December 6, 2024

Unique microbial communities discovered beneath frozen surface of Antarctica's Lake Enigma. An international team of polar researchers has found several types of microbiota living in the water below the frozen surface of Antarctica's Lake Enigma. In their study, published in the journal Communications Earth & Environment, group members ventured to the lake. Using ground-penetrating radar, they found that there was water deep below its frozen surface, and drilled into the lake to obtain water samples for testing.

 

For many years, Lake Enigma was believed to be completely frozen—it was formed during a period when warmer temperatures prevailed. The assumption appeared logical; average temperatures in the area are just -14°C and the lowest temperatures in winter can reach -40.7°C. The lake is situated between two glaciers, Amorphous and Boulder Clay, suggesting they may have been the source of the water and ice in the lake.

 

In this new effort, the research team traveled to the lake over two summers in 2019 and 2020. They first conducted experiments using ground-penetrating radar and found evidence of water approximately 11 meters below the surface; the water depth was approximately 12 meters at its deepest. Intrigued by their finding, the team collected samples from the lake using drilling techniques allowing for water extraction without contaminating samples. They then brought the samples back to their lab for testing.

 

They found multiple examples of microbiota, including Pseudomonadota, Actinobacteriota and Bacteroidota. Perhaps more surprising, they found a proliferation of the bacteria superphylum Patescibacteria. Such bacteria are extremely simple—they have small cells and a small genome, and their cells can only carry out a limited number of processes.

 

The researchers suggest that the lake likely once teemed with living things before its top froze over permanently. The species alive today must be the descendants of those who somehow managed to survive. The researchers also noted that the lake should have dried up in the desert-like conditions long ago. The fact that it has not suggests it has an unknown water source.

 

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