A bloom of harmful algae off the coast of Santa Barbara 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 have recorded at least three cases in the last three weeks where sea lions have been poisoned with domoic acid, a toxin produced by the plankton Pseudo-nitzschia that can alter the brains of marine vertebrates when eaten in large amounts.
"You end up with a neurological effect that might be reminiscent of something like Parkinson's in that the animals will then have seizures," said Clarissa Anderson, the director of Scripps Institution of Oceanography's Southern California Coastal Ocean Observing System, who has spent her career studying Harmful Algal Blooms (HAB) like the one of the coast of Santa Barbara.
"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.
The outbreak hasn't affected San Diego County wildlife as harshly as it has in years past, according to SeaWorld's Rescue team, which is working to rehabilitate the animals experiencing domoic acid poisoning. The team even returned one sea lion to sea Tuesday morning following a successful recovery, which isn't always possible.
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"[Rescuers will] get reports. People see them on the beach. They'll try to triage as many of those as they can. Often, some of these animals will just expire on the beaches before they can even get to a center," Anderson said. "We saw that last year when we had a thousand animals coming in, and it was incredibly overwhelming for these centers."
Last year, San Diego saw about a half-dozen suspected domoic acid deaths and more than a dozen more illnesses. One SeaWorld rescuer described last season's event as "one of the worst outbreaks of domoic acid toxicity that I’ve seen in my history here."
Rescue centers further up the coast have been harder hit this year. Dozens of marine mammals have been taken in by Orange County's Pacific Marine Mammal Center; And, near the source of the algae bloom, rescuers have been inundated with hundreds of cases since the bloom was reported as a concern by NOAA Fisheries in early August.
It's also not unusual to see these harmful algal booms in the spring to summer months, as an upwelling of deep ocean water provides nutrients to algae on the coastline. But the blooms are lasting for longer periods of time, which means marine mammals are more exposed to the neurotoxin.
"We're now into the month-long period, and that's how you start to get this kind of mass-stranding event where so many animals are being exposed to the toxin over a long period of time, and they're getting sicker and sicker," Anderson said. "The hope is always that this will be a very short event. And that the bloom will subside, and then you won't see too many animals coming in sick."
It's also a concern for scientists like Anderson that stronger blooms like the one off the coast of Santa Barbara are returning year after year, and earlier than previously recorded.
"This is not unusual in the sense that this is the first year we're seeing it, but this spate of three years in a row, I think, is a critical turning point that we need to look at as scientists and try to really understand what's happening that seems to have created this more frequency, higher frequency, but also really strong events," Anderson said.
Scripps Institution of Oceanography researchers are working to determine what nutrients are fueling the toxin-producing plankton. By understanding the precursors that lead to that toxin, researchers may be able to warn rescue crews when there may be an incoming surge of domoic acid.
"Mitigation of harmful algal blooms in the marine environment isn't always about stopping a bloom once it starts," Anderson said. "I think having the forewarning, getting critical resources to groups like the rescue centers that deal with the marine mammals, or to the state that monitors shellfish so that we don't get sick when we're consuming shellfish, all of these things are important in the sort of arsenal of tools that we have to combat the impacts of harmful algal blooms."
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 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. "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."
If there is a concern, the state will issue an advisory like the one currently in effect for Santa Barbara County. California also has an annual mussel quarantine for harvesting along the California coast to protect humans from consuming domoic acid.
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. Report dead injured or stranded marine mammals to the West Coast Region Stranding Hotline at 1-866-767-6114. The stranding team includes SeaWorld San Diego's rescue team but to contact them directly, call 800-541-SEAL.
