Algae ruining crab season may be causing brain damage in sea lions

SAUSALITO, Calif. (KTVU) - Researchers say the algae bloom that’s indefinitely delayed the Dungeness crab season may be causing brain damage in California sea lions.

UC Santa Cruz scientists studied the behavior of sea lions being treated at the Marine Mammal Center in Marin County and found evidence the sea lions were poisoned by the same toxins in algae that’s tainting crabs.

They say it’s affecting the sea lions’ ability to navigate and find food in the wild. 

The massive algae bloom, stretching from Santa Barbara to Alaska is hitting marine mammals hard.

At the Marine Mammal Center in Sausalito, sea mammals are treated for all manner of injuries, illnesses and strandings. Saving and rehabilitating them to live in the wild again is the top priority.

"They're incredibly smart. Sea lions are very, very smart. They're very comparable to dogs. They're also very sociable and very curious animals," says Sophie Guarasci, a Marine Mammal Center sea lion expert.

In recent months, there have been many cases of toxic algae poisoning. The sea mammals have eaten prey laden with toxic algae that causes brain damage. 

"The neurotoxin basically causes damage to a part of the brain called the hippocampus and that particularly affects some spatial memory. So, these animals can become disoriented.  They turn up in strange places and it can ultimately cause permanent epilepsy," says Ms. Guarasci.

That causes the mammals to lose their ability to navigate and, more importantly to find food. "Once they really have damage to the brain, that is unfortunately irreversible," says Guarasci.

Though the Marine Mammal Center can do a lot to save a lot of the mammals, the fact is, the algae blooms are so big this year, the mortality rate is way up.

"In an average year, our success rate has been around 50 percent; so 50 percent of the animals we manage to release back into the wild. This year has been particularly severe, with the size of the algae bloom, so our survival rate has actually gone down to about 30 percent," says Guarasci.

The brains of euthanized sea mammals are sent to Stanford for research on how to treat epilepsy in humans, making the mammals' tragic sacrifice of some value.