Researchers have found an ancient ecosystem below an Antarctic glacier and learned that it survived millions of years by transforming sulfur and iron compounds for growth.
The ecosystem lives without light or oxygen in a pool of brine trapped below Taylor Glacier, next to frozen Lake Bonney in eastern Antarctica, said John Priscu, co-author of the research.
Priscu is a longtime Antarctic researcher and professor in the Department of Land Resources and Environmental Sciences at Montana State University.
The ecosystem contains a diversity of bacteria that thrive in cold, salty water loaded with iron and sulfur. The water averages 14 degrees Fahrenheit (10 degrees Centigrade below zero), but doesn't freeze because the water is three or four times saltier than the ocean.
The scientists made a breakthrough discovery when they learned that the bacteria convert key elements on Earth into food, Priscu said. The bacteria cycle sulfur compounds to access iron in the bedrock.
The ecosystem-- because it has been isolated for so long in extreme conditions -- could explain how life might exist on other planets and serve as a model for how life can exist under ice, Priscu said.
The finding will be published on the latest issue of the US journal Science on Friday.
Jill Mikucki, lead author of the research and a scientist of the Department of Earth and Planetary Science at Harvard University, added that life below the glacier may help scientists answer questions about life on "Snowball Earth," the period when large ice sheets covered the Earth.
The project also shows the power of multi-disciplinary collaborations, she said. Techniques in biogeochemistry, microbiology and molecular biology and other novel tests were used to figure out how the ecosystem could survive without photosynthesis.
The ecosystem has the "potential to be a modern analog to what geochemistry and biogeochemistry was like millions of years ago," Mikucki continued.
Priscu said researchers discovered the bacteria while investigating Blood Falls, a curious blood-red feature that flows from Taylor Glacier. They learned that the falls are red because they draw water from an iron rich pool, then discovered bacteria in their samples. The most common bacteria in the pool is Thiomicrospira arctica.
The researchers can't drill down to the pool because the glacier is too thick and the pool is too far back from the glacier's nose, Priscu said.
The pool, possibly less than three miles across, is believed to be a remnant of an ancient ocean that was trapped at least 1.5 million years ago when Taylor Glacier moved over Lake Bonney.
(Xinhua News Agency April 18, 2009)
