A bloom of harmful algae off the coast again this year is creating a neurotoxin that has caused sea lions and other marine mammals to exhibit Parkinson's-like symptoms up and down the Southern California coastline, including in San Diego.
SeaWorld San Diego says rescuers are currently caring for nine adult female sea lions that were poisoned with domoic acid, a toxin produced by the plankton Pseudo nitzschia, which can alter the brains of marine vertebrates when consumed in large amounts. Sadly, a 10th marine mammal, which was also being treated, has died. In all, 15 of the animals have been treated by SeaWorld since the outbreak began.
Clarissa Anderson, the director of Scripps Institution of Oceanography's Southern California Coastal Ocean Observing System, has spent her career studying Harmful Algal Blooms (HAB).
"You end up with a neurological effect that might be reminiscent of something like Parkinson's in that the animals will then have seizures," Anderson told NBC 7 in 2023. "They will throw up. They will be completely disoriented sometimes. You'll see them bobbing and weaving their heads on the beaches, sometimes foaming at the mouth. A myriad of symptoms that all basically categorize what one might expect from a neurotoxin."
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According to the National Oceanic Atmospheric Administration (NOAA), domoic acid is one the largest threats to marine mammals.
In 2023, San Diego saw about a half-dozen suspected domoic acid deaths and more than a dozen other animals sickened. One SeaWorld rescuer described the 2023 event as "one of the worst outbreaks of domoic acid toxicity that I’ve seen in my history here." Last year, SeaWord reported treating multiple animals for sickness as well.
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It's not unusual to see the harmful algal blooms in the spring to summer months, as an upwelling of deep ocean water provides nutrients to algae on the coastline, but this year's bloom in late winter/early spring is unusual, but not unprecedented.
The blooms are happening with greater regularity, however, according to Jeni Smith, the curator of SeaWorld San Diego's Rescue Program, who said they started to get calls for rescues in mid-February.
"They used to be every few years, but we've noticed in the last four or five years that we've had a demoic acid event every single year," Smith told NBC 7 on Thursday.
Incredibly, SeaWorld is getting about a hundred calls a day about sick animals, though it should be pointed out that some contacts are about the same sea lions. The illness can be treated in most cases, Smith said.
"So what we try to do is, we will flush them out with fluids, and we try to flush out the toxin, so a lot of it is giving them fluids, and we will monitor their behavior," Smith said.
Cases up north as well
The bloom is affecting marine life farther up the coast as well, where a number of sick sea lions were stranded on L.A. beaches continues to rise due to a toxic algal bloom.
The MMCC is operating in “crisis mode” and a triage space is being set up in the Center’s parking lot to increase space for additional patient admits as the volume of animals coming into MMCC’s hospital each day remains high.
Sea Lions are not the only animals being affected by the bloom. Beginning last week, dolphins also washed ashore from Long Beach to Malibu coasts, according to the Marine Mammal Care Center (MMCC). Down south in San Diego, officials said they were caring for a pelican suspected of demoic-acid poisoning, but they believe it is responding to treatment.
“We have over 60 patients right now, including some of our pups that were received earlier this year, but the majority of our patients are recovering from domoic acid toxicosis,” said Dave Bader, MMCC’s chief operating officer.
Can domoic acid affect humans?
Domoic acid is found in the same bloom that creates red tides and bioluminescence. But it is not harmful to swim in waters with high levels to domoic acid.
The acid — which is not acidic at all but rather an amino — is eaten by fish that are then eaten by marine mammals. It is possible that the toxin can be found in food that humans eat, although it is unlikely a human would eat as much fish as a seal. What is more likely is that humans could get sick from consuming shellfish that has high levels of domoic acid.
"We need to be very aware of the shellfish that we're eating," Anderson said in 2023. "And the state's great, the California Department of Public Health is great at testing the commercial stocks of shellfish to ensure that we do not get something called amnesic shellfish poisoning."
Symptoms of amnesic shellfish poisoning can occur within 30 minutes to a day after eating seafood. Symptoms include vomiting, diarrhea, abdominal cramps, headache and dizziness, which can subside on their own after a few days. Similar to domoic acid poisoning in sea lions, amnesic shellfish poisoning can also cause confusion, disorientation, seizures and loss of short-term memory. In rare cases, it can cause coma or death.
What do I do if I see a sick animal?
If an animal is exhibiting unusual behavior, do not approach them. Instead, call SeaWorld San Diego's rescue team at 800-541-SEAL.
