Originally published December 1 2012
Life found in oxygen-free depths of frozen Antarctic lake
by David Gutierrez, staff writer
(NaturalNews) For the first time, scientists have found life in one of the most challenging and hostile habitats ever discovered: the subfreezing depths of an Antarctic lake. The research was conducted by scientists from Nevada's Desert Research Institute and the University of Illinois-Chicago, and published in the Proceedings of the National Academy of Sciences.
"This study provides a window into one of the most unique ecosystems on Earth," said lead author Alison Murray.
The isolated lake, known as Lake Vida, is covered by a sheet of ice almost 20 meters (more than 60 feet) thick, meaning that no light ever reaches its depths. As a consequence, photosynthetic organisms are unable to survive and cannot provide the base of the food chain as they do in nearly every other habitat. Prior studies have established that the lake has been cut off from any outside biological or energetic influences for more than 3,000 years.
The lake is roughly six times saltier than seawater, allowing it to maintain an average year-round temperature of -13.5°C (8°F). On top of all this, Lake Vida has higher levels of nitrous oxide than any other natural body of water on the planet - levels that would be toxic to nearly all known organisms.
"Our knowledge of geochemical and microbial processes in lightless icy environments, especially at subzero temperatures, has been mostly [zero] 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."
Abundant lifeThe researchers followed strict protocols to survey the lake for life without contaminating it with external sources. They performed all their work in secure, sterile tents atop the lake ice. They drilled into the ice and melted it to examine the chemical composition of the lake, as well as gathering water from below the ice for biological sampling. Shockingly, the researchers found not just a few organisms, but abundant life consisting of a diverse collection of bacteria species.
The researchers remain unsure how life can exist in a place without any solar energy input at all. They have hypothesized that chemical reactions are taking place between the brine and the iron-rich sediments on the lake floor, producing not just nitrous oxide but also molecular hydrogen that bacteria can use as an energy source.
"It's plausible that a life-supporting energy source exists solely from the chemical reaction between anoxic salt water and the rock," co-author Christian Fritsen said.
"If that's the case," Murray said, "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."
Many scientists study extremophiles - organisms that are able to live in extreme environments that would kill most other life on Earth - in order to gain insights into the forms that life might take elsewhere in the universe. Cold-resistant organisms are considered particularly relevant for frigid planets like Mars.
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