Water samples retrieved on January 28 from Lake Whillans, a sub-glacial lake about 800 metres beneath the western edge of the Antarctic ice-shelf, have shown possible signs of life. The announcement came from an American expedition that gained access to the 3.1-sq kilometre water body after boring through the shelf using a special hot-water drill.
The retrieved samples are significant because they come from a lake that has been isolated from the rest of the world for thousands of years. Moreover, due to the weight of the massive glacier above it, the lake exists under immense pressure (which shifts the freezing point of its water to a lower temperature).
The expedition, dubbed WISSARD (Whillans Ice Stream Subglacial Access Research Drilling), was undertaken to look for the presence of and investigate life in such an isolated and extreme sub-glacial environment. Researchers will also study the influence of such environments on the stability of continental ice-shelves.
As a first step in the hunt for life, a common dye was added to some samples to illuminate the DNA of microscopic organisms. When an affirmative bright green glow was observed in response, researchers knew that the water indeed harboured life.
Upcoming studies on the samples will throw light on how these organisms exist in such extreme conditions.
Dr. Ross Powell, one of the lead scientists on the expedition noted, in an email to this Correspondent, that the organisms “would most likely be chemolithotrophs because of the setting under the ice sheet.”
Chemolithotrophs are microorganisms capable of getting their energy from inorganic compounds, such as elemental sulphur, hydrogen sulphate, thiosulphates, etc. This is in contrast to other life-forms, like humans, which depend on organic compounds as food.
Because of their unorthodox needs, chemolithotrophs can survive harsh environments.
As Brent Christner, team member, told National Geographic , “The conditions faced by organisms in Lake Whillans are quite parallel to what we think it would be like on those icy moons,” referring to natural satellites of Jupiter and Saturn.
The full analyses will take at least a year, Dr. Powell added, “but we are starting to get some results now, showing there is viable life in this environment. We will be studying the cores we have collected after they arrive in our U.S. labs and they, [together with] any organisms they may house, could shed more light on [their environment’s] history.”
Lake Whillans itself is part of a densely interconnected network of streams that carry water into and out of sub-glacial pockets. As a result, researchers will also study the lake for its role in stabilising Antarctic ice-shelves.
Describing Whillans
Lake Whillans was first described by Dr. Helen Fricker, a glaciologist at the Scripps Institute of Oceanography and principal investigator of the Whillans team, in 2007.
She and her colleagues studied satellite data of the ice surface above the Whillans Ice Stream from 2003 to 2006 and noticed a periodic rising and falling of the surface that hinted at the presence of a lake.
In order to get beneath the ice sheet, a custom-designed hot-water drill was used to reduce chances of contamination by the equipment itself.
The drill works by blasting a jet of scalding water into the ice to bore a hole. The water then freezes because of the low temperatures and is removed as ice before another jet of water is blasted.
Once the surface of the lake was breached, the researchers inserted a probe to collect water samples from different points as well as some sediment from the lakebed.
