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On Calif. coast, biotoxins cause deadly sea lion seizures, seafood scare

An outbreak of algae-produced biotoxins that attack animals'€™ brains also poses a grave risk to humans

MORRO BAY, Calif. – Packed with large nets, wooden boards and a large crate, a dark blue truck scoured the edges of surfer-lined Pismo Beach late one morning earlier this month. Onlookers in the distance tipped them off to what they were searching for.

“I see a sea lion,” said Geno DeRango, the stranding coordinator at Marine Mammal Center's San Luis Obispo Operations, as he quickly slipped on medical rubber gloves and began prepping a large syringe.

The truck came to a halt and the rest of DeRango’s crew suited up for the rescue – wooden boards in hand, two crew members crowded around a disoriented sea lion convulsing on the edge of the water while DeRango threw a net over it. The fourth crew member injected the sea lion with an anti-seizure medication before herding the animal into a large crate and loading it on the bed of the truck.

Concerned onlookers asked what happened to the sea lion as they took turns peering into the back of the truck. Heavy breaths and sounds of suffering bellowed from the cage.

DeRango explained that the rescue center got a call about a sea lion having repeated seizures on the beach and that they were taking the animal back to their rehabilitation center.

Peppa, the name given to the rescued sea lion, is like many of the animals crowding the six pens at the rescue center, which has brought in as many as 20 seizing sea lions a day in the San Luis Obispo area since June. Earlier this spring, its partner rescue center in Monterey experienced a similar boom. Of those rescued at both sites, half succumb to the seizures within days.

The culprit? Domoic acid, a deadly neurotoxin produced by algae, that appeared at record high levels along California’s Central Coast this spring and summer, closing fisheries and taking the lives of many marine mammals. But toxic algae isn’t just limited to California-- this summer various toxic blooms have poisoned coastlines across America, including Lake Erie and the Gulf of Mexico.

The genesis of domoic acid

While the algae in Monterey, produced by the Pseudo-nitzschia genus of phytoplankton, are a common occurrence along the Atlantic and Pacific coastlines and around the world, its production of domoic acid is not.

First discovered in 1987 when 107 people on Prince Edward Island fell ill after eating mussels harboring domoic acid, the algae occasionally produce this deadly toxin, which scientists believe is triggered by changing ocean conditions and surges of nitrogen into bodies of water.

Once produced by the algae, domoic acid quickly works its way up the food chain, first gobbled up by shellfish and plankton-eating fish, like sardines and anchovies, that harbor the toxin in their guts. Next in line are sea lions, brown pelicans, otters, whales and dolphins, all of which have been stranding in large numbers recently, or, in the case of pelicans, literally dropping dead out of the sky.

Once ingested, the toxin immediately attacks the brain by rapidly shrinking the hippocampus, causing loss of motor coordination, amnesia, violent seizures, vomiting, permanent neurological damage and even heart failure within two days.

But domoic acid also poses a grave risk to humans, which is why the California Department of Public Health closed certain fisheries up the coast in Monterey and Santa Cruz counties in April after high levels of the acid were reported by a team of marine scientists at University of California, Santa Cruz, that has been monitoring domoic acid for 14 years.

“The danger lies in the accumulation,” said Clarissa Anderson, one of the marine scientists in Santa Cruz tracking the growth of domoic acid events. “It's not horribly toxic unless it accumulates at high levels.”

But Anderson says that concentrations reached dangerously high levels this spring all over the California coast, particularly in Monterey.

Monterey is the top agricultural area along the Central Coast as well as home to a suite of premier golf courses. It’s also been subject to a large coastal population boom, meaning more septic tanks and more lawns being fertilized. Combined, says Anderson, these activities result in more nitrogen running off into the Bay, altering the marine environment in a way that can lead to higher domoic acid concentrations.

Seasonal upwellings of ocean waters flush the Bay with nutrients, which could naturally trigger the algae to produce these blooms. But those upwellings usually diminish quickly, as do the nutrients that feed toxic blooms. However, constant pulses of nutrients coming from human activities, mostly from fertilizer application, allow the toxic blooms to persist.

Nationwide, agriculture is the top source of nitrogen added to water resources, and California is no different. The amount of nitrogen contained in fertilizer sold in California has increased by 800 percent since the 1940s, contributing to the hefty 800,000 tons of nitrogen used as fertilizer every year.

Up and down the coast

Even further up the coast, north of San Francisco, the aftermath of this rising nitrogen use has been unfolding at The Marine Mammal Center headquarters in Sausalito.

“These blooms are getting more frequent and larger every year and affecting more and more animals,” said Shawn Johnson, director of veterinary science at The Marine Mammal Center.

As the largest marine mammal hospital in the world, the Marine Mammal Center receives hundreds and hundreds of seals, sea lions and elephant seals every year, many of which are rescued from their satellite centers in Morro Bay and Monterey, as well as from independent rescue centers along the Pacific Coast.

But this year has been different.

“There are a lot of animals are being exposed to such high levels of domoic acid, that they’re dying on us. They're not responding to treatment like they often have in the past,” Johnson said.

The Center has broken its animal admissions record this year, and the number of sea lions suffering from domoic acid has roughly doubled. But that number doesn’t include all of the sea lions that die before washing ashore, Johnson said. Nor does it account for all of the sea lion pups that will likely die without a parent. Many of the afflicted sea lions are lactating females still weaning their pups.

The danger lies in the accumulation.

Clarissa Anderson

Marine scientist

“If there are a few hundred or even a thousand sea lions affected by domoic acid right now, well there's a few thousand pups that we're probably losing,” Johnson said. “If this is happening over and over again, year after year, there is a fear that domoic acid may have a negative impact on the overall sea lion population.”

On July 11, the California Department of Public Health lifted its seafood advisory for Monterey and Santa Cruz Counties after combined monitoring efforts with Anderson’s team found levels had dropped back down to ones safe for human consumption. However the renewed surge in marine mammal strandings has left scientists puzzled.

“A lot of the animals that are stranding right now don’t tend to feed very far off shore,” Anderson said. “So the mystery is, where is the domoic acid that they’re acquiring? We’re not measuring it in the mussels and shellfish near shore.” 

More research needed

In California, marine scientists are seeing more and more animals, like sea lions, affected by high levels of domoic acid.
In California, marine scientists are seeing more and more animals, like sea lions, affected by high levels of domoic acid.
America Tonight

Part of the problem is that monitoring of domoic acid is limited to wharfs close to shore, but the fish harboring the toxins – and the algae producing the toxic blooms – may be living just offshore, where sampling tends to be either too expensive or too technically difficult to do regularly.

While Anderson believes that the Department of Public Health is doing a good job protecting humans from danger (no human illnesses have been reported this year), she thinks that more could be done to stop the sources of the problem.

“The California State Water Resources Control Board is doing a lot, but they are certainly susceptible to pressures of all the different interest groups that are involved,” she said.

The California State Water Board limits the amount of pesticides, nutrients and other pollutants discharged into surface and groundwater. While it has strict reporting requirements for pollutants like pesticides, nutrient reporting is interpretive and a 100-percent reporting system for agricultural fertilizer use has yet to be implemented.

Part of the reason why nutrient reporting is lacking is because determining the correct level of nutrients for water systems is very complex, said Rik Rasmussen, the fresh water quality standard program manager for the State of California.

“It's not a simple thing as saying 10 is the right number. Or one is the right number, or zero is the right number,” said Rasmussen. “If we don’t have nutrients, we don't have life.”

While nitrogen, phosphorous and potassium – three common ingredients in fertilizer – are the backbone of life, finding the right balance is tricky since every body of water reacts differently to nutrients, Rasmussen said.

This becomes even more of an uphill battle during drought. In years of low snowpack like in 2014, rivers and streams become warmer and run slower in the spring due little snow melt, which increases a water body’s sensitivity to additions of nitrogen. This then becomes even more complicated during El Nino, as is predicted to hit this fall, as heavy rainfall will likely sweep accumulated fertilizer from drought-stricken lands into nitrogen-sensitive waters.

“It’s a harder job for our scientists and engineers to write the correct levels in permits because it varies depending on the water body,” Rasmussen said.

So as regulators fine-tune the rules, and scientists try to crack the mystery of where the toxic algae are blooming, marine mammals continue to suffer.

Peppa, the sea lion rescued on Pismo Beach, succumbed to her violent seizures only three hours after her rescue. Cause of death: a severe dose of domoic acid toxicosis. Peppa was also found to be nursing.

“From being on the front lines and seeing how it affects negatively these animals, my biggest fear is if this happens all the time or if it's everywhere on the West Coast,” Johnson said. “And if that happens, it's going to affect all the fish and it's going to close down fisheries and it'll have a huge negative impact on everyone.”

Both Johnson and Anderson agree that research will be the key to better understand and prevent toxic blooms, which are anticipated to cost the U.S. up to $50 million each year in cleanup and job loss. But Anderson said what’s needed first is more funding for that research and more federal and state action.

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