California Sea Lions Have Brain Damage from Algal Bloom

Sea-Lion-MercuryNews- California sea lions have brain damage

Scientists from UC-Santa Cruz have discovered that many California sea lions have brain damage caused by toxic algal blooms. (

A tiny toxin called domoic acid, produced by marine algae known as pseudo-nitzschia, has long been known to destroy brain cells.  Recently, scientists at the University of California in Santa Cruz now believe that a number of California sea lions have brain damage that is caused by the same algae.

Over the last few years, biologists have noticed a profound loss of memory and navigational skills in many California sea lions. Frequently, weak sea mammals have struggled onto beaches trembling and acting confused.

Peter Cook, a researcher who presented the U.C. – Santa Cruz findings at the biannual Conference on the Biology of Marine Mammals in San Francisco, stated that the sea lions “have a lot of difficulty navigating and finding food.  They have no sense of which way to go.”  He went on to say that about one-third of stranded sea lions suffer from domoic acid poisoning … the toxin that is found in the algae.  The other stranded sea mammals have infections or other health problems.  Cook’s research will also be published this week in Science magazine.

While California and other coastal areas are frequently subject to algal blooms, the one that occurred along the Pacific Coast earlier this year was the largest ever recorded in the area.  It extended from Alaska down to Santa Barbara, California and lasted the entire summer, rather than just a few weeks in the spring, which is more normal.

This year’s algal bloom forced the state to shut down the commercial Dungeness and rock crab fisheries.  Discovering that many California sea lions have brain damage means that the problem may be much worse than first thought.

Kathi Lefebvre, of the Northwest Fisheries Science Center, part of the National Oceanic and Atmospheric Administration, reported that sick sea lions have been found in Washington and Oregon, as well as California.

Cook and his research team at UCSC brought the sea mammals to psychology labs at the university in order to study them.  They tested both their long term and short term memory.  While the healthy animals had no problem navigating mazes or finding buckets of fish that had been hidden, the animals with brain damage had lost those skills.

They also performed MRIs on the California sea lions with suspected brain damage, which revealed that they had a shrunken hippocampus, the part of the brain that is responsible for memory and navigation.

If California sea lions have brain damage from the algal bloom, it could also be a problem for humans who are exposed to the algae.  While domoic acid poisoning is currently rare in humans, it could become a more serious problem in the future if the algal blooms continue to worsen.

#SeaLions #CaliforniaSeaLions #PoisonedSeaLions

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