Ultra-salty lakes rich in carbon dioxide can support extreme life forms that differ from those found in other environments.

Dense saline water, laden with minerals, sinks to the ocean floor, where it can pool in depressions, creating unique brine lakes distinct from the upper waters. These brine pools, identified in various oceans, feature a unique chemical makeup—low in oxygen yet rich in particular minerals—allowing extreme microorganisms to thrive and evolve.

Recently, Froukje van der Zwan from King Abdullah University of Science and Technology in Saudi Arabia and her team have identified a novel brine pool that is warm, carbon-rich, and possibly nourished by underwater volcanic activity.

On a recent expedition to two underwater volcanoes in the Red Sea, Haty Bamons and Mabahismons, Van der Zwan and her colleagues found several brine pools located near the summit of the volcano, about five kilometers from mineral deposits where salt concentration increases. They also discovered regions with numerous hydrothermal vents releasing mineral-rich water at temperatures around 60°C (140°F).

Using a robotic vehicle for sampling revealed that the pool was warmer than the surrounding water and exhibited elevated levels of metallic elements like zinc and manganese.

The hot water vents also contained rich gas. “They show relatively high CO2 levels, similar to methane… however, unlike other hot water vents where liquids mix with seawater, this might function as a trap for these gases, being sequestered in the salt water here.”

Researchers are currently examining microbial samples collected from these pools to understand how life adapts to such extreme environments. Nearby hydrothermal vents revealed thick mats and diverse lifeforms, including polychaete worms and amphipods, featuring microorganisms considerably larger than known marine counterparts.

Living within a saline pool may offer insights into how life might thrive in harsh extraterrestrial environments, such as the salty, iron-rich oceans beneath the icy crust of Jupiter’s moon Europa. If hydrothermal activities exist beneath this surface, it could present scenarios similar to the iron-rich brine pool discovered by Van der Zwan and her research team.