Antarctica's mystery: a unique ecosystem teeming with life found beneath Lake Enigma

A team from the Italian National Research Council has used ground-penetrating radar to detect the presence of liquid water in Lake Enigma, located in the Victoria Land in eastern Antarctica. This contradicts previous assumptions that it was completely frozen.

Scientists have now discovered a huge hidden body of unfrozen water beneath its chunky ice surface. They also found a unique ecosystem teeming with life, writes Ifl Science. Genetic analysis of samples taken from the lake revealed a variety of different microorganisms living in the water, including Bacteroidota, Actinobacteriota, and Pseudomonadota.

According to the researchers, the water depth is at least 12 meters, but scientists clarify that the lake may be even deeper.

The average temperature in the lake is -14°C, and the lowest is -40.7°C. Due to such harsh temperatures, the unfrozen water remains covered with ice up to 11 meters all year round.

The permanent ice cover helps to isolate the lake from the outside world and contributes to the creation of a unique ecosystem of microorganisms. According to scientists, some of them may not be found anywhere else on Earth.

The microbial ecosystem in Lake Enigma is not even similar to other Antarctic lakes, such as those in the well-studied McMurdo Dry Valleys. This is likely due to its unique chemical and thermal properties.

Most importantly, this study showed that the water was enriched with large numbers of ultra-small superficial bacteria called Patescibacteria. These tiny bacteria have extremely small cells, contain very reduced genomes, and perform minimal cellular activities. They are simple but effective.

"The ice-sealed planktonic and benthic microbiota of Lake Enigma likely represent persistent legacy biota that arose from the lake’s ancient microbial ecosystem before the freeze-up," the study authors write, adding that in general, the microbiota of Lake Enigma occupies different trophic levels in a simple aquatic food web, ranging from primary production to ectosymbiosis and predation. "The ultrasmall Patescibacteria in particular may play unusual roles in the lake’s ecosystem that do not play out in other ice-covered Antarctic lakes," the scientists clarify.

The fact that the lake exists in Antarctica at all has led scientists to look for a hidden water replenishment system. After all, Antarctica is the largest desert on Earth because there is very little rain or snow. Due to the lack of precipitation, as well as intense evaporation from the sun and ultra-high gusty winds, the lake must lose up to 200,000 cubic meters of water every year, yet its waters have not run out.

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