[ad_1]
A small ephemeral lagoon in the hyper-arid core of the Atacama Desert. Credit: Carlos González-Silva
When the rains fell on the arid desert of Atacama, it was reasonable to expect flowers to appear. Instead, water brought death.
An international team of planetary astrobiologists has discovered that after encountering rainfall never seen before three years ago in the arid desert desert of Atacama in Chile, heavy rainfall has eliminated most microbes that had lived there.
"When the rains arrived at Atacama, we hoped for majestic flowers and deserts to enliven. On the contrary, we learned the opposite because we found that rain in the hyper-arid Atacama desert core caused the massive extinction of most local microbial species, "said astrobiologist co-author Alberto Fairen. invited from Cornell, in a new research published in Scientific Reports of Nature.
"Before the rains, hyperdry soils were inhabited by up to 16 different ancient microbial species. After the rain, only two to four species of microbes were found in the lagoons, "said Fairen, also a researcher at the Centro de Astrobiología de Madrid. "The extinction event was huge."
The core of Atacama rarely, if ever, sees rain. But thanks to climate change on the Pacific Ocean, according to the new document, rainfall was recorded in this part of the desert on March 25 and August 9, 2015. It rained again on June 7, 2017. Climate models suggest that similar rainfall can occur about once a century, but there has been no evidence of rain for 500 years.
The surprise precipitation has two implications for the biology of Mars.
The vast nitrate deposits in the Atacama Desert reflect long periods of extreme drought. These nitrate deposits are a food for microbes, Fairen said.
Nitrates were concentrated at the bottom of valleys and ancient lakes about 13 million years ago. "Nitrate deposits are the proof," said Fairen. "This could be analogous to the nitrate deposits recently discovered on Mars by the Curiosity mobile."
Another implication can go back four decades. With this new knowledge, researchers believe that science may want to revisit the Viking experiments on Mars in the 1970s, which involved incubating Martian soil samples in aqueous solutions.
"Our results show for the first time that suddenly delivering large amounts of water to microorganisms – perfectly suited for extracting lean and elusive moisture from the most hyperdry environments – will kill them at once." osmotic shock, "said Fairen.
In addition to Fairen, on the document, "Unprecedented rainfall decimates the surface microbial communities in the hyperarid core of the Atacama Desert," Armando Azua-Bustos of the Centro de Astrobiología and Carlos González-Silva of the University of Tarapacá, Arica, Chile, were the main authors. Fairen was funded by the European Research Council.
Source link
