Oxygen shortage kills 54 rays at US zoo


More than 50 stingrays have died in shallow touchpool at an Illinois zoo after an equipment malfunction led to a drop in oxygen levels on Friday afternoon.

Staff at the Brookfield Zoo, located in the Chicago suburbs, noticed the rays behaving oddly after an alarm sounded on the system that regulates the tank's oxygen, ozone and temperature.

Oxygenation was restored to the Stingray Bay exhibit within 20 minutes due to the fast reactions of the staff, who added an air bubbler and submerged air pumps, but unfortunately the four Southern stingrays and 50 Cow-nose rays all died.

"We are devastated by the tragic loss of these animals," said Bill Zeigler, senior vice president of animal programs for the Chicago Zoological Society, which operates the zoo. "Our staff did everything possible to try and save the animals, but the situation could not be reversed."

Staff are currently analysing the life support system to determine the exact cause of the malfunction. The exhibit, which has been operating since 2007, will remain closed for the rest of the season.

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