How the California Wildfires affected the Pacific ocean

On January 7th, 2025, the Palisades fires ignited, burning nearly 23,000 acres in the county of Los Angeles, California. Homes, schools, wildlife, and lives were lost during the 24 days the fires burned. However, now, the damage expands further than just on land; it extends to the ocean.

Runoff from fire chemicals, debris from homes along Malibu Beach, ash, and much more from the fires all acted as fertilizers, feeding an alga called Pseudo-nitzschia. This algal bloom typically occurs during spring and fall due to the upwelling of cold water, which brings nutrients in the bottom of the ocean. It is a natural occurrence, but in recent years, due to warming ocean temperatures and increased urban runoff, the blooms have become bigger and more dangerous. Pseudo-nitzschia produces a neurotoxin called domoic acid, which harms marine life and even humans.

Domoic acid is a naturally occurring potent neurotoxin that can work its way up the food chain, starting at plankton up to mammals like sea lions. Smaller fish consume the plankton, and then mammals consume the fish who have eaten the infected plankton. Though domoic acid is naturally occurring each year, there is an increase from the fires. As the firefighters use chemicals to fight fires along the Pacific Ocean in Malibu and other towns, the chemical runoff fuels the growth of the Pseudo-nitzschia alga bloom, increasing the amount of domoic acid that sea life consumes.

Image of sea lions at The Marine Mammal Care Center in San Pedro, California from USA Today

A result of mammals consuming domoic acid can be fatal, affecting the food chain. Sea lions that consume fish that have eaten algae with domoic acid can have seizures, brain damage, and sometimes die. Domoic acid also affects shellfish that humans eat. Shellfish like clams and mussels that have consumed the algae with domoic acid can get Amnesic Shellfish Poison. Humans who consume shellfish with Amnesic Shellfish Poisoning can experience headaches, vomiting, cramps, and sometimes short-term memory loss.

One thing we can do to improve this and ensure a bad bloom does not happen again is try to fix the chemicals we use to fight fires, working with scientists to come up with a safe option when fighting fires near the ocean. There were also many reports that the weeks following the fires, there was debris left from homes and open sewage tanks on the beach where homes had been destroyed in fires. Ensuring that we pick up what we left and working to improve fire chemical safety by the water is the best way we can work to protect our ocean from a large and long algal bloom like this from occurring again.