“Almost demonic” is how a surfer in Ventura County describes a sea lion that recently bit him. Down the coast in Long Beach, a 15-year-old says a sea lion attacked her when she was in the ocean over the weekend.
Marine mammal scientists say a massive algal bloom is releasing toxins, known as domoic acid, that are making some animals more aggressive, and causing others to wash ashore either dead or seriously ill.
Mattison Peters oversees veterinarian and response operations for the Marine Mammal Care Center (MMCC) in San Pedro. She says domoic acid is causing neurologic abnormalities in the animals, and they are less predictable.
Although domoic acid is harmless to fish, problems arise when larger species eat them. “The levels accumulate as you go up the food web. So fish eat the algae and are exposed to the toxin. But then larger fish eat them, more toxin accumulates within the fish. And then even more accumulates within marine mammals that consume large amounts of fish that might have been exposed to the toxin,” Peters says.
Currently, Marine Mammal Care Center staff are seeing a lot of California sea lions seizing on the beach or at their rehabilitation hospital, and the animals are lethargic, dull, and disoriented, Peters describes.
California sea lion Romeo, an adult male weighing more than 400 pounds, was rescued on February 25 from Dockweiler Beach with help from MMCC Pinniped Patrol volunteers and a lifeguard. Photo courtesy of Marine Mammal Care Center.
Her colleagues have also treated dolphins over the past weeks. “Rehabbing dolphins is a much more complicated issue, and with this disease process in general, they don't tend to do well. They tend to be very, very sick when they end up stranded on a beach. And so for those animals, the best option that we can offer them is to euthanize them on the beach.”
No antidote exists for the toxin itself, Peters says, so staff are flushing domoic acid out of the animals by giving them clean fish and fluids to consume.
“We also give them medications … to prevent their seizures. The more seizures they have, the worse their prognosis tends to be. And so if we can control their seizures by giving them anti-epileptic medications, that's the most important part of our initial treatment.”
Trained responders approach adult female California sea lion Paris at Paradise Cove in Malibu — to rescue her and bring her to the Marine Mammal Care Center to be treated for suspected domoic acid toxicosis. Photo courtesy of Marine Mammal Care Center.
Although algal blooms used to happen once every few years, now they’re annual, Peters notes.
Plus, NOAA is studying whether debris from January’s wildfires are linked to the blooms. Peters says nutrient composition and water temperatures do contribute, but it’s hard to determine whether there’s one cause or not.
Algal blooms typically last four to eight weeks, she says, “so I'm hoping that in the next couple of weeks things improve, but we'll see what happens.”