New Extremophiles: under antarctic ice in lakes (Introduction)

by David Turell , Monday, July 20, 2020, 18:33 (1370 days ago) @ David Turell

New discoveries from Antarctic lakes:

https://www.quantamagazine.org/john-priscu-finds-life-in-antarcticas-frozen-lakes-20200...

"But this is why I’ve done these winters: We’re figuring out how these ecosystems function with so little energy input and wanted to get a year-round look. One thing that’s keeping them alive is relic organic matter deposited from the ocean in an earlier geologic era. Metabolisms are so low that these organisms can survive by consuming this ancient food matter.

***

"The U.S. got a piece of the accretion ice from 11,800 feet below the surface, which was still 490 feet above the lake. I didn’t have much ice to work with. The sample I got was roughly 20 inches long and about 3.5 inches in diameter, but that piece of ice changed my life. We took it to the lab and examined it under the cleanest conditions, using a scanning electron microscope to look at cells and minerals, and an atomic force microscope to examine cells at the atomic level. And bingo, we started seeing microbes. Extrapolating from the accretion ice, we estimated bacterial concentrations on the lake’s surface of about 100,000 cells per milliliter — about one-tenth that found in the ocean or the average non-frozen lake.

***

"All the numbers we had extrapolated from the Vostok accretion ice — about 100,000 cells per millimeter — were confirmed in Lake Whillans. And this time we had solid proof — measurements from an actual lake sample, without having to rely on extrapolations. These are the moments you live for.

"There’s no sunlight beneath half a mile of ice, so of course there’s no photosynthesis. Instead, we’ve identified a number of microbes called chemolithoautotrophs, which basically eat minerals for a living. They get their energy from the oxidation of inorganic compounds, and they get carbon from carbon dioxide. We also discovered that methane was diffusing upward from the sediments, fueling bacteria that oxidize methane for energy.

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"We know that water can be trapped under glaciers in lakes or streams for a long time, but it eventually goes into the ocean. Lake Whillans drains every 10 years or so, and our geophysics teams have given us a pretty clear picture of the channels from Whillans and other lakes that flow into the Southern Ocean. It’s kind of like the Mississippi Delta with 3,000 feet of ice on it. We sampled roughly 6 miles out from where the Whillans’ flow meets the sea beneath the Ross Ice Shelf. And we found that enough nutrients [including carbon, nitrogen, phosphorus and iron] are being discharged from the lake to support a microbial ecosystem in the ocean waters below the ice. No one imagined that was possible.

***

"We drilled into Lake Mercer last year, going through about 3,500 feet of ice, and we found life there, too. But it’s different from what we see in Whillans, and the chemistry and dissolved oxygen levels are different. Cell density in Mercer is approximately 10 times lower. It’s not as productive as Whillans, which is three times saltier. Mercer gets a third of its water from East Antarctica, whereas Whillans gets most of its water from West Antarctica."

Comment: I assume the life found got there when the Antarctica was warm, and adapted as the climate changed. All living material is made to be tough. And to survive makes no mistakes as seen in complex multicellular forms.