Domoic Acid Kills Marine Animals

A female sea lion recuperating at the Pacific Marine Mammal Center. Photo by Ted Reckas.

The Pacific Marine Mammal Center in Laguna Canyon has received 27 sea lions and eight dolphins with signs of domoic acid poisoning from a harmful algal bloom over the last two weeks. Just two sea lions survived.

“We clearly have an event taking place. There have been dozens of animals coming in up and down the coast,” said David Caron, a phytoplankton expert and professor of microbial ecology at USC.

“We picked one dolphin up at Bolsa Chica on April 21, and it was having horrible seizures. We had to put that one to sleep. It was dying. We had to do something. They can’t live on land, so for a dolphin having seizures, there is no hope. We put it back in the water and it flipped to its side. It couldn’t even right itself,” said Michelle Hunter, director of the mammal center.

Domoic acid is a neurotoxin produced by Pseudo-nitzchia, a type of phytoplankton. It often blooms in the spring, after winter storms have caused nutrients like phosphorous, nitrogen, iron, carbon dioxide, carbonate and ammonium from deeper water rise to the surface, where sunlight is present, producing favorable conditions for the growth of Pseudo-nitzchia and the thousands of other species of phytoplankton. Spring is also when pregnant sea lions are eating up to double their normal amount of fish, concentrating the toxin in their blood stream. All of the sea lions that came to the mammal center were female, and 90 percent of them were pregnant according to Dr. Richard Evans, the center’s medical director.

“This is nasty stuff. When you get poisoned it doesn’t go away, and you don’t get better. You can get better but you are missing parts in the cabeza,” said Evans.

The acid affects birds, too. Over the last two weeks, 19 birds, including a brown pelican, a cormorant and Western Grebes have come in to the Wetlands and Wildlife Care Center in Huntington Beach.

A volunteer injets fish with medication for the center's aquatic patients. Photo by Ted Reckas.

“They have classic signs of domoic acid poisoning. One was hitting his head against the side of the cage. They have horrible seizures,” said Kelly Beavers, wildlife technician at the Center.

Four are scheduled to be released by this week, one remains in care, and the rest have died. Four have been confirmed victims of domoic acid poisoning, and lab results are still out on the rest.

Caron, whose lab conducts the testing, said, “Over the eight years we have seen an increase in frequency and severity in these toxic blooms. In 2007 there was double the concentration of domoic acid in the samples we saw, as compared to the samples from 2003. Last month we got samples from the San Pedro Channel that were double those numbers from 2007.”

The number of animals coming into the mammal center with domoic acid poisoning has fluctuated between 10 and 29 per year, with spikes of 52 in 2007, and 125 in 2002, the year before Caron started keeping track. The cause of harmful algal blooms is complicated, and with data on Pseudo-nitzchia unavailable before 2003 long term patterns are not established.



“I don’t think 2003 was the first time we’ve seen D.A. I think it’s the first time we recognized it,” said Caron, referring to domoic acid.

Determining the cause of domoic acid is difficult. Said Caron, “A complex set of conditions has to give rise to the growth of a specific type of algae, then once it grows, it has to be in a physiological disposition to produce domoic acid, which might depend on a whole other set of conditions coming into play. It might not be an absolute level of a single nutrient, but ratios of nutrients present in the water,” and notes that there are thousands of species of phytoplankton that thrive in different conditions.

“We have cycles in the ocean that are decades long, so its difficult to tell if this is here to stay and will always be with us and get worse, or if it is a pulse in a cycle that will change. On top of that there is climate change taking place and there may be a climatic signal in this as well.”

In his 2006 Pulitzer Prize winning series for the Los Angeles Times, “Altered Oceans,” Kenneth Weiss asserts, “Industrial society is overdosing the oceans with basic nutrients.”

Caron said his team has not identified a causal pattern between human activity and harmful algal blooms, noting that they occur in places far from urban runoff, but did admit, “There is every possiblity that our actions on the coast are or will have an impact.”

Domoic acid does not effect elephant seals, as they dive much deeper than harbor seals and sea lions, and prey on different animals, according to Hunter. She has also never seen a harbor seal affected by the poison.

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