Previously thought to be entirely frozen, Lake Enigma in East Antarctica has revealed a unique ecosystem rich in microorganisms, according to a recent study by the Italian National Research Council.
Using ground-penetrating radar, researchers disproved earlier assumptions, uncovering liquid water and a vastly different environment compared to other Antarctic lakes.
Genetic analysis of water samples identified diverse microorganisms, including Bacteroidota, Actinobacteriota, and Pseudomonadota. The study also highlighted an abundance of ultra-small bacteria from the Patescibacteria superphylum, which possess extremely small cells and highly reduced genomes, performing minimal cellular activities.
The researchers suggest that the planktonic and benthic microbiota sealed by ice in Lake Enigma likely represents a legacy biota stemming from an ancient microbial ecosystem prior to freezing. Notably, the ultra-small Patescibacteria may play unusual roles in the lake's ecosystem, distinct from those in other ice-covered Antarctic lakes.
Despite these findings, the team remains uncertain about the source of liquid water in the lake. The combination of low rainfall and significant evaporation should lead to a loss of up to 200,000 cubic meters of water annually, indicating a hidden water source may still exist.
This discovery adds another layer of mystery to Lake Enigma.