Ars Technica reports that a Russian research team reached the waters of Lake Vostok in Antarctica, one of the largest lakes on Earth, but buried under 3,700 meters (12, 139 ft.) of ice. Researchers believe that the presence of microbial life suggests that there may be animals living far below the ice.
Previously, scientists had taken samples of organisms from the undersides of glaciers. Some of the lake’s waters freeze onto the bottoms of glaciers that move across the surface of the lake, trapping any organisms within them.
The researchers tested the core samples—containing these trapped organisms—in the lab. They took extreme measures to eliminate contamination, such as dipping the ice cores into chilled bleach and wiping away anything that might have accumulated on their surfaces. They also compared the samples to ones created from frozen sterile water. They applied identical treatments to both samples.
Notwithstanding these controls, the DNA sequences were determined to be mostly human acne bacteria, the E. coli bacteria used in labs, and even DNA from cows; likely the result of contamination by the researchers.
However, by sequencing the DNA and RNA trapped in the lake ice itself, scientists have found a diverse community of bacterial species. Vostok may have the equivalent of deep-sea hydrothermal vents.
The range of bacterial species included groups usually found in freshwater and saltwater environments, in soil and sediments. DNA of cyanobacteria was also found. Though they function by means of photosynthesis, the ice above them would prevent light from reaching them.
Archaea – primitive forms of life – under similar conditions are customarily classed as extremophiles, but most of the sequences found here were bacterial.
Some bacterial groups had been previously found in deep-sea hydrothermal vents. These are fissures in the planet’s surface from which geothermally heated water emerges. Hydrothermal vents are commonly found near volcanic activity, areas where tectonic plates are moving apart, and ocean basins. They are the result geological activity and surface water or areas within the earth’s crust.
Because the Vostok fills a rift valley, such structures could form in the lake. Alternately, the bacteria could be living in water under the lake bottom, which is fed by an anomalously hot underlying mantle. They could be occasionally ejected into the lake itself.
But there may animals living in areas deeply covered with ice. While some of the DNA sequences are from fungi, others indicate multicellular life from animals, including arthropods, mollusks, cnidarians, and crustaceans. A number of bacterial species could be animal pathogens or part of the gut community.
In any event, the DNA obtained suggests that a large community of creatures live under the ice. There may be a thriving community, as is found in deep-sea vents, or one that is barely surviving. There may be two closely related species that have adapted to very different environments.
National Geographic reported in February of this year that a team of scientists had found and collected microbes from a lake hidden under more than a half-mile of ice in Antarctica.
The 50-member U.S. team broke through to a 20-square-mile subglacial lake. A commonly used dye was added to the water to illuminate the DNA of the microscopic organisms. A substantial green glow showed that microbes were indeed present. Many of the organisms are likely chemolithotrophs, which rely on inorganic compounds of iron, sulfur, and other elements for nourishment. A chemolithotroph is an organism with a metabolism such that it is able to use inorganic reduced compounds as a source of energy.
There is a vast system of lakes and streams deep below the surface of Antarctica. The existence of subglacial lakes and streams in Antarctica is a relatively new discovery.
Further investigation is needed to determine if there really are animals under the ice. This may require human beings to go down there and take a look.
By: Tom Ukinski