In the McMurdo dry valleys of Antarctica, there exists a lake buried year-round under an ice cover. The ice is so thick that neither light nor oxygen can penetrate through to the hyper-saline brine below, which contains five to six times as much salt as typical ocean water. This salt prevents the water from freezing even at its average temperature of eight degrees Fahrenheit. Still, despite these hostile conditions, scientists have discovered that certain species of bacteria live and thrive within the depths of Lake Vida.
Researchers Peter Doran, of the University of Illinois Earth Science Department, and Alison Murray, of Nevada’s Desert Research institute, published the details of their findings online in the journal Proceedings of the National Academy of Sciences. The significance of their discovery is twofold: it expands the accepted boundaries for life, encouraging scientists to search for life in even more extreme environments on Earth and on other planets, and it provides additional insight into the evolution of species.
According to Doran, the presence of life in Lake Vida supports the idea that wherever you find water, you find life. Communities of bacteria persist even with icy cold temperatures, overwhelming salt concentrations and isolation from sunlight and other sources of energy. However, what Lake Vida does offer its resident bacteria is a reservoir of carbon compounds that function as the molecular building blocks of life. It also contains nitrous oxide and molecular hydrogen, chemicals that react with each other to provide the lake with a self-sustaining energy source.
Doran and Murray were surprised by both the diversity of bacterial species they found and the abundance of their colonies. The existing bacteria all belong to ancient species, suggesting that they have occupied Lake Vida for millennia on their own, with self-contained sources of fuel.
This discovery revolutionizes the search for life on other planets, as scientists now will not only explore the land for life but will also look to subsurface bodies of water. The habitat of Lake Vida, with its completely depleted oxygen and other harsh conditions, resembles the environment that might be found on Mars, for example.
Scientists also hope to explore similar lakes in Antarctica and to search deeper strata of Lake Vida. To minimize contamination of the brine, which is normally isolated by thick ice, researchers have set up a sterile room at the top of the drill site while wearing white suits and utilizing the same precautions that are used in germ labs. The drilling process involves extending heated pipes downward to excavate the ice and collect samples from the waters below. These same procedures will be used to explore the bottom sediments of Lake Vida and other Antarctic bodies of water in the future.