Scientists first drilled a well in the subglacial Lake Mercer in the west of Antarctica and took samples of its water. Under a kilometer thick layer of ice, the researchers found the remains of marine crustaceans, tardigrades and land plants. Experts cannot yet say with certainty how these organisms got to Mercer. In the near future, they plan to establish the age of the found creatures, as well as study their DNA. The results of the study will show in what natural conditions these tiny organisms could live.
Members of the SALSA (Subglacial Antarctic Lakes Scientific Access) expedition drilled a well for the first time in the subglacial Lake Mercer in the west of Antarctica. Using a water-fed thermal drill, the scientists were able to make a hole 60 cm in diameter in a kilometer thick ice. In the collected water samples, the researchers found tiny remains of marine crustaceans, tardigrades and antennae of plants.
Experts noted that the obtained water samples contain enough oxygen to support the life of living things, as well as a lot of bacteria - at least 10 thousand cells per milliliter. However, researchers doubt that microorganisms could multiply fast enough to feed the inhabitants of the lake.
Some of the findings have puzzled scientists. So, according to the researchers, tardigrades prefer moist soils, and the discovered plants are found exclusively on the surface of the Earth.
Scientists suggested that these species got into the lake along with the river water of the Transantarctic Mountains 50 km from Mercer. This could have happened during a warmer period, when the glaciers were retreating - either during the last 10 thousand years, or 120 thousand years ago. With the onset of cold weather, the formed "oases of life" found themselves in an ice trap.
Scientists have put forward another version explaining the presence of tiny sea creatures in the lake. About 5-10 thousand years ago, the ice cover thinned for a short time. This allowed seawater to penetrate hundreds of meters of “floating” ice and reach modern-day Mercer.
According to researchers, something similar could have happened in other parts of Antarctica. Millions of years ago, it was warmer on the mainland, and there was an ocean on the territory of the modern lake. The gradual uplift of Antarctica as a result of geological processes turned shallow oceanic bays into isolated lakes. The tiny marine crustaceans may have had to survive for thousands of years in some of these lakes, trapped under the ice.
In the near future, scientists will deliver the remains of the found creatures to the United States, where, using radiocarbon dating, they will establish their age, and also sequenced their DNA. The results of the study will show in what natural conditions the discovered organisms could exist.
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According to Slavek Tulachik, a glaciologist at the University of California, nothing like this has ever been found under the Antarctic ice. Tulachik was one of the leaders of the only previous expedition in 2013, during which scientists drilled a well into the subglacial Willans Lake, also located in the west of Antarctica. At that time, many bacteria were found in the water samples taken, but there were no signs of the existence of organisms with a more complex organization.
Anastasia Ksenofontova