Blood Falls

The saltwater source is a subglacial pool of unknown size overlain by about 400 metres (1,300 ft) of ice, several kilometers from its tiny outlet at Blood Falls.

The more soluble ferrous ions initially are dissolved in old seawater trapped in an ancient pocket remaining from the Antarctic Ocean when a fjord was isolated by the glacier in its progression during the Miocene period, some 5 million years ago, when the sea level was higher than today.

[3][4] According to geomicrobiologist Jill Mikucki at the University of Tennessee, water samples from Blood Falls contained at least 17 different types of microbes, and almost no oxygen.

From these samples, scientists isolated and characterized a type of bacteria capable of growing in salty water (halophilic), that thrives in the cold (psychrophile), and is heterotrophic, which they assigned to the genus Marinobacter.

Two gene clusters are related to the production of aryl polyenes, which function as antioxidants that protect the bacteria from reactive oxygen species.

Ice-covered oceans might have been the only refugium for microbial ecosystems when the Earth apparently was covered by glaciers at tropical latitudes during the Proterozoic eon about 650 to 750 million years ago.

Scientists of the NASA Astrobiology Institute speculate that these worlds could contain subglacial liquid water environments favorable to hosting elementary forms of life, which would be better protected at depth from ultraviolet and cosmic radiation than on the surface.