Lake Vida, the largest of several unique lakes found in the McMurdo Dry Valleys, contains no oxygen, is mostly frozen and possesses the highest nitrous oxide levels of any natural water body on Earth.
Despite the very cold, dark and isolated nature of the habitat, researchers found that the brine harbours a surprisingly diverse and abundant assemblage of bacteria that survive without a present-day source of energy from the Sun.
A briny liquid that is approximately six times saltier than seawater percolates throughout the icy environment that has an average temperature of minus 13.5 degrees centigrade.
"This study provides a window into one of the most unique ecosystems on Earth," said Dr Alison Murray, the report's lead author.
"Our knowledge of geochemical and microbial processes in lightless icy environments, especially at subzero temperatures, has been mostly unknown up until now," Murray said.
"This work expands our understanding of the types of life that can survive in these isolated, cryoecosystems and how different strategies may be used to exist in such challenging environments," Murray said in a statement.
Previous studies of Lake Vida dating back to 1996 indicate that the brine and its' inhabitants have been isolated from outside influences for more than 3,000 years.
Murray and her co-authors, including the project's principal investigator Dr Peter Doran of the University of Illinois at Chicago, developed stringent protocols and specialised equipment for their 2005 and 2010 field campaigns to sample the lake brine.
Geochemical analyses suggest that chemical reactions between the brine and the underlying iron-rich sediments generate nitrous oxide and molecular hydrogen. The latter, in part, may provide the energy needed to support the brine's diverse microbial life.
"It's plausible that a life-supporting energy source exists solely from the chemical reaction between anoxic salt water and the rock," explained Dr Christian Fritsen, a systems microbial ecologist and Research Professor in Desert Research Institute's Division of Earth and Ecosystem Sciences.
"If that's the case, this gives us an entirely new framework for thinking of how life can be supported in cryoecosystems on earth and in other icy worlds of the universe," Murray added.
The study was published in the journal Proceedings of the National Academy of Sciences.
