(Image Credit: IMAGN) A sick sea lion is pictured at the Marine Mammal Care Center in San Pedro, California, on July 6, 2023.
San Pedro, California – A significant increase in marine mammals suffering from domoic acid poisoning, a neurotoxin produced by algal blooms, has been reported in California, raising concerns of another potentially deadly year for sea lions, seals, dolphins, and whales.
The Marine Mammal Care Center (MMCC) in San Pedro is currently treating over 30 animals affected by the toxic algal bloom, with eight new admissions on Wednesday alone. The recent surge indicates a growing problem as algal blooms off the California coast have become more frequent and intense in recent years.
“Since about 2015 we really saw kind of a steep change in how intense these blooms are and how long they last,” said Clarissa Anderson, a biological oceanographer at the Scripps Institution of Oceanography. “They’re definitely longer lasting in general than they were prior to about 2014.”
Domoic acid accumulates in small fish, such as sardines and anchovies, which are a primary food source for marine mammals. Ingesting large quantities of the toxin can cause seizures, heart failure, and permanent brain damage. While animals can naturally eliminate the toxin over time, repeated exposure leads to more severe and lasting effects.
Veterinarians at the MMCC are treating affected animals with fluids, domoic acid-free fish, and anti-seizure medications. Climate change, with its associated changes in water temperatures, is believed to be contributing to the increased intensity of these toxic blooms.
“The 25 to 30 years of data we have now is suggesting that something’s changing. They do appear to be getting more intense,” Anderson said, suggesting that changes in nutrient supply, possibly driven by climate change, are impacting the ecosystem.
The MMCC warns that if they continue to receive three to five new patients daily, their resources will be strained. Compounding the issue is the concurrent stranding of malnourished elephant seal pups, further burdening rescue centers.
Beachgoers are urged not to approach stranded marine mammals, as those affected by domoic acid can be particularly aggressive. Scientists are working to understand the causes and increasing frequency of these blooms, but funding challenges are hindering research efforts.
