In Southern California, rescuers are battling to save sea lions being poisoned by a toxin that occurs naturally in the sea lions' food supply.
Peter Wallerstein, who is on the front lines, tells CBS News Correspondent Sandra Hughes the culprit is a toxin called domoic acid, which is produced by naturally growing algae.
"The sea lions," says Wallerstein, "washed up onto the beach, and probably they've been there about 30 minutes; usually, they're up on their four flippers, with their head bobbing back and forth with the neurotoxin exploding in their brain."
The algae aren't new to Southern California waters. But, what's confounding scientists is why they're blooming so much more in past decade, Hughes points out.
Some blame global warming; others, agricultural runoff.
Either way, fish and other sea creatures eat the algae, then the sea lions eat the fish.
Jackie Jaakola hopes to save at least half the rescued sea lions at the Marine Mammal Care Center in San Pedro, Calif. where, in May, they had more animals sickened by domoic acid than ever before.
"When we first see the animals," Jaakola says, "they are pretty down and out. We give them medications to control their seizures, and we give them fluids to help flush the toxin from their system."
It's not just marine life threatened by the toxin, Hughes notes: In 1987, three people died and 104 were sickened on Prince Edward Island, Canada after eating tainted blue mussels.
This year, in California, the toxin is hitting pregnant sea lions the hardest.
"They're due to give birth (early this month). …The seizures do have an adverse impact on the pregnancies," Jakoola says.
Many are delivering stillborn pups or miscarrying in the ocean.
Still, wildlife officials say, with the high numbers of California sea lions, even an event like this shouldn't do long-term damage to the sea lion population.