When millions of sardines swam to their death in Redondo Beach’s King Harbor Marina in March and dozens of convulsing sea lions struggled ashore in Hermosa Beach in April, researchers found a common thread: Domoic acid was in their systems.
The presence of domoic acid in the ocean waters of Southern California isn’t new. It’s a naturally occurring nerve toxin produced by algae blooms, mostly during the months of March to June.
But researchers say they are concerned about what appears to be a troubling trend—levels of domoic acid are sickening or killing increasing numbers of Pacific Ocean marine animals along the West Coast, particularly in a “hot zone” stretching from California’s Ventura County to the South Bay.
“Some years are much more severe than others,” said Cindy Reyes, executive director of the California Wildlife Center, a Malibu, CA-based nonprofit that rescues and rehabilitates native wildlife.
The number of animals suspected of suffering domoic acid poisoning that the center has rescued fluctuates from year to year, often because of changing weather conditions.
The center first began tracking cases of suspected domoic acid poisoning in 2005, when it rescued 39 California sea lions exhibiting symptoms. In 2006, the center rescued 15 sea lions and a long-beaked common dolphin; in 2007, 45 sea lions and three dolphins; in 2008, 24 sea lions and a northern elephant seal; in 2009, 18 sea lions; in 2010, 29 sea lions; and then this year, 15 sea lions as of April 30.
At the Pacific Marine Mammal Center in Laguna Beach, CA, 25 animals were suspected domoic acid poisoning rescues in 2003; in 2004, 29; in 2005, 17; in 2006, 27; in 2007, 52; in 2008, 10.
The center didn’t record numbers for 2009 and 2010, but this year, 27 rescued sea lions and eight common dolphins were suspected of having domoic acid poisoning, said Michele Hunter, director of operations and animal care at the center.
Between the two centers, at least 50 animals suspected of domoic acid poisoning have been rescued this year. Some local researchers predict that in the coming years, more animals are going to be affected.
“In my mind, it’s only going to get worse,” Reyes said.
Pseudonitzchia is the genus name for the algae that produces domoic acid. The springtime warming of ocean water near the surface usually triggers its annual bloom.
Its levels can be influenced by weather conditions and the presence of nutrients produced either by natural sources or pollution.
Based on her observations, Reyes said, runoff from heavy rains this year contributed to the creation of a “toxic stew” that promoted the rapid growth of algae blooms.
This “abnormally large” bloom has led to the negative effects seen recently in Southern California, said Alisa Schulman-Janiger, an American Cetacean Society researcher.
Strong winds have also pushed blooms to the coast, she said, causing a greater impact on fish, sea lions and birds.
When the toxin is produced, it works its way up the food chain. Plankton first absorb the toxic algae. Sardines and other fish eat the plankton, causing the domoic acid to concentrate in their bellies. Sea lions and common dolphins eat the fish, and the toxin builds up in their systems to potentially lethal levels.
Schulman-Janiger said that domoic acid mostly impacts pregnant female California sea lions, who tend to consume much more food than other sea lions.
“What happens with them [is] they get epilepsy, and they’ll come up on land and act really strange,” she said. “Most are pregnant this time of year, not ready to give birth until, say, June … they’re miscarrying and the babies are dying.”
Other affected animals include common dolphins. More than a dozen dead or dying common dolphins have washed up from Orange County to Malibu in the past few months.
A necropsy performed on one of the dead dolphins detected domoic acid in its blood and other body fluids, Reyes said.
“We’re pretty confident animals [near Malibu] were definitely dying from this domoic acid exposure,” she said.
Researchers don’t know which pollutants or natural occurrences may promote higher levels of the toxic blooms, and why more frequent and more severe blooms appear to be occurring. But the National Oceanic and Atmospheric Administration is funding research in an attempt to find an answer.
NOAA’s funding comes from the Harmful Algal Bloom and Hypoxia Research and Control Act, which was passed by Congress in 1998 (and reauthorized in 2004) following reports of mass strandings and deaths of sea mammals in the 1990s.
The goal of the research is to improve researchers’ abilities to detect, assess, predict, control and mitigate toxic blooms, said Marc Suddleson, NOAA program manager for the Monitoring and Event Response for Harmful Algal Blooms (MERHAB) research program.
“We’re really trying to better understand what makes [toxic algae] bloom and when,” Suddleson said. “This is a national problem and we are constantly putting out new programs to move forward.”
Other programs funded by NOAA are the Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) and the Prevention, Control and Mitigation of Harmful Algal Blooms (PCMHAB) research programs.
Because of these recent research projects, “California is now in a much better position to reach that end goal of predictive capability,” Suddleson said.
Studies at the University of California, Santa Cruz, and a project named RAPDALERT at the University of Southern California, spearheaded by biology professor David Caron, are funded under Suddleson’s program.
“These region projects have already laid amazing foundation for the state to build off of… and further research goals with new tools as well as new modeling of the ocean and environment to better understand blooms,” Suddleson said.
Caron, who has been researching domoic acid’s effects on local marine life since 2003, has focused primarily on “trying to understand why certain types of algae come and go and what that means for the overall function of the system,” he said.
“We’re not just interested in harmful algal blooms, but they provide an interesting experiment for us because they come in and dominate the system from time-to-time and we want to understand how they do that,” he said.
In the first case of domoic acid poisoning that Caron and his team studied, they consulted with a representative of the Natural History Museum of Los Angeles County.
“I said, ‘I can’t believe this is the first we ever had domoic acid here,’” Caron recalled. “And he said, ‘You know, we’ve had a mortality event in the 1990s and didn’t know what that was. It could have been a domoic acid event.’”
Caron said that his team had access to the museum’s specimens from that event and looked for the toxin, but couldn’t detect any.
“So it might have degraded by then,” Caron said. “[But] we have seen these events occur in the past and they just went under the radar.”
Even coastal residents have noticed events for over a decade that, while at the time were from unknown causes, now appear to share characteristics of domoic acid poisoning.
“I can remember sea lions coming ashore sick almost every year,” said Torrance, CA-based fisherman and Patch contributor Philip Friedman, who has had an eye on Southern California waters for years. “My sons and I came upon a really sick sea lion at Abalone Cove [in] 1999. It was completely disoriented and sick.”
Caron likened the emergence of domoic acid awareness to what happens when medical researchers identify the characteristics of certain diseases.
“When Lyme disease was discovered in the U.S., as soon as they knew what to look for, it showed up everywhere because people said, ‘Ah, that’s what we look for,’” Caron said. “So it’s this emerging awareness to help us recognize what’s existing already in the environment.”
Now that researchers and animal rescue centers are aware of domoic acid’s presence in the ocean, “I don’t get a call anymore that [says], ‘We’ve got an animal that’s acting weird,’” Caron said. “We get a call that says, ‘We’ve got an animal that’s exhibiting symptoms of domoic acid.’”
Caron’s team works with rescue centers to give them notice as to when they can expect toxic blooms to occur.
When a rescue center recovers an animal with domoic acid poisoning, its staff typically gives the animal fluids, which allows the animal to process the food that caused the poisoning and then excrete the toxin, Reyes said. Medication also is often administered.
Once animals are rehabilitated, most centers release them back into the ocean. The Marine Mammal Care Center in San Pedro, CA for example, releases animals near the Palos Verdes Peninsula.
Most local centers take body fluids and other samples from animals that have exhibited domoic acid poisoning and provide them to scientists, such as Caron’s team, for research.
Caron’s team also now has sensors in King Harbor in Redondo Beach that monitor the oxygen level and toxicity of the water every half hour.
The sensors allowed Caron’s team to confirm that a lack of oxygen caused about 175 tons of sardines to die in Redondo Beach’s King Harbor Marina in March, as the sensors showed that toxicity levels were normal, but oxygen levels were significantly low.
When the dead fish were later analyzed, domoic acid was found in their bodies, which could indicate that they swam through blooms on their way to the marina, Caron said.
And even though some scientists contend that domoic acid doesn’t affect fish as it affects the neurological systems of sea mammals, Caron thinks more research into its impacts on fish behavior could be worthwhile. For one thing, he doesn’t understand why the sardines in Redondo Beach didn’t sense the lowering oxygen levels in King Harbor and flee into open waters, as he would have expected.
Because the coastline in the Greater Los Angeles region has been named a “hot zone” for toxic blooms, some people, like local fisherman Friedman, suspect that urban runoff and other forms of pollution provide nutrients that intensify toxic algal blooms.
This cause-and-effect assumption has not been confirmed through scientific research, Caron said, noting that natural sources of nutrients for toxic blooms could also be a factor.
“The big question is what is the relative importance … of the natural sources of nutrients versus the human-activity-derived nutrients,” Caron said. “What are the sources of nutrients that give rise to these toxic algae blooms?”
“Even with 10 years of information, we have a relatively short timeline on this problem, and this is something we need to follow,” Caron said. “We need to see if we’re seeing increases in a linear fashion…. Is it something that’s coming and won’t go away? It’s very difficult to tell the long-term trends when you have a short-term data set.
“What I can tell you is that, so far, we see no wane in this.”
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See accompanying video under photos for Southern California residents’ reactions to the impact domoic acid has had on local wildlife.