Scores of sick California sea lions have been reported along the Southern California coast in Ventura County, apparently stricken by a neurotoxin in algae ingested by fish they’ve consumed.
The Channel Islands Marine and Wildlife Institute, a marine animal rescue organization based in Santa Barbara, reported that its volunteers have been working from “sunrise to sunset” to help animals “in distress.”
“We are responding to 50 to 100 calls a day with multiple reports on individual animals,” the organization posted on Instagram.
Scientists believe the sea lions have been sickened by domoic acid, a potent, naturally produced neurotoxin created by a “bloom” of single-celled algae called pseudo-nitzschia. The neurotoxin accumulates in small fish, like sardines and anchovies, which the sea lions consume in large quantities.
Some research indicates the algae blooms are a byproduct of increased ocean pollution and higher water temperatures related to climate change.
Increasing numbers of sea lions are being sickened by the toxin each year, according to the National Centers for Coastal Ocean Science.
Ingesting the acid causes disturbing symptoms in sea lions, including “disorientation ... agitation, head bobbing and weaving/swaying back and forth, foaming at the mouth, bulging eyes,” according to the institute.
The acid can also be passed farther up the food chain to humans, and can be fatal to people if consumed in high doses, though that’s very rare, according to the California Department of Public Health. Crustaceans, fish and shellfish can have high levels of domoic acid without showing symptoms.
The California poisonings appear to have mostly affected adult female sea lions. Many animals recover about three days after the toxin passes through their system.
But because domoic acid attacks the brain and the heart, it can cause heart failure, seizures and permanent brain damage in sea lions, robbing the animals of basic survival functions, such as how to evade predators and find food.