Deadly ocean toxin at worst-ever level

The natural toxin that killed hundreds of Southern California birds, sea lions, dolphins and other coastal marine life in the last two weeks had been at its highest levels ever recorded in local waters, scientists said Wednesday. And while concentrations of the neurotoxin domoic acid are lower now, the die-off hasn’t fully halted yet.

Wildlife care and rescue staff from throughout Southern California gathered at a bird rescue center in San Pedro for a news conference where USC professor David Caron announced the results. The week of April 26 showed twice as much domoic acid as ever before, Caron said.

“This is the worst,” he said. “It’s the highest numbers we’ve ever seen in terms of concentration.”

That much poison is bad news for animals.

The toxin moves up the food chain from tiny plankton to sardines and shellfish, which larger animals then eat in enough numbers to get a heavy dose.

Domoic acid can cause massive seizures and brain damage, Caron said.

“It’s a little chemical that mimics a molecule in the brain,” he said. “It causes neurons to continually fire until they damage the neurons — burn the nerves out.”

Local wildlife care officials say they’re seeing the effects of the higher poison levels in the animals brought in to their facilities.

“I think it is particularly unusual this year,” said Lisa Birkle, assistant wildlife director of the Wetlands and Wildlife Care Center in Huntington Beach, which handles birds found throughout much of the county. “Many of the animals that come in are not even exhibiting seizures this year. The birds appear to be dying too rapidly after ingesting it.”

The animal death toll appears to be far worse in Orange County than in Los Angeles County, officials said.

Of 165 birds taken into the Wetlands and Wildlife Care Center, only 13 are still alive. Of 53 sea lions taken into the Pacific Marine Mammal Center in Laguna Beach this spring, all but six have died, a nearly 90% mortality rate.

“And that doesn’t count the bags and bags of dead-on-arrival birds I haven’t been able to count yet,” care center director Debbie Mcguire said.

South L.A. County has also seen animal deaths. But the Marine Mammal Care Center in San Pedro saw only a 34% mortality rate from domoic acid this year, said staff veterinarian Lauren Palmer.

Even the final numbers will far underestimate the damage, experts said. In addition to the numerous dead animals that may never reach a care center, many surviving in the short run may have serious brain and nerve damage, Caron said.

People who find sick or dead animals should not try to help them on their own, but instead call wildlife centers or animal control officers.

The state Department of Health Services in April advised against eating bivalve shellfish, sardines and anchovies people catch themselves, and to avoid the organs of lobsters and crabs. Commercially caught clams, mussels, scallops and oysters are exempt from the warning.