Mercer Lake (Antarctica)
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Mercer Lake Mercer Subglacial Lake |
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| Geographical location | Marie Byrd Land , West Antarctica | |
| Drain | Under the ice towards the Ross Sea | |
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| Coordinates | 84 ° 39 ′ 15 ″ S , 149 ° 29 ′ 48 ″ W | |
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| Maximum depth | 15 m | |
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particularities |
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The Mercer Lake in the Antarctic is a subglacial lake about 1,000 meters below the Whillans glacier in the West Antarctic Marie Byrd Land . So it is a lake under the “ Antarctic ice armor ” of the polar ice cap of the South Pole . The naming was probably analogous to the Mercer Ridge .
Research history
Lake Vostok near the Russian station Vostok , which was first discovered in 1996 on the basis of satellite images under 3,600 meter thick ice in the area, is so far the largest of these Antarctic subglacial lakes, of which over 400 are suspected.
2013 was the first time one of them drilled : In Lake Whillans was found microorganisms .
On December 30, 2018, during one of the first ice drillings on the Whillans Glacier, in search of fossil remains of diatoms, sediment mud that had been recovered with a temperature probe, the remains of an "aged, blotchy and dark" chitin armor like a tiny crustacean were found . In the first core that was then taken , other “really beautiful crustacean shells” were found: “They were tiny, some as small as poppy seeds . And they were amber , looked fresh and crisp ”; sometimes even fine hairs of the senses were recognizable on the tanks, which triggered the idea here only recently of past, previously not suspected life. Five and eight different types of crustaceans were analyzed, which showed that there must be enough oxygen for animal life in the lake deep under the ice sheet .
In the meantime (April 2020) the Mercer Lake was sampled more extensively, and a surprisingly complex ecosystem was found . Last at least two million years ago, the sea level was so high here that the water reached into this region.
properties
The local Mercer Lake is about the size of Lake Como . According to satellite measurements, it is about 15 m deep, its water has a temperature of about 0.7 ° Celsius, there is a lack of nutrients . In addition, the lake is "hydraulically active", ie, it empties and fills in a 10-year cycle, but he emptied a kind subglacial river system in the ocean and fills presumably from yet another, lying above subglacial meltwater lakes new . Small amounts of methane rise from the sea floor , presumably partly from the decomposition of organic material from old marine sediments into the sea water. In turn, bacteria live in the water that feed on methane. About 10,000 bacterial cells per milliliter live here, very small and about ten times less than in samples from Lake Whillans, about 50 km away .
A large part of the biological activity is generated by chemotrophic organisms: unlike plants, they do not use light and carbon dioxide to produce and grow organic matter, but chemical energy from rocks , minerals and CO 2 , so the ecosystem is similar to that of hot methane sources , the Black Smokers in the deep sea .
See also
Individual evidence
- ↑ a b c Lake Mercer in Antarctica - crustaceans under eternal ice. Accessed April 13, 2020 (German).
- ↑ Bethan Davies: Subglacial Lakes
- ↑ a b Lake in the Antarctic - Frozen but complex. Accessed April 8, 2020 (German).