Water quality kills more than half of KC zoo's rays

KANSAS CITY, Mo. -- The Kansas City Zoo had to temporarily shut down a hands-on exhibit of ocean rays after more than half the fish died.

Eight of the 15 Atlantic stingrays and cownose rays in the petting exhibit died over a four-day period beginning June 13 -- the result of water quality problems, zoo officials said.

The exhibit was closed to the public for a few hours on June 13 and 14, and permission for zoo visitors to touch the rays was suspended periodically throughout the week.

The zoo did not publicly announce there was a problem, but staffers informed visitors who asked about the dwindling population of rays, said spokeswoman Beth Paulsen.

She confirmed the deaths Friday, in response to queries from The Kansas City Star.

Zoo director Mark Wourms said there would inevitably be some glitches with a complex, new aquatic system.

"It's a shame the animals died," he said.

The rays' deaths came as the zoo was drawing national attention and criticism for last week's roundup of more than 200 unwelcome Canada geese, most of which were processed for food pantries.

In the past year, the zoo's professional accreditation has been at risk over staffing shortages, management problems and a dilapidated orangutan building. The zoo is building a new orangutan exhibit, and its accreditation was affirmed in March.

Since September the city has entered a contract with a private organization, Friends of the Zoo, to manage the zoo's daily operations.

Ordered more stingrays

The rays are a central element in the zoo's summer promotional campaign as it tries to boost attendance. The zoo has ordered 10 additional stingrays, and said it might prohibit human contact with the rays as conditions warrant.

The deaths of the rays appeared to have been caused by an imbalance of ammonia, nitrates, nitrites and oxygen in the 9,000-gallon saltwater tank, Paulsen said.

Zoo officials believe the imbalance was caused by an accumulation of oils and other substances as a result of thousands of people reaching their arms into the tank to touch the rays, she said. The exhibit includes washing stations, and those who put their hands into the tank are required to rinse up to their elbows with water before petting the rays.

A 'chain reaction'

Paulsen said the zoo staff tests the tank's water quality several times a day. She could not say why an imbalance was not detected before it became deadly.

"There was a sudden imbalance in the system that caused a very quick chain reaction," Paulsen said. "An aquatic system is very complex, and it doesn't take a lot for an imbalance to occur."

The tank has a filtration system, and a skimmer was installed last week to help remove surface oils and other substances from the water.

"We did our homework and set up a very good system," Wourms said of the tank. "We monitor it constantly, and we manipulate it constantly."

Jane Ballentine, a spokeswoman for the American Zoo and Aquarium Association, said permanent petting tanks such as the ray exhibit are fairly common at aquariums.

But the Kansas City Zoo's tank is a one-time project. The other large aquatic exhibit at the zoo, the freshwater sea lion pool, is protected from human contact.

The ocean ray exhibit runs through Aug. 31.