More than 50 stingrays in a popular exhibit at a Chicago zoo died on Friday after oxygen levels suddenly dropped in the tank where the animals lived.
Chicago Brookfield Zoo said an equipment malfunction caused the dip in oxygen at the Stingray Bay habitat -- a shallow pool where visitors were allowed to touch and feed the 50 cownose rays and four southern stingrays that lived there.
According to the Chicago Tribune, an alarm alerted zoo employees to the change in the pool's oxygen levels on Friday afternoon.
Veterinary staff are said to have immediately rushed to the scene to provide treatment to the rays. However, “despite tireless efforts by staff, all the animals … succumbed,” the zoo said in a Facebook post, adding that it’s still investigating the cause of the malfunction.
"We are devastated by the tragic loss of these animals," Bill Zeigler, a senior vice president at the Chicago Zoological Society, which operates the zoo, said in a statement. ”Our staff did everything possible to try and save the animals, but the situation could not be reversed."
This isn’t the first time that stingrays have died en masse at the Chicago Brookfield Zoo due to an equipment malfunction. The Tribune reports that in 2008, 19 stingrays died after a faulty heater caused water temperatures to rise in a tank.
The Stingray Bay exhibit will be closed for the rest of the summer.
People for the Ethical Treatment of Animals (PETA) has called for the exhibit's permanent closure.
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