Chicago's Brookfield Zoo is investigating an incident that led to the death of 54 stingrays on Friday after oxygen levels dropped in the animals' tank. The zoo's staff responded to an alarm set off by the its Aqua Net System, which monitors temperature, ozone and oxygen levels, a statement from the zoo's Facebook page revealed. Veterninarians rushed to try to fix the levels, but four southern stingrays and 50 cownose stingrays were lost.
"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."
The staff is now analyzing the life support system to determine the exact cause of the malfunction, according to CNN.
This is the second time stingrays at the Brookfield Zoo have died as a result of malfunctions in their tank. In 2008, 16 stingrays died after a malfunction occured in the pool's heating and cooling system, according to USA Today.
As a result of this incident, the Chicago Zoological Society has decided to not reopen the summer-long temporary exhibit for the remainder of the season.
