Toxic algae bloom suspected in deaths of sea lions and dolphins on Southern California coast

Experts believe a toxic algae bloom is the cause of hundreds of sick and dead sea lions and dolphins that have washed up along Southern California beaches this month.

Marine mammal rescue organizations were flooded with reports of hundreds of dead sea lions in the first few weeks of June, according to a statement by the National Oceanic and Atmospheric Administration's National Marine Fisheries Service, known as NOAA Fisheries. The number of dead dolphins has reached about 100, according to Michelle Berman Kowalewski, founder and director of the Channel Islands Cetacean Research Unit, a Santa Barbara-based biosurveillance organization.

“We are managing more than 200 reports of marine mammals in distress each day,” Ruth Dover, co-founder and managing director of the Channel Islands Marine & Wildlife Institute, told NOAA Fisheries. "We are doing the best we can to keep up with the intense pace."

NOAA Fisheries said the Channel Islands Marine & Wildlife Institute has received more than 1,000 reports of sick and dead marine mammals from June 8 to June 14. Experts suspect the animals are victims of domoic acid, a neurotoxin produced by the algae Pseudo-nitzschia, according to NOAA Fisheries.

Rotting seaweed, dead fish, no sand:Climate change threatens to ruin US beaches

Severe algae outbreak

While seasonal outbreaks of domoic acid poisoning are common along the California coast, the current outbreak is unusually severe.

The algae is a natural occurrence but NOAA Fisheries said ocean conditions that favor the algae can sometimes cause widespread outbreaks involving hundreds of animals. The toxin enters the food chain and sickens animals when they eat prey.

"The spread of domoic acid this year appears to include more offshore areas unlike an episode last year when the neurotoxin was closer to the shoreline and primarily affected sea lions," NOAA Fisheries said in a statement. "The dolphins may reflect an even further offshore distribution of the toxin this year."

NOAA Fisheries said ocean monitoring organizations found high concentrations of domoic acid along Orange County and San Luis Obispo County. The algae was especially concentrated in the Santa Barbara Channel off the coast of Santa Barbara and Ventura counties.

"The spread of domoic acid this year appears to include more offshore areas unlike an episode last year when the neurotoxin was closer to the shoreline and primarily affected sea lions," NOAA Fisheries said in a statement. "The dolphins may reflect an even further offshore distribution of the toxin this year."

NOAA Fisheries said ocean monitoring organizations found high concentrations of domoic acid along Orange County and San Luis Obispo County. The algae was especially concentrated in the Santa Barbara Channel off the coast of Santa Barbara and Ventura counties.

Contributing: The Associated Press