Domoic Acid Toxicity in California Sea Lions

Guest Presenter: Dr. Cara Field
Director of Conservation Medicine
The Marine Mammal Center

Wednesday, June 11, 2025
6:00 PM on Zoom

In 1998, The Marine Mammal Center diagnosed the first case of domoic acid toxicosis in marine mammals. This condition is caused by harmful algal blooms, sometimes referred to as “red tides.”

Domoic acid is produced during certain harmful algal bloom events by a type of algae called Pseudo-nitzschia australis. This neurotoxin accumulates in small fish, like sardines and anchovies, which are then eaten by marine mammals like sea lions in large quantities.

Domoic acid attacks the brain and the heart causing seizures and heart failure. If left untreated, it usually causes permanent brain damage. The toxin will naturally flush from an animal’s system over time, but sea lions repeatedly exposed to the toxin will suffer longer-lasting and more serious effects.

Dr. Field is a certified Diplomate in the American College of Zoological Medicine, and one of only 35 Diplomates with the specialty of aquatic animal medicine. Additionally, in 2024, she was elected president of the International Association of Aquatic Animal Medicine. Dr. Field currently serves as an advisor for multiple aquatic animal conservation working groups.

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