Chile's rare salt flat fish faces threat from lithium mining project

A school of fish of 'Karachi' or 'Orestias Ascotanensis', swims inside a water source on Ascotan salt flat, in Ollague town area, in the Andean highlands, Antofagasta region, Chile October 31, 2024. Ivan Alvarado/File Photo

ASCOTAN SALT FLAT, Chile - At more than 3,700 meters (12,000 feet) above sea level, the "karachi" swims happily in dense salt flat waters, but locals worry a future lithium project will endanger this extreme-environment fish.

The Orestias ascotanensis is a small ray-finned fish that grows to just 7.5 centimeters (3 inches), but has adapted to the Ascotan salt flat's high concentrations of heavy metals and variable salinity.

The salt flat also sees high solar radiation and temperature variations that reach 26 Celsius (79 Fahrenheit) during the day and below freezing at night, according to Marco Mendez, a professor at the University of Chile who studies evolutionary biology.

Scientists at the Millennium Institute's genome center have been studying the fish and found genes that allow it to resist each element of its hostile environment, from solar radiation to heavy metals to low oxygen levels.

The fish has also evolved to do it quickly.

"We've seen how they've done this in a short evolutionary time because there are other variants of this fish in less hostile environments," said Miguel Allende, director of the institute.

"They've taken these genes and exacerbated them."

While the fish can survive extreme environments, it still needs an environment to live in and residents say copper mining has reduced the fish population due to water extraction.

"That's what's hurting them, when they take the water, the fish die," said Mauricio Anza, a local resident, who said people in the area are working to preserve the areas flora and fauna.

But Ascotan is also one of the salt flats where the government plans to launch a private lithium mining project, something locals and experts say must come with guarantees to safeguard the ecosystem.

"Mining activity, while important from an economic point of view, must be carried out with the aim of ensuring that this very particular environment is not lost forever," Allende said.

(Report by Rodrigo Gutierrez for Reuters TV, written by Fabian Cambero; editing by Alexander Villegas and Sandra Maler)