Rainfall in the Atacama Desert spells death for microbes

Scientists estimate that recent rainfalls count as the first time rain has fallen in the Atacama in about 500 years. Despite this dry history, on March 25 and August 9, 2015, and June 7, 2017, the rains poured in. 

“When the rains came to the Atacama, we were hoping for majestic blooms and deserts springing to life. Instead, we learned the contrary, as we found that rain in the hyper-arid core of the Atacama Desert caused a massive extinction of most of the indigenous microbial species there,” co-author Alberto Fairen, an astrobiologist, said in a statement.

Before the precipitation, which happened in 2015, in this arid, Mars-like desert, scientists estimate that there were up to 16 different species of microbes. But, after the rain, only two to four species remained. “The extinction event was massive,” Fairen said.

“Our results show for the first time that providing suddenly large amounts of water to microorganisms – exquisitely adapted to extract meager and elusive moisture from the most hyperdry environments – will kill them from osmotic shock,” Fairen said. Osmotic shock here refers to a sudden influx of water to a cell through its membrane. The flood can literally cause bacteria to burst open.

When the environment changes, so do the flora and fauna that live there.  Everything is and always has been moving and changing.  Nothing is static.

In a slightly wetter part of the Atacama Desert, flowers bloom after a rain.