Sea lions are sick and dying along the Southern California coast. Here’s what to know

It looked like something out of an apocalyptic movie.

In recent weeks, herds of sick and dying marine animals have been flocking to the Southern California coast, including the beaches of Santa Barbara and Ventura.

The devastation was caused by a toxic algae outbreak on a scale never seen before in the region, according to the West Coast branch of NOAA Fisheries.

As of last week, local officials had estimated that more than 100 dolphins and more than 500 sea lions had been killed by the algal bloom. It appears that the toxins are slowly spreading through Northern California.

Samuel Dover, who heads the Channel Islands Marine & Wildlife Institute, has witnessed six algal blooms during his career and described the current one as the worst yet.

“The bloom is much bigger,” she told NPR. “This time it’s in the middle of the channel, where there are a lot of animals.”

What is an algal bloom?

Algae are generally benign plants, commonly seen in the form of pond scum or algae. But under certain conditions, they can grow out of control and generate deadly toxins.

When this happens, it is known as a bloom. It tends to be a problem for US states near the coast of the country and the Great Lakes. Over the years, algal blooms have contaminated tap water, forced the closure of beaches, discolored coastal waters and led to the deaths of countless animals.

Although algal blooms are considered a natural phenomenon, climate change and human activities play a role in their frequency and intensity.

In California, the algae outbreak is believed to have been caused by winds driving nutrient-rich water towards the algae, causing them to grow. That process is typically unrelated to climate change, but neither does it rule it out as a factor, according to scientists at the West Coast branch of NOAA Fisheries.

What are algae doing to sea lions in California?

The bloom in California is producing domoic acid, which generally has no effect on humans but is poisonous to animals.

When a sea creature suffers from domoic acid poisoning, it affects the animal’s brain and causes seizures, erratic behavior, bulging eyes, and foaming at the mouth. Beachgoers have been warned to stay at least 50 feet away from sick animals in case they become aggressive.

There is no specific antidote or remedy for domoic acid poisoning. Veterinarians have given some animals anticonvulsants and kept them hydrated in hopes that the toxins will leave their bodies. The problem is that the longer the toxins remain in an animal’s system, the more difficult it becomes to cure the poisoning.

Pregnant adult sea lions have been hardest hit by the outbreak, according to Dover, of the Channel Islands Marine & Wildlife Institute.

When will it get better?

When Southern California was hit by an algal bloom last year, it lasted about six weeks, Dover said.

Similarly, the current epidemic, now in its eighth week, appears to be improving and fewer sick animals are appearing on the coasts.

By comparison, Dover said his group of volunteers has been receiving about 40 to 50 reports of sick animals a day lately. A month ago they were getting 40 to 50 reports an hour, although many reports tend to be duplicates of the same animal.

While this is a good sign, not much can be done to speed up the process. The harmful algal blooms are nearly impossible to clean up, especially at the scale that has emerged near California.