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Toxic lake in Costa Rica could hold clues to life on Mars

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The Poás volcano crater in Costa Rica (Wikimedia Commons)

By Mark Waghorn via SWNS

A vast toxic lake in Costa Rica could hold clues to life on Mars, according to new research.

It's one of the most hostile habitats on Earth - and is home to multiple organisms.

Water in the Poás volcano's crater reaches near boiling - and is full of metals.

It's ten million times too acidic to drink. There are also sudden explosions of steam, ash and rock.

Conditions resemble ancient hot springs that dotted the Red Planet's surface long ago.

First author Justin Wang, a graduate student at the University of Colorado Boulder, said: "One of our key findings is that, within this extreme volcanic lake, we detected only a few types of microorganisms - yet a potential multitude of ways for them to survive.

"We believe they do this by surviving on the fringes of the lake when eruptions are occurring. This is when having a relatively wide array of genes would be useful."

Hydrothermal environments may be where the earliest forms of life began on Earth - and potentially also on Mars.

via GIPHY

Specialist microbes called 'extremophiles' have a remarkable array of adaptations that enable them to thrive in such surroundings.

The lake is about 7,500 feet above sea level. It's 980 feet wide and about 100 feet deep.

An earlier study by the University of Colorado Boulder team suggested it was home to a single species of bacteria.

Named Acidiphilium, they are sometimes seen in drainage from coal mines. A follow-up study has now identified more.

The search for life on Mars has so far focused on streambeds or river deltas.

More attention should be paid to the sites of past hot springs - which were present on Mars for billions of years, say the researchers.

Explained Mr. Wang: "Our research provides a framework for how 'Earth life' could have existed in hydrothermal environments on Mars.

"But whether life ever existed on Mars and whether or not it resembles the microorganisms we have here is still a big question.

"We hope our research steers the conversation to prioritize searching for signs of life in these environments."

In February, NASA's Perseverance landed in Jezero crater - just north of the Martian equator.

A dried-up river bed is believed to have once fed a lake - depositing sediment in a fan-shaped delta visible from space.

The rover is currently drilling in the area for any signs of past microbial life.

Mr. Wang said: "For example, there are some good targets on the crater rim of Jezero Crater, which is where the Perseverance rover is right now."

Mapping the DNA of samples from the lake identified a wide array of biochemical capabilities to help them tolerate extreme and dynamic conditions.

These included pathways to create energy using sulfur, iron, arsenic and carbon during stress or starvation.

Mr. Wang said: "We expected a lot of the genes that we found, but we didn't expect this many given the lake's low biodiversity.

"This was quite a surprise, but it is absolutely elegant. It makes sense that this is how life would adapt to living in an active volcanic crater lake."

Despite lethal surroundings, hydrothermal systems provide most of the key ingredients for the evolution of life - including heat, water and energy.

This is why leading theories for both Earth and Mars focus on these locations.

The study was published in the journal Frontiers in Astronomy and Space Science.

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