To their surprise, scientists in Antarctica have discovered what appears to be small animal remains in mud dredged from a lake that has been covered by thick ice coats for thousands of years.
Researchers on this expedition – known as the Subglacial Antarctic Lakes Scientific Access, or SALSA – were the first to take samples of Lake Mercer, a water body about 600 kilometers from the South Pole. After drilling about one kilometer through ice at the end of December, the researchers lowered the instrument that carried water and sediment to the surface.
Seeing these samples under a microscope, the team found "some things that look like squashed spiders and types of crustaceans with legs … some other things that look like worms," said expedition member David Harwood, a micropaleontologist at University of Nebraska – Lincoln. The researchers also saw what appeared to be the remains of a long-known famous microscopic creature called a water bear.SN Online: 7/14/17) Checking the DNA of these remnants will help the researcher identify them more precisely.
This finding, first reported online by Natural on January 18, "really interesting," said Slawek Tulaczyk, a glaciologist at the University of California, Santa Cruz who was not part of the SALSA team. Until now, scientists have not considered Antarctic lakes such as Mercer an environment suitable for organisms larger than microbes.
When researchers in 2013 sampled Lake Whillans, the only snowy lake in Antarctica that had been drilled by scientists, "we found no evidence that was more complex than microbes," said SALSA team member Brent Christner, a microbiologist at the University of Florida in Gainesville (SN: 9/20/14, p. 10) "We have the same hope here."
The story of two lakes
New animal remains found at Lake Mercer came as a special surprise to researchers because samples taken from a neighboring lake, Lake Whillans, contained nothing but microbes.
It remains unclear whether the bodies of newly discovered animals have been left behind by creatures that actually live on Lake Mercer, Tulaczyk said. Ice or water may carry these fragments from the oceans or lakes further upstream in the Transantarctic Mountains. Carbon dating samples can help determine their age, which can provide clues about how and when these small animal carcasses arrive at Lake Mercer, he said.
If one of these animals is a resident of Lake Mercer, there is a possibility that some of them are still kicking there, Harwood said. "It's interesting to think that life can exist in truly extreme environments" such as Antarctic lakes that have been cut off from the oceans and the atmosphere for thousands of years, Harwood said. "If life is still there, it's important for our minds about what we might find in space."