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What’s Really Going on in Lake Vostok?
9 July 2013 6:30 pm
Antarctica’s Lake Vostok, a giant body of water buried beneath about 4000 meters 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 radar altimetry—which measures surface deformation—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 body of water has been isolated from the planet’s 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 on other icy worlds?
This past week, Vostok has vaulted back into headlines, some of which are suggesting that scientists have now found life in the waters. Did they? What do we now know about this mysterious lake?
Is there life in Lake Vostok?
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 meters of ice a formidable engineering task, but then there’s the issue of managing to retrieve samples from the long-buried lake 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 of water from the lake itself in early 2013. The team is now analyzing those samples.
When will we know those results?
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.
What other clues do we have that there might be life in the lake?
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 Science described microbes in the accretion ice 3590 meters below Vostok Station -- just a few hundred meters 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 found the potential for a complex microbial ecosystem of bacteria and fungi, possibly with distinct ecological zones.
So why is Vostok in the news again this week?
The most recent published findings appeared last week 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 3500 unique genetic sequences (mostly from bacteria, but there were some multicellular eukaryotes). And those 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.
What about fish? Are there fish in the lake?
… 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 likely populated the lake during that time. What is still living in the lake isn’t clear.
So, where do things stand?
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.
*Correction, 17 July, 3:45 p.m.: It was with satellite-based radar altimetry, not satellite-based laser altimetry, that the lake's presence was confirmed in 1993.