COSTA MESA Biologists, assisted by the recent rains, have found the endangered Riverside fairy shrimp in a pool in Fairview Park for the first time, the city announced Friday.

Crews have been surveying the park’s 10 vernal pools since December as part of a study with the U.S. Department of Fish & Wildlife Service to document the San Diego fairy shrimp, a federally-protected species that has been found in the park in past years.

But earlier this month a small number of Riverside fairy shrimp were found in a pool on the east side of Placentia Avenue in the 208-acre park, said Bart Mejia, city engineer for Costa Mesa.

“It was the first time that that specific type of fairy shrimp was found at Fairview Park,” Mejia said. “It’s was pretty exciting.”

Both shrimp species are on the U.S. Fish and Wildlife Service endangered species list.

The emergence of both shrimp varieties was assisted by heavy rains in December and January, said Tony Bomkamp, a biologist for Glenn Lukos Associates who consults with the city on Fairview Park.

“It was the high rainfall that caused the ponding and it lasted pretty long, which is why we were able to see the Riverside shrimp emerge this year,” he said.

The Riverside fairy shrimp lives two to three months and has been on the endangered species list since 1993. It is mostly restricted to vernal pools in Riverside, Los Angeles and Orange counties, according to the Fish and Wildlife Service.

It’s likely the Riverside fairy shrimp, a warm-water species, was present in the pools but went undetected because they usually appear after the San Diego species, which prefers cold water and lives up to a month, Bomkamp said.

The park’s vernal pools are already off limits to the public, so no extra steps are required to protect them, said Raja Sethuraman, director of city public services.

The fairy shrimp habitat in Fairview Park was reviewed by U.S. Fish and Wildlife Service officials after an unauthorized granite path was installed over vernal pools near Estancia High School in 2013.

Richard Mehren, president of the Fairview Park Preservation Alliance, said the new find justifies the recently passed Measure AA, which requires a public vote for certain changes at the park.

“After the rainfall, everything is teeming with life,” he said.

Surveys of the park will continue through the rainy season, which ends around April 15, Sethuraman said.

Contact the writer: 714-796-2478 or lcasiano@scng.com