BBC News, 8
July 2013
 |
| Researchers have to drill through thousands of metres of ice to reach the surface of Lake Vostok |
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Stories
There could
be some complex animals living in Lake Vostok, which lies close to 4km below
Antarctica's ice sheet.
The
possibility is raised by scientists who have sifted genetic material in ice drilled
from close to Vostok's surface.
They found
signatures for organisms such as bacteria that are often associated with marine
molluscs, crustaceans and even fish.
But the
team cautions in the PLoS One journal that this material may also represent
past contamination.
Scientists
now recognise that Antarctica is underlain by a complex network of rivers, and
many of the identified organisms, or their traces, could perhaps have been
delivered to Vostok from the ocean. The lake is 200m below sea level.
It is,
nonetheless, another fascinating twist in the story of this deeply buried lake.
First
identified in 1956 by the Russians and mapped in the 1990s by the British, Vostok
covers an area of 15,000 square km, and in places is 800m deep.
Researchers
believe it has not been open to the atmosphere for many millions of years, and
a drilling effort has recently tried to sample its waters.
The new
PLoS study examined genetic material - stretches of RNA - isolated from ice
that froze on to the ice sheet as it moved above the lake. The supposition was
that this content might hint at the type of life present in Vostok.
Thousands
of unique matches were identified with sequences already listed in public
databases.
The vast
majority (94%) of these matches were with bacteria, while a smaller group (6%)
were with more complex, multi-cellular organisms (eukaryotes). A handful of
links were made also to archaea - very primitive, single-celled microbes.
A large
number of bacterial sequences, reports the team, were from "animal
commensals, mutualists and pathogens… including those associated with annelids,
sea anemones, brachiopods, tardigrades and fish."
The team
also found matches to types of bacteria that thrive in hot environments, such
as around volcanic hydrothermal vents on the sea floor. If such vents existed
in Vostok, they could "provide sources of energy and nutrients vital for
organisms living in the lake", the team writes in PloS One.
Lake Vostok
is the largest of about 375 sub-glacial bodies of water now mapped under
Antarctica's ice sheet.
These
"ghost" lakes are kept in a liquid state by heat rising from the
rockbed below and from the pressure of all the ice pushing down from above.
Astrobiologists
have a particular interest in the lakes.
Conditions
in them may not be that different from those in the liquid water bodies thought
to exist under the surfaces of icy moons in the outer Solar System.
Places like
Europa, which orbits Jupiter, and Enceladus, which circles Saturn, may be among
the best places beyond Earth to go to look for alien organisms.
Related Articles:
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| Concerted efforts have been made recently to drill into lakes Vostok, Whillans and Ellsworth |
Related Articles:
“… Now, in the process of all of this, there's going to be renewed interest in Antarctica, and you're going to find some interesting things about the land under the ice. The topography of the land under the ice does not match the topography of the ice above. Some astonishing shapes will be revealed when you map the actual land under the ice. Points of mountains are going to be revealed, giving an entire different idea of what Antarctica might have been and what its purpose really is. The continent that is uninhabitable by Human Beings may very well be the engine of life for Human Beings. And I will leave it at that. …”
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