Antarctica's Lake Enigma, located between Amorphous Glaciers and Boulder Clay, usually has a temperature of 7 degrees Fahrenheit. In the winter months, that number can drop to -41 degrees. Experts have long believed that this remote lake is frozen and unlivable, but new evidence proves that at least some of the bacteria can find a way even in cold conditions.
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Researchers led by the National Research Council of Italy's Institute of Polar Sciences identified unique organisms during the “XXXV Italian Expedition to Antarctica” that took place from November 2019-January 2020. -11 and 36 feet deep. Below these icy blocks were layers of structural water columns at least 39 feet deep. Surprised by the discovery, the researchers then used a custom-made melting head drilling system that allowed them to extract water samples without contaminating them.
Underwater surveys of the bottom of Enigma Lake were conducted at four different drilling sites. Credit: Communications Earth & Environment
According to the group's paper, published on December 3rd Communication Earth and Environmentsubsequent lab tests confirmed a total of 21 bacterial and eukaryotic phyla in Lake Enigma's ice, stratified water column layers, and micromats. Examples included Pseudomonadota, Actinobacteriota and Bacteroidota, but as the research announcement explains, the most surprising finding was “the increase in the bacterium superphylum Patescibacteria.” These very simple life forms contain a small genome that allows their relatively small cells to carry out a select number of processes with limited metabolic functions.
“As a result, these bacteria have adopted a symbiotic or predatory lifestyle, completely dependent on their prokaryotic host cells,” the study authors wrote.
Although more research is needed, the team hypothesizes that ancient Lake Enigma may have once had a completely different ecosystem full of biodiversity. However, some time ago, the body of water formed a layer of permafrost that still exists today.
[Related: What will Antarctica look like in 2070?]
“The ice-enclosed planktonic and benthic microbiota of Lake Enigma likely represent a continuous legacy from the lake's ancient microbiome before it was glaciated,” the researchers concluded. Because of this, the current ecosystem consists of a “simple aquatic food complex,” although some remaining bacteria “may play an unusual role in the ecosystem of this lake that is not played in other frozen Antarctic lakes.”
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