Beneath the Taylor Glacier in Antarctica lies what appears to be a biological legacy from a time when seawater extended far into what are now the McMurdo Dry Valleys. At the famous Blood Falls, researchers have discovered microorganisms whose origins may be closely linked to this ancient sea.
The Blood Falls are among the most unusual natural phenomena in Antarctica. At the terminus of the Taylor Glacier, a highly saline, iron-rich liquid periodically seeps out of the ice. As soon as the dissolved iron comes into contact with oxygen, it oxidises and turns the ice and sediments a distinctive red colour.
An international research team led by Angela Zoumplis has now found evidence of an unusual community of complex microorganisms. The findings were published in Nature Geoscience in early August 2026.
Marine organisms beneath the ice
The researchers analysed a total of 167 samples from water, ice, mud and sediments in the McMurdo Dry Valleys, as well as control samples from McMurdo Sound.
Particularly in the red ice and sediment at the terminus of the Taylor Glacier, they found numerous microorganisms normally associated with marine habitats. These include diatoms, dinoflagellates, haptophytes and ciliates. In some samples, marine diatoms accounted for a particularly high proportion of the detected community.
Even more surprising were the RNA analyses. These showed that at least some of the organisms are metabolically active. They are therefore apparently not merely the biological remains of long-dead organisms.
Furthermore, according to the researchers, the transport of the organisms by wind from the coast inland cannot adequately explain the results. Some of the diatoms found at Blood Falls also differ genetically from present-day populations in McMurdo Sound.
Remnants of an ancient sea
The discovery is consistent with earlier studies of the water beneath the Taylor Glacier. During warmer climatic periods, seawater may have penetrated the Taylor Valley. Later, part of this saline water was cut off from the ocean by changes in sea level and the advance of the glacier and became trapped beneath the ice.
It is not yet fully clear how long this isolation has lasted. However, the findings suggest that the system at Blood Falls has preserved biological traces of a former connection to the sea.
The highly saline brine plays a crucial role in this. Salt lowers the freezing point, allowing liquid water to remain beneath the glacier even under extremely cold Antarctic conditions.
For science, Blood Falls thus offer an extraordinary window into the past. The microorganisms found there could reveal how life adapts to extreme cold, high salinity and prolonged isolation and how biological communities can survive major changes to their environment.
Heiner Kubny, PolarJournal