Scientists Find Life in the Cold and Dark Under Antarctic Ice
For the first time, scientists report, they have found bacteria living in the cold and dark deep under the Antarctic
ice, a discovery that might advance knowledge of how life could survive
on other planets or moons and that offers the first glimpse of a vast
ecosystem of microscopic life in underground lakes in Antarctica.
Alberto Behar, Jet Propulsion Laboratory/Arizona State University; underwater camera financed by National Science Foundation and NASA
The first view of the bottom of subglacial Lake Whillans in Antarctica.
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A network of hundreds of lakes lies sandwiched between the continent’s
land and the ice that covers it, and scientists had thought that it
could harbor life. The discovery is the first confirmation.
“It transforms the way we view the Antarctic continent,” said John C.
Priscu of Montana State University, a leader of the scientific
expedition.
After drilling through a half-mile of ice into the 23-square-mile,
5-foot-deep Lake Whillans, the expedition scientists recovered water and
sediment samples that showed clear signs of life, Dr. Priscu said,
speaking from McMurdo Station in Antarctica on Tuesday. They saw cells
under a microscope, and chemical tests showed that the cells were alive
and metabolizing energy.
Dr. Priscu said that every precaution had been taken to prevent
contamination of the lake with bacteria from the surface or the
overlying ice. In addition, he said, the concentrations of life were
higher in the lake than in the borehole, and there were signs of life in
the lake bottom’s sediment, which would be sealed off from
contamination.
Much more study, including DNA analysis, is needed to determine what
kinds of bacteria have been found and how they live, Dr. Priscu said.
There is no sunlight, so the bacteria must depend on organic material
that has drifted into the lake from other sources — for instance,
decaying microbes from melting glaciers — or on minerals in the rock of
the Antarctic continent.
Chris McKay, a NASA senior scientist, said in an e-mail that such
analysis could determine if the bacteria in Lake Whillans have
implications for the possible discovery of extraterrestrial life. “If it
was using a local energy source, it would be interesting,” he said. “If
it’s just consuming organics carried in from elsewhere, it is of much
less interest.” The reason, he said, is that elsewhere in the solar
system where there is good evidence of liquid water under thick ice
sheets, life would have to depend on minerals alone. “There is not going
to be oxygen on other worlds,” Mr. McKay said.
Slawek Tulaczyk of the University of California, Santa Cruz, another
leader of the science expedition, said that samples were drawn from as
deep as four feet in the sediment, and that oxygen decreased with the
depth of the sample.
The scientific project, called Wissard,
for Whillans Ice Stream Subglacial Access Research Drilling, was years
in the planning and is one of three efforts to investigate the lakes
that lie under the Antarctic ice.
A year ago, a Russian expedition penetrated the surface of Lake Vostok,
under two miles of ice. They found hints of life on samples from the
drill bit, but contamination from the kerosene drilling fluid was a
possibility. This year they recovered samples of frozen lake water that
are yet to be analyzed.
A British effort to reach Lake Ellsworth, under a mile of ice, was called off in December because of equipment problems.
The American effort, supported by $10 million from the National Science
Foundation and other grants, focused on Lake Whillans, which is quite
different from the other two lakes. It lies under a half-mile of ice,
less than the others, and its water is replenished in about a decade,
scientists believe, with meltwater from overlying ice. Lake Vostok is
much more sealed off from the surface and is thought to take 10,000
years for its waters to renew. Lake Ellsworth may turn over in about 700
years.
Although Lake Whillans may be more reachable than the other two, doing
anything in Antarctica is enormously difficult. It took a tractor convoy
12 days to take the drill and other equipment more than 500 miles over
the Ross Ice Shelf to the drilling site from the American research
station at McMurdo.
The scientists had four days to collect samples and obtain images of the
lake. Several lines of evidence convinced them that they had found
microbial life in the lake. First, they saw cells under the microscope
and confirmed that DNA was present.
Then they measured evidence of an enzyme that is important in metabolism
and a chemical called ATP, for adenosine triphosphate. Molecules of ATP
are essentially packets of energy, and their presence was a further
indication that the bacteria were living. Further, they found that
concentrations of ATP were higher in the lake water than in the water in
the borehole, which, Dr. Priscu said, meant that there was more life in
the lake and argued against any contamination.
Much further study will be done before scientific results are published
and other scientists can look at all the data. Dr. Priscu said that new
tests were being done each day, but that DNA tests would have to wait
until the scientists returned to the United States.
“Our stateside DNA sequence work will tell us who they are,” he said of
the microbes, “and, together with other experiments, tell us how they
make a living.”
But he said he was confident that the researchers had achieved the first
glimpse of an ecosystem that had been completely unknown. “It’s the
world’s largest wetland,” Dr. Priscu said.
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