Scientists report the discovery of a thriving ecosystem of living organisms in one of Earth’s most extreme environments: beneath 14 meters of ice covering Antarctica’s frozen Lake Enigma.
A permanently frozen body of water in the Northern Foothills of Antarctica’s Victoria Land, the lake is one of the least likely locations on Earth that scientists would have expected to be home to life. Previously thought to be entirely frozen from top to bottom, now an international team of scientists have discovered an enormous body of unfrozen water hidden several meters below the lake’s icy exterior, in which a once-secret microbial ecosystem resides.
The discovery, part of the ENIGMA project funded by the National Antarctic Research Program, upends past findings about Lake Enigma, and offers unique insights into one of Earth’s most inhospitable environments.
The findings could also provide clues to researchers about the potential for microbial life’s existence within similar habitats elsewhere in our solar system, including icy moons like Saturn’s Enceladus and Jupiter’s Europa.
A Hidden Treasure Beneath Antarctic Ice
The multinational scientific team, which features members from the National Institute of Geophysics and Volcanology (INGV) and several other institutions, conducted their investigations of the frozen Antarctic lake using Italy’s nearby Mario Zucchelli Antarctic research base.
First discovered in 1989, Lake Enigma was originally thought to be entirely frozen. However, in November 2019 and January 2020, researchers conducted radar surveys that confirmed an abundance of stratified oligotrophic liquid water exists beneath close to 14 meters of surface ice covering the lake.
The discovery prompted researchers to drill into the frozen exterior of the lake and deploy underwater cameras, allowing them to capture highly detailed visuals of the lake’s hidden ecosystem.
Microbial Diversity Under Lake Enigma
“A remarkable feature of the Lake Enigma microbial ecosystem is the presence, and sometimes even dominance, of ultrasmall bacteria belonging to the superphylum Patescibacteria,” the researchers write of their discoveries in a recent paper that appeared in the journal Nature Communications Earth & Environment.
In the past, these particular bacteria had remained absent from past surveys of areas that include Antarctica’s McMurdo Dry Valleys.
“Cyanobacteria are virtually absent from Lake Enigma ice and water column although they are well represented in its extensive and diverse benthic microbial mats,” the team wrote.
Unlike anything documented in past similar discoveries involving Antarctica’s lakes, these microbial mats represent colonies of microorganisms comprised of layered films, the largest of which were an estimated 40 centimeters high and 60 centimeters wide.
The presence of Patescibacteria was revealed through DNA analysis of water samples retrieved from the lake. Given that these bacteria have never been discovered previously in such environments, currently researchers are uncertain whether their presence represents a symbiotic or predatory role in the unique ecosystem in which they inhabit.
“Collectively, these features reveal a new complexity in Antarctic lake food webs and demonstrate that in addition to phototrophic and simple chemotrophic metabolisms, both symbiotic and predatory lifestyles may exist,” the team writes.
Terrestrial and Extraterrestrial Implications
Ultimately, the new findings could have profound implications in the study of not only extremeophiles here on Earth, but also the kinds of environments that may be able to host life beyond Earth.
Scientists have long hypothesized that similar subsurface oceans on Jupiter’s moon Europa and Saturn’s moon Enceladus could host microbial life, and the team’s recent findings at Lake Enigma lend further weight to that possibility.
“The findings provide a fascinating glimpse into how life persists in some of the harshest conditions on Earth,” said Stefano Urbini, the project coordinator from INGV.
“They also serve as a model for understanding potential extraterrestrial ecosystems in our solar system,” he added.
The team’s paper, “The perennially ice-covered Lake Enigma, Antarctica supports unique microbial communities,” was published in Nature Communications Earth & Environment.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. He can be reached by email at micah@thedebrief.org. Follow his work at micahhanks.com and on X: @MicahHanks.