Washington: Scientists had believed that Lake Vostok, which is buried under a glacier in Antarctica, and is so dark, deep and cold that it was a place which was totally uninhabitable.
But Dr. Scott Rogers, a Bowling Green State University professor of biological sciences, and his colleagues has revealed a surprising variety of life forms living and reproducing in this most extreme of environments.
Their finding details the thousands of species they identified through DNA and RNA sequencing.
Rogers said that the bounds on what is habitable and what is not are changing.
This is the fourth article the group has published about its Lake Vostok investigations.
The team included Dr. Paul Morris, biology, who with Scott and doctoral student Yury Shtarkman conducted most of the genetic analyses; former doctoral students Zeynep Kocer, now with the Department of Infectious Diseases, Division of Virology, at St. Jude`s Research Hospital in Memphis, performed most of the laboratory work; Ram Veerapaneni, now at BGSU Firelands, Tom D`Elia, now at Indian River State College in Florida, and undergraduate student Robyn Edgar, computer science.
The fourth-deepest lake on Earth, is also the largest of the 400-some subglacial lakes known in Antarctica. The ice that has covered it for the past 15 million years is now more than two miles deep, creating tremendous pressure in the lake.
Few nutrients are available inside the lake. The lake lies far below sea level in a depression that formed 60 million years ago when the continental plates shifted and cracked. The weather there is so harsh and unpredictable that scientists visiting must have special gear and take survival training.
Working with core sections removed from the deep layer of ice that accreted from lake water that froze onto the bottom of the glacier where it meets the lake, Rogers examined ice as clear as diamonds that formed in the great pressure and relatively warm temperatures found at that depth. The team sampled cores from two areas of the lake, the southern main basin and near an embayment on the southwestern end of the lake.
By sequencing the DNA and RNA from the accretion ice samples, the team identified thousands of bacteria, including some that are commonly found in the digestive systems of fish, crustaceans and annelid worms, in addition to fungi and two species of archaea, or single-celled organisms that tend to live in extreme environments.
Other species they identified are associated with habitats of lake or ocean sediments. Psychrophiles, or organisms that live in extreme cold, were found, along with heat-loving thermophiles, which suggests the presence of hydrothermal vents deep in the lake.
Rogers said the presence of marine and freshwater species supports the hypothesis that the lake once was connected to the ocean, and that the freshwater was deposited in the lake by the overriding glacier.
The largest number of species overall was found in the area near the embayment, including many that are common to freshwater environments, as well as marine species, psychrophiles and thermophiles. Numerous others were found that remain unidentified. The embayment appears to contain much of the biological activity in the lake.
The findings have been published in PLOS ONE.