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By Emily Persico
In 1998, a red tide swept through California’s coast. It slowly crept up the food chain, taking cover in shellfish, anchovies, and other small sea animals before finally revealing itself in sea lions.
The first case of domoic acid toxicosis was diagnosed by the Marine Mammal Center soon after. Since then, it has lurked in the background, resurfacing on occasion to remind us that it’s never over, the sea lions never truly safe from its toxic clutches. And this year is just another heart-wrenching reminder.
Domoic acid is produced at the base of the food chain, by a very specific phytoplankton called Psedudonitzshia australis. While harmless under normal circumstances, domoic acid is a neurotoxin that can become dangerously concentrated given the right conditions.
“Water run off with fertilizers [to create] a bigger bloom and surface fish eat the algae,” says Wendy Leeds, the animal care coordinator at the Pacific Marine Mammal Center (PMMC).
Not surprisingly, there was a lot of water this year. Heavy rains washed nutrients from farms and dumped them straight into the sea, brandishing an algal bloom that would wipe through pregnant sea lions this spring.
The PMCC has rescued twelve pregnant sea lions in the last week, all of whom exhibited symptoms of domoic acid toxicosis. The PMCC is not the only organization noticing the outbreak – the National Oceanic and Atmospheric Administration has been getting increasingly more reports of sea lions in distress.
“It is unusual to see this many in a ten-day period,” warns Dr. Lauren Palmer of the PMMC.
Pregnant sea lions are exceedingly vulnerable to the brain-melting effects of the neurotoxin because of the sheer amount of fish they consume. In the hopes of nourishing their soon-to-be pups, they inadvertently poison their brains and destroy all possibility of motherhood.
In severe cases, domoic acid toxicosis will degrade the hippocampus of sea lions and humans beyond repair. It slows the heart and messes with the brain, disorienting its victim and causing seizures and lethargy.
This year, domoic acid toxicosis has looked like a sea lion, confused and desperate for help, climbing aboard an occupied ship, its head spinning. It looks like a bloodied sea lion lying in the road, barely clinging onto life after possibly being struck by a car. It looks like physical and emotional exhaustion for the people who spend their lives rehabilitating marine animals.
“In the past years, the sea lions told us there was no food. Now they’re telling us there may be another domoic acid bloom,” says Keith Matassa of the PMMC. “They are the canaries of the marine environment.”