Researchers studying Antarctica's Blood Falls say microbes in the salty outflow point to an ancient seawater source beneath the glacier. The finding adds biological evidence to the idea that the hidden brine system under Blood Falls is marine in origin.

According to the study, the flowing saltwater contains a microbial community tied to ocean environments rather than a random mix of organisms. That pattern suggests the brine trapped below the ice likely began as seawater and preserved signs of that history over long periods.

The work, published in Nature Geoscience, strengthens earlier thinking that Blood Falls is connected to a buried reservoir with a marine past. Instead of relying only on the chemistry of the water, the researchers used the presence of these microorganisms as another clue to where the brine came from.

The results could help scientists better understand how liquid water, salt and microbial life persist beneath Antarctic ice. They also offer a clearer picture of how ancient environmental conditions can remain locked below glaciers and still be detected today.