Microbes In Toxic Lakes Could Help Find Signs Of Ancient Martian Life

As scientists continue their work to find signs of ancient life on Mars, a group of researchers discovered microbes thriving in one of the harshest places on Earth — a toxic lake in Costa Rica’s Poás Volcano. The discovery could help the group understand more about Martian environments that might have supported life in the planet’s distant past.

Scientists know water existed on Mars, with many thinking that billions of years ago, the planet might have had the conditions to support life. Several missions are underway to better understand the Martian surface and look for signs of life, but the discovery of these microbes in Laguna Caliente — which represents volatile pools of water that existed on a young Mars — could prove critical for that work.

Though discovering life in harsh Mars-like conditions on Earth isn’t rare and scientists have seen living organisms in deserted areas, the lack of diversity of microbes seen in the latest research is what makes them special. Essentially, in the volcanic lake where waters are 10 million times more acidic than normal and temperatures touch boiling levels in a matter of hours, scientists spotted just a single species of bacteria belonging to the genus Acidiphilium.

Due to the extreme environments, the group expected to find no or a whole community of living organisms but were totally surprised by discovering only one species of microbes. “We’re at the limits of what life on Earth can tolerate,” Brian Hynek, who led the team to collect samples from the lake, said in a statement. “It’s not somewhere you want to spend a lot of time because you’d probably get covered in boiling mud and sulfur from the eruptions.”

The rarity of the find led the researcher to posit that if life existed on Mars sometime in the distant past, it might be similar to the organism living in the lake. “Even in an extremely harsh environment, there can still be life,” Hynek noted. “But then there’s very little life. Mars was just as extreme in its early history, so we should probably not expect to find evidence of large-scale biodiversity there.”

Though the climatic conditions prevailing on an ancient Mars have been a subject of long debate, a recent study published in Nature Geoscience suggested volcanic activity on the planet might have kept it modestly warm and prone to occasional rain even when it didn’t receive enough solar energy. These conditions with a little rain would have resulted in water flows that carved out the valleys and fluvial features seen on the Martian surface.

However, the warm and wet conditions wouldn’t have supported life, because photosynthetic organisms still needed sunlight to thrive. In those situations, according to the researcher, life may have survived like in the lake by using energy from iron and sulfur-rich minerals which were present in ancient hydrothermal systems on the Red Planet.

NASA’s 2020 Mars rover will look for signs of ancient life on the Red Planet and if this work is anything to go by, the first target zone for the robotic vehicle should be areas with possible signs of ancient volcanic activity. “Such environments are probably where life first evolved on Earth,” Hynek added. “If it happened on Mars, too, then I think those are the key places to look.”

The study, “Lack of Microbial Diversity in an Extreme Mars Analog Setting: Poás Volcano, Costa Rica,” was published in the journal Astrobiology.