The number of marine mammals in California affected by a neurological toxin from algae has surged in the past week, in what could be another deadly year for animals such as sea lions, seals, dolphins and larger whales.<\/p>\n
According to the Marine Mammal Care Center, a rescue facility based in San Pedro, California, the facility is treating more than 30 animals affected by a toxic algal bloom, with eight animals admitted on Wednesday. The algae bloom off the California coast has been on the rise in recent years, producing a neurological toxin called domoic acid.<\/p>\n
\u201cSince about 2015 we really saw kind of a steep change in how intense these blooms are and how long they last,\u201d said Clarissa Anderson, a biological oceanographer at the Scripps Institution of Oceanography. \u201cThey\u2019re definitely longer lasting in general than they were prior to about 2014.\u201d<\/p>\n
Anderson added: \u201cIn the last four years, the impacts have been really heavy on the marine mammal side, both sea lions, some fur seals, and quite a few long-beaked common dolphins.\u201d<\/p>\n
Domoic acid is a neurotoxin that accumulates in small fish such as sardines and anchovies, creatures that serve as common food sources for marine mammals such as sea lions. This toxin can affect animals and humans.<\/p>\n
When ingested in large quantities, domoic acid attacks the animal\u2019s brain and heart, which can lead to seizures and heart failure. It often causes permanent brain damage if left untreated. Although the toxin can naturally leave an animal\u2019s system over time, repeated exposure results in more severe and lasting effects.<\/p>\n
If sea lions receive care before any serious damage occurs, veterinarians can help flush the toxin from their system by administering fluids and providing domoic acid-free fish. Anti-seizure medications, similar to those used in humans, are also given to control seizures.<\/p>\n
Climate change seems to be leading to higher levels of domoic acid amid changing water temperatures. The first diagnosed case of domoic acid toxicosis in California sea lions was made in 1998 at the Marine Mammal Center, and cases of affected sea lions have been on the rise ever since.<\/p>\n
\u201cThe 25 to 30 years of data we have now is suggesting that something\u2019s changing. They do appear to be getting more intense,\u201d Anderson said of the blooms. She suggested that changes in nutrient supply, possibly propelled by global climate change, could be having ripple effects on the ecosystem.<\/p>\n
The extent of the current domoic acid outbreak remains uncertain, but the MMCC, for example, warned that if they continue to receive three to five new patients daily, their resources may become strained in the coming weeks.<\/p>\n
\u201cOn the science side we\u2019re trying to really study these blooms and understand what causes them and whether they are increasing in frequency,\u201d Anderson said, \u201cand that\u2019s primarily all federally funded, and that is in huge jeopardy right now considering what\u2019s happening on the Hill and with Doge, so we\u2019re struggling I think from all ends on the resource end of this.\u201d<\/p>\n
To make matters worse, this is also the time of year when malnourished elephant seal pups begin stranding along Los Angeles county beaches, which could further hinder the ability for rescue centers to intake new animals.<\/p>\n
On Thursday, the MMCC reminded beachgoers in an Instagram post not to approach stranded marine mammals.<\/p>\n
\u201cWhile it is always dangerous to approach a marine mammal on the beach, sea lions affected by domoic acid can be especially aggressive, often awaking from a seizure with little notice,\u201d reads the post.<\/p>\n
Anderson said predicting domoic acid events is more complex than it looks, not only because it\u2019s hard to forecast when the organism will bloom and produce toxins, but also because the impact on animals varies.<\/p>\n
\u201cIf the anchovies are swimming more at the surface, then you can imagine pelicans being more impacted because they don\u2019t dive too deep,\u201d Anderson said.<\/p>\n
She added that multiple factors must align \u2013 bloom location, the feeding patterns of anchovies (which transfer the toxin), and the presence of top predators \u2013 to create the kinds of effects seen in recent years.<\/p>\n
This article<\/a> by Coral Murphy Marcos was first published by The Guardian on 10 March 2025. Lead Image: Sea lions suffering from neurological conditions caused by a toxic bloom off the Malibu coast are treated at the Marine Mammal Care Center in San Pedro. Photograph: Drew A Kelley\/AP.<\/i><\/p>\n Wildlife continues to face threats, which include hunting, poaching, illegal trade in animal products, habitat loss as well as a rapidly changing climate.<\/p>\n Become a Wildlife Champion today by supporting our conservation partners<\/a> with a monthly donation as little as $1.<\/p>\nWhat you can do<\/h2>\n