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Life beneath the Antarctic ice? Stay tuned

Antarctica's Lake Vostok, a giant body of water buried beneath about 13,000 feet of ice, has had a surge of publicity in recent years. Subglacial lakes were suspected to exist beneath the continent's ice for decades. This particular lake's existence, in the vicinity of Vostok Station in East Antarctica, was first postulated in the 1960s by Andrei Kapitsa, a geographer and Antarctic explorer. But it was not until 1993 that satellite-based laser technology confirmed that the lake is there. It is the largest subglacial lake on the continent.

Since Lake Vostok's discovery, what life - if any - might exist within its waters has been a topic of extensive speculation. The lake has been isolated from the atmosphere for millions of years, with limited nutrients and complete darkness. Would it be barren? Or would it contain living fossils? And what might that life tell us about the extreme conditions in which life can thrive - not only on Earth but potentially also on other icy worlds?

Recently, Vostok has spawned headlines, some of which are suggesting that scientists have found life in the waters. Did they? What do we now know about this mysterious lake? A Q and A to help you figure out where things stand:

Q: Is there life in Lake Vostok?

A: Well . . . maybe. It's only in the past year or so that scientists have obtained access to the lake itself: Not only is drilling through thousands of feet of ice a formidable engineering task, but there's also the issue of retrieving samples from the water without contaminating them. In early 2012, after decades of drilling and strategizing about sample retrieval, a team of Russian scientists finally reached the surface of the lake. They collected the first samples in early 2013. The team is now analyzing those samples.

Q: When will we know those results?

A: The team has said that it hopes to have results within the next year. There have been tantalizing hints that there may be previously unidentified species of bacteria in the lake, but confirmation may wait until the researchers have finished their analyses.

Q: What other clues do we have that there might be life in the lake?

A: With the lake itself considered inaccessible due to fears of contamination, a number of scientists have examined ice cores taken from above the lake, focusing on the so-called accretion ice at the base of these cores. Accretion ice was once lake water that later froze and adhered to the overlying ice sheet - and what's in that ice might therefore provide clues to what's in the lake itself.

A 1999 paper in the journal Science described microbes in the accretion ice just a few hundred yards above the lake.

In the past decade, other teams have examined microbes in the accretion ice. Overall, researchers have generally observed low concentrations of such microbes relative to most environments on Earth - but they found the potential for a complex microbial ecosystem of bacteria and fungi, possibly with distinct ecological zones.

Q: So why was Vostok in the news again recently?

A: The most recent published findings appeared in PLOS One: Scientists led by Yury Shtarkman, a postdoc at Bowling Green State University in Ohio, identified a startlingly diverse array of microbes in the accretion ice - the most diverse suggested yet. By cultivating and sequencing nucleic acids found in the ice, they identified more than 3,500 unique genetic sequences (mostly from bacteria, though there also were some multicellular eukaryotes). And they were similar to those of creatures found in all sorts of habitats on the planet: lakes, marine environments, deep-sea sediments, thermal vents and, of course, icy environments.

Q: What about fish? Are there fish in the lake?

A: Maybe. Again, scientists are still looking at evidence in the ice, but the team found genetic sequences from crustaceans, mollusks, sea anemones and fish - and they found bacteria sequences that are common symbionts of larger species. But they also note that Lake Vostok was in contact with the atmosphere millions of years ago, so a complex network of organisms probably populated the lake during that time. What is still living in the lake isn't clear.

Q: So, where do things stand?

A: Although we're still waiting for direct evidence from the lake itself, the evidence certainly seems to be mounting that Vostok is far from sterile.

Life beneath the Antarctic ice? Stay tuned 07/16/13 [Last modified: Tuesday, July 16, 2013 9:43pm]

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