Antarctica: SA Agulhas II travels through Weddell Sea
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The icy continent is home to some 5,000 researchers around the year who study the unspoilt region to learn more about the Earth’s history and the effects of climate change. Its barren landscape gives them access to a unique habitat where they can probe the deserted landscape despite temperatures dropping to as low as -90C. But under the frozen surface lies a series of subglacial lakes teeming with diverse microbes that feed off nutrients in the water.
Until now, experts were baffled as to where these nutrients came from, but in a new study, they made a breakthrough after replicating erosion in these lakes by crushing up sediment samples in a lab.
It showed how the vital chemicals needed to sustain microbial communities are created.
Lead author Dr Beatriz Gill Olivas, from the University of Bristol, told Live Science: “Our study is completely different to any previous studies on subglacial lakes.
“Prior studies have looked at how the erosion of bedrock could produce gases in subglacial environments, but our study went further by looking at how erosion could also release biologically important nutrient sources to the water.”
She added that the findings could have “exciting implications” for studying how microbial life might develop elsewhere in the universe.
The researchers left the crushed rocks submerged for over 40 days and then analysed the water to see which chemicals had been released from the sediment.
They found a wide variety of different chemicals including hydrogen, methane, carbon dioxide and ammonium.
Most of these chemicals are released instantly from the sediment as it is crushed.
Dr Gill Olivas added: “During crushing, the sediments get broken down into much smaller particles.
“As a result of this, microscopic bubbles found in minerals, known as fluid inclusions, can be cracked open, to release gases and liquid that were previously trapped in these bubbles.”
One group of microbes, known as methanotrophs, feed off methane to create energy to grow.
The opposite happens in methanogens, which create energy by converting hydrogen and carbon dioxide into methane.
The lake also harbours specialised bacteria that get their energy by converting ammonium to nitrite and then into nitrate, a process known as nitrification.
The findings could be helpful in understanding how life developed, or is developing, on other planets like Mars, Pluto, or Jupiter’s moons.
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Dr Gill Olivas continued: “Lakes in Antarctica can be a proxy for extreme environments in other planetary systems.
“They offer a great insight into how microbial life might survive in other environments.
“We obviously can’t say that these processes will be definitely sustaining exoplanetary microbes.
“However, it definitely offers some insights into how microbes in icy planets and moons may survive.”
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