Marine Mammals Are Suffering From a Life-Threatening Toxin Off California's Coast
On a gloomy July morning on California’s Central Coast, the holding pens at the Marine Mammal Center’s Morro Bay facility were filled to capacity. “It’s been a busy month,” said Operations Director Diana Kramer, “And looks like it’s only going to get busier.”
Kramer, a small, energetic woman with light brown hair tucked under a large ball cap, sipped coffee from an insulated cup as her staff of a half-dozen volunteers gathered around to discuss the day’s schedule – rounds of treatments, transport of animals, and the all-but-inevitable rescues. Beyond the facility, the tall smokestacks of the defunct Dynegy Power Plant pierced the low-hanging fog.
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The work of marine mammal rescue groups is yielding critical knowledge about the ocean's complex set of ailments. (photo: Jeremy Miller)
For more than 30 years, this California nonprofit has cared for sick and injured marine mammals – seals and sea lions, mainly – rescued from hundreds of miles of California shoreline. Its 65 permanent staff members and 1,200 volunteers encounter a wide range of ailments – from entanglements in fishing nets and strikes with boats to viral infections and rare cancers.
On this particular day, four of their “patients” were California sea lions. The other was a northern fur seal – a pelagic species typically found in deeper waters off the Channel Islands – rescued from a nearby beach. The animals occupied their pens in a state of lethargy. When they rose from the concrete, their heads waggled oddly or remained cocked backward at tortured angles. One female sea lion, called Eminema, sat motionless for minutes at a time with her head curled back, her neck muscles taut as a bowstring.
All five of these animals were suffering the same condition – domoic acid toxicosis. Excreted by a diatom known as Pseudo-nitzschia, domoic acid is a potent neurotoxin that is taken up by algae-eating fish such as anchovies and sardines. Domoic acid is bio-accumulative, meaning that it tends to be found in highest concentrations in animals at the top of the food chain. Ocean predators such as fur seals and sea lions (which can eat as much as forty pounds of fish a day) are highly vulnerable to its effects. The toxin binds to specific receptors in the hippocampus, a small, seahorse-shaped region of the brain responsible for long-term memory and spatial navigation. The symptoms are memory loss, seizures, and brain damage. In high enough doses, domoic acid is lethal.
Over the last two decades, domoic acid poisoning has been responsible for the strandings and deaths of thousands of pinnipeds along US shores – elephant seals, harbor seals, Guadalupe and northern fur seals. Humpback whales, Brandt’s cormorants, and brown pelicans, among several other species, have also been found dead with high levels of the toxin in their systems.
But California sea lions seem to be bearing the brunt of the problem. Since 1991, the National Oceanic and Atmospheric Administration (noaa) has declared six “unusual mortality events,” or umes for California sea lions; three of these mass stranding and die-off events – in 1998, 2000, and 2002 – were linked to domoic acid. (The Marine Mammal Protection Act defines a ume as “a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response.”) While the current ume for California sea lions, issued in 2013, has been linked to declining fish stocks, Kramer stresses that domoic acid remains a critical threat. This July alone, she and her team rescued 68 California sea lions exhibiting signs of domoic acid poisoning.
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Domoic acid poisoning has impacted a range of pinniped species, including elephant seals, harbor seals, and northern fur seals (pictured). (photo: Kristin Wilkinson / NOAA Weather in Focus Photo Contest 2015)
To be sure, domoic acid is just one of a multitude of factors impacting the planet’s ocean life. For example, a 2016 report from the Secretariat of the Convention on Biological Diversity found that more than 800 species worldwide are harmed by ocean debris. Free-floating “ghost” nets claim the lives of tens of millions of animals annually. Even the smallest detritus poses serious threats – microplastics can be ingested by animals at all levels of the marine food chain. Busy shipping lanes near large port cities are growing noisier and more dangerous for migrating cetaceans. In the San Francisco Bay Area, that reality was hammered home in May, when a 79-foot-long blue whale washed up off the shore of Bolinas, California. The necropsy found that the adult whale had sustained shattered ribs and massive fractures to its spine and skull – injuries “indicative of significant blunt force trauma that is consistent with ship strikes.”
And yet, perhaps more than any of these other impacts, domoic acid reminds us of our complex and pervasive influence on the world’s oceans. “This might seem like a problem that’s ‘out there’ happening in the vast ocean,” said Giancarlo Rulli, a spokesperson for the Marine Mammal Center. “But what we see happening with these sea lions and domoic acid has a direct bearing on the cioppino you order at Fisherman’s Wharf.”
In 2015, so-called “red tides” associated with domoic acid (as well as other algae-produced poisons such as saxitoxin and brevetoxin) rolled in on beaches from northern Washington to Southern California, shutting down Dungeness crab and other fisheries up and down the US West Coast. Measurements taken in Monterey Bay in mid-2015 revealed domoic acid concentrations 10 to 30 times higher than normal, according to noaa. In humans, the toxin can cause diarrhea and vomiting and, in rare cases, trigger a bizarre condition called amnesic shellfish poisoning, which can result in permanent loss of short-term memory. Though deaths are rare, domoic acid can also be fatal.
Racked by rising temperatures and increasing concentrations of pollutants, our oceans are in a state of medical emergency. Rescue groups like the Marine Mammal Center are the first responders. Their effort to save hundreds of sick and injured animals each year at the narrow interface between water and land is an act of compassion. But it is more than that. It is a mission yielding critical knowledge about the ocean’s complex set of ailments, as well as insights into human disease. This knowledge, in turn, reinforces an age-old ecological concept: What we do to our planet we ultimately do to ourselves.
There is no antidote for domoic acid other than time and intensive care. Working in groups of two and standing behind tall plywood barriers, Kramer and her team cornered each of the five animals and inserted a subcutaneous needle into their backs. The needles supply a steady drip of Ringer’s solution, beginning the long process of flushing the toxin from their bodies. Some of the animals also received doses of the anti-anxiety drug lorazepam to ease their stress levels, along with injections of phenobarbital to help prevent grand mal seizures commonly associated with domoic acid poisoning.
The sedatives quickly kicked in. Snores and grunts of deep sleep emanated from the pens. Satisfied with the conditions of her patients, Kramer stepped inside the clinic to finalize plans for transport from the central California center to the mmc’s main facility in Sausalito, north of San Francisco. She also looked over a pile of forms, each one a record of the hundreds of calls placed in recent weeks to the mmc’s emergency hotline. A large part of the center’s success, it turns out, is dependent on public vigilance. Each year thousands of calls come in reporting sick or injured marine mammals. Sometimes the calls yield nothing. But often they result in saved lives. In 2016, the mmc rescued 927 animals – an average of close to three animals per day.
Ten or fifteen minutes after the sedatives and anti-seizure drugs were administered, labored grunts and whimpers came from the pen of a large female sea lion called Tater Tot. Her tail flippers were rigid as a plank and twitching rapidly – the unmistakable signs of a seizure.
Kramer checked Tater Tot’s reports, noting that she had not received her round of anti-seizure medication. Kramer and a volunteer administered a dose of phenobarbital. After a few agonizing minutes, the convulsions ceased. The animal’s muscles relaxed. Her dog-like face rested on the pavement, almost serene, as if in a deep slumber.
The Morro Bay facility is equipped only for triage. Tater Tot’s final destination was the mmc’s Sausalito treatment center. After her vitals were stable, volunteers carefully hoisted the 200-plus-pound animal into an ice-cooled crate, which was then loaded onto the bed of a pickup. “Our goal is to make sure each of our patients is stable and secure before transferring them,” Kramer said. “That’s all we can do for her here.”
While rescuers and veterinarians work to save animals harmed by domoic acid, others seek a clearer understanding of the array of factors – both natural and manmade – contributing to the harmful algae blooms from which these toxins originate. In addition to increasing quantities of phosphorous and nitrogen entering the ocean by way of urban and agricultural runoff, scientists believe another key catalyst for the domoic acid outbreak of 2015 (and other severe algal blooms in the past two decades) was warming ocean waters triggered by El Niño. But natural cyclical patterns like El Niño can’t explain all of what’s going on: A recent study from Christopher Gobler, an ecologist at Stony Brook University, found that the active bloom season has been lengthened by more than a month since 1982 – suggesting that rising average ocean temperatures likely linked to anthropogenic warming of the atmosphere may be contributing to larger, longer-lived blooms. “The distribution, frequency, and intensity of these events have increased across the globe, and this study links this expansion to ocean warming in some regions of the North Atlantic and North Pacific Oceans,” Gobler said in a press release.
Through the California Harmful Algal Bloom Monitoring and Alert Program, scientists are creating an online database to better predict where and when these harmful blooms will occur. While scientists are still trying to tease out the patterns, it seems that the blooms tend to unfold successively, in a northward direction – in warmer waters along the Southern California coast early in the season and spreading northward as ocean temperatures rise during the summer months.
Others are looking at the mosaic of individual cases that indicate an outbreak and can give a sense of the overall health of a species. One promising endeavor being undertaken by the Marine Mammal Commission, an independent federal agency, is the creation of a real-time online system for collecting data on marine mammal health. Known as the Marine Mammal Health Monitoring and Analysis Platform – map for short – it will provide an easy-to-use, online map showing the distribution of strandings (gathered from rescue groups like the Marine Mammal Center) along with information about their causes.
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Information gathered by rescue groups like Marine Mammal Center can provide valuable information about the health of the ocean. (photo: Jeremy Miller)
“Marine mammals serve as really good indicators for the health of the ocean,” said Samantha Simmons, acting scientific program director for the Marine Mammal Commission. “Having robust populations of marine predators usually means that you have robust marine ecosystems.” Moreover, she explained, the health of marine mammals is a valuable proxy for human health. “We have a lot in common with marine mammals. We eat a lot of the same things from the ocean that they do. When we use the ocean recreationally, we’re often in the same habitats that they are in.”
When finished, Simmons said, the map will provide a powerful tool to scientists, policymakers, and the general public – a kind of Centers for Disease Control clearinghouse of data about marine mammals. “Our goal is to gather information from across regions and across species,” she said. “We are making that available to the public in a standardized form while also making it available to researchers and stranding network responders.”
Simmons said the system could be completed within a year-and-a-half. The major hold-up at this point is financial. “Right now the federal budget is not conducive to these sorts of expenditures,” she said, reflecting a common anxiety these days under the Trump administration, particularly among federal agencies tasked with protecting the environment. “We’re looking lots of places for funding. Primarily, I think it will end up coming from the private sector.”
Thirty minutes north of downtown San Francisco, the Marine Mammal Center’s main treatment facility, near Sausalito, sprawls over several acres on a hillside commanding a dramatic view of the Pacific Ocean. The facility is one of the largest marine mammal hospitals in the world and is capable of treating more than 200 animals at a time.
On the day of my visit, a menagerie of harbor seals, elephant seals, and California sea lions populated the fenced enclosures. The strange, almost alien barks of a pair of young Guadalupe fur seals – hunted nearly to extinction in the late 1800s – echoed through the grounds.
Like the Morro Bay facility, the bulk of the animals were California sea lions suffering from domoic acid poisoning. As we walked through a conference room, Giancarlo Rulli pointed out a marker board. It was a manifest of newly admitted animals. The most recent group of five or six sea lions brought in from the Central Coast in the previous days all had the words euthanized and died in transit written beside them.
Rulli told me that in domoic acid cases the historic rate of recovery stands at about 50 percent – a coin flip. (Last year, 411 of the animals taken into the mmc’s care were eventually released back into the wild; meanwhile 471 died in transit or care, or had to be euthanized.) “If they come in chronic, the outlook is not good,” he said. “But if we can get them during the acute stages and start flushing the toxins right away, the outlook improves dramatically.”
Animals that endure the primary symptoms of domoic acid poisoning, however, often face serious secondary complications. For example, conservation medicine veterinarian Claire Simeone has seen dozens of animals with eye trauma during her four years at the center. When a sea lion has a seizure while swimming there’s a high probability of drowning. But even when the seizures happen on land the animal still faces significant dangers. As their bodies thrash and convulse, muscle contractions can cause their eyes to lock open, making their corneas vulnerable to scrapes and ulcers from rocks and sand.
Repeated treatments with eye drops can cause stress and pose risks of serious injury to an animal, said Simeone. So for the last couple of years she has been testing a new kind of gel that can be applied just once with the animal under anesthesia. “With wild animals, we want to be as hands off as possible,” she added. The results of the trial have been exceedingly positive. “We found that 100 percent of the superficial ulcers, the basic scratches, healed with just one gel treatment,” Simeone said.
Simeone demonstrated the procedure by re-examining a young female called Ghost Towne who had come to the facility two weeks earlier suffering from corneal ulcers. After just one round of treatment, Simeone said she appeared to be recovering well from her eye injuries.
Injured wild animals can be very aggressive, she noted. Treatment, therefore, is a carefully orchestrated dance, one requiring a careful observance of protocols meant to reduce risks to workers and animals alike. Using wooden barriers, the team cornered the animal then placed a sack-like net over her head. Once the net was secure, one technician held down the animal’s rear flippers while another straddled the animal’s upper back and head. Then they administered an anesthetic gas through a hose and a hood resembling an orange traffic cone.
As her body went slack Simeone tied open Ghost Towne’s jaws and slid a breathing tube into her mouth, stroking her head gently with hands covered in colorful latex gloves. Simeone knelt beside the motionless animal, propping open her lids with a metal clip. Then she squirted a dash of solution from a syringe into the animal’s goggle-like eye, which she inspected with a scope. The cornea was clear of abrasions.
The group of volunteers, many of whom were veterinary school students from various universities around the country, expressed happiness as they prepared to revive her – even hinting that a release could be imminent. But just then, they noticed a strange bump in one of her front appendages. Simeone prodded the animal’s right front flipper with a gloved hand and gave a grim assessment: “Looks like she’s got a separated elbow,” she said.
The medical staff rushed the animal into the facility’s x-ray room and huddled around a digital display. The injury proved to be more severe than expected – in addition to the dislocation the group suspected a fracture. After a swift consultation with staff veterinarian Cara Field, the group determined that little could be done (and with the increasing numbers of animals coming in, space in the holding pens was at a premium). While sea lions can live full lives with disabled rear flippers, Field said, severely injured front flippers are a virtual death sentence. Sea lions use their front appendages much in the way a boat uses a rudder. These limbs are critical not only for locomotion on land but to make sudden changes of direction in the water as they pursue fish or evade predators. “If this was a very young small animal that is still growing, there is maybe some potential for an injury like this to heal,” said Field. “But with an older animal that is much bigger and heavier, there is just no way to immobilize [the joint].” The team decided the only humane course of action was to euthanize her.
Tragic as the death of any animal seems, Field noted that science would benefit from Ghost Towne’s death. Her body was immediately carted to the necropsy room where Barbie Halaska, the center’s research assistant, would take tissue samples of her brain.
Halaska, who during this latest domoic acid outbreak was performing as many as two-dozen necropsies a week, said the work has yielded important insights into the effects of domoic acid. In serious cases, the hippocampi of the affected animals have dwindled to half – even a third – of their original size. In addition to loss of spatial sense and memory, this mass atrophy of brain tissue can lead to an impaired sense of smell, which is critical in maternal care among sea lions. “Females will smell their pups when they are first born, which is important for bonding,” said Halaska. “In some females with domoic acid poisoning their sense of smell is inhibited and they might not bond with their pups.” As well as neurological impacts, domoic acid can severely impair heart function.
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Since 2013, more than 5,000 malnourished sea lion pups have been found stranded on California beaches. The strandings have been linked to declining fish stocks, and, possibly, domoic acid poisoning. (photo: Tracey Rabjohns)
Beyond the benefits to marine mammal medicine, said Halaska, their research is yielding important understandings into human disease. One Stanford researcher they are collaborating with is using the sea lion tissue to better understand human epilepsy. “Their domoic acid seizures are very similar to temporal lobe epilepsy seizures,” she said. Which is to say, through painstaking study of intelligent mammals such as sea lions we are gaining profound insights into our inner workings – and, perhaps, if we read the signs carefully enough, our own prospects for long-term survival.
Here, at the story’s end, I have a confession to make. In conceiving of this article, I already had the ending written in my mind. The scene was simple: A sea lion tramping triumphantly over the sand back toward the waves and the ocean from whence it came – a perfect three act tale of rescue, recovery, and release.
As my deadline approached, however, Giancarlo Rulli left an apologetic message on my phone. He said that none of the animals in the facility were ready for release. “I’m sorry, but there is no set schedule for these things,” he said. Out of curiosity, I checked the online list of animals admitted to the mmc’s main facility in Sausalito, wondering if Tater Tot, the female sea lion I saw suffer a major seizure in Morro Bay days earlier had made it. Her companions, Deming and Cat were listed. So, too, was Eminema and Orpheus the northern fur seal. But Tater Tot was not on the list. She had succumbed to the poison and was euthanized. A coin flip.
And yet, the animals that do not recover are as instructive, I think, as those that do. Each injury, illness, and death caused or complicated by human factors underscores the terrible efficiency with which we are unraveling the delicate web of the ocean’s ecosystems. Conversely, every rescue and treatment highlights a growing sense of responsibility to counteract that damage. It’s an exercise of long odds – of dedication, fortitude and, most critically, deep reverence for the natural world. It’s driven by a sense that these animals are not merely “sentinels” or “indicators of ocean health” but compatriots on this one ailing planet. It’s the sort of work on which our future depends.