological and molecular properties of the microbiota which exist under dark and cold conditions. GBASE discoveries will provide a better understanding of biogeochemical processes involved with elemental transformations on our planet.

Scientific Significance

Discoveries of microbial life in lake ice, glacial ice, and subglacial sediments indicate that the ice-covered Antarctic continent is not a lifeless polar desert but rather an oasis full of life in what would otherwise appear to be an inhospitable environment (Priscu et al. 1998, 1999, 2008).

Recent estimates of bacterial abundance in and under the Antarctic ice sheets have revealed the presence of a previously unrecognized carbon pool that rivals that of other global carbon reservoirs. Priscu et al. (2008) recently estimated the volume of groundwater beneath the Antarctic ice sheets to be ~106 km3. Using bacterial estimates of 106 cell g-1 measured in subglacial sediment from beneath the Kamb Ice Stream (KIS) in West Antarctica (Lanoil et al.2009), these authors further estimated that Antarctic subglacial sediments harbor ~10^29 bacterial cells, which exceeds bacterial carbon in surface freshwater systems and is about 70% of bacterial carbon found in all surface soils on our planet (Whitman et al. 1998).

GBASE investigations will provide a better understanding of the biological diversity of the organisms that live in these cold and dark environments, and the biogeochemical processes that occur in and under the ice. As part of the WISSARD program, GBASE is investigating what may be some of the last unexplored aquatic environments on Earth, which represent a potential analogue for extraterrestrial life habitats on Europa and Mars.