The central California coast is experiencing harmful algae blooms that produce the toxin domoic acid, a threat to sea lions and other marine life.
September 10, 2013
It's always great when a story has a happy ending, and such was the
case with Perfume, a California sea lion who was one of a number of sea
lions being treated for domoic acid toxicity at The Marine Mammal Center
over the past few weeks. Perfume was released back to the ocean on
Saturday, September 7, at Scotty Creek Beach near Bodega Bay. A crowd of
onlookers and well wishers watched as she joyously made her way back
home.

Perfume returns home to the ocean, at Scotty Creek Beach in Sonoma County
September 5, 2013
Currently, The Marine Mammal Center has a large number of patients
affected by domoic acid: Marilou, Vuronica, Shia, Perfume, Lumi,
Surfer, Jerika, Late Night, Bautista, and Whirley. Several others have
been released following successful treatment, and two have died during
treatment. These patients, all of them California sea lions, were
rescued in the past few weeks along the San Luis Obispo and Santa
Barbara County coast.
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Perfume is a California sea lion who was rescued in San Luis Obispo County, suffering from domoic acid toxicity (acute)
© The Marine Mammal Center
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What is domoic acid?Domoic acid is a neurotoxin
associated with algal blooms which can have serious effects on marine
mammals and humans when it gets into the food chain. It was first
discovered in the red algae known as "doumoi" in Japanese, hence the
origin of the name, although this algae is not traditionally related to
the toxicities that we see. Domoic acid is often referred to as “red
tide,” although this is a misnomer, since the algae is often colorless,
or has colors other than red. It is also not typically associated with
the movement of the tides. Scientists prefer the term “harmful algal
bloom.”
Domoic acid is produced by the algae
Pseudo-nitzschia and
accumulates in shellfish, sardines, and anchovies. These fish are then
eaten by sea lions, otters, cetaceans, and humans, among others. If
consumed in significant quantities, domoic acid can cause seizures and
other central nervous problems. Exposure to the biotoxin affects the
brain, causing those affected to become lethargic and disoriented. In
humans, domoic acid toxicity manifests itself as “Amnesic Shellfish
Poisoning,” which can cause short-term memory loss, brain damage, and
even death in some cases.

Shia is another California sea lion patient suffering from domoic acid toxicity (acute)
© The Marine Mammal Center
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Diagnosis of domoic acid toxicity is based on clinical signs and the known presence of Pseudo-nitzschia
algae in the environment. The toxin itself is often long gone from the
animals by the time they are examined. The Center’s researchers
diagnosed the first case of domoic acid toxicosis in marine mammals in
1998, and have conducted extensive studies of the condition since then.
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Why is this information so important? Marine
mammals are like canaries in the coal mine - they warn us of
potentially serious environmental conditions in the ocean that can
affect not only marine mammals, but humans and other animals as well.
This information also provides critical data for scientists
conducting research on global health, and it contributes vital
information to resource managers who monitor human activities that
impact marine mammals in the area. Equally important, it provides
substantive evidence to help inspire protection and conservation of the
ocean and those creatures that call it home.
What causes harmful algal blooms?No one knows for sure, but
Pseudo-nitzschia
(and most microorganisms, for that matter) really like nitrogenous
waste products/nitrates, and other fertilizers (being plants of a
sort). There are a lot of maps that show algal blooms forming at major
river mouths or other waste outfall areas. Also, when the algal cells
die or are consumed by animals, domoic acid is released. Thus there is
ample evidence that human activity can lead to worsening blooms of
harmful algae and affect the health of our sea lion patients.

Phytoplankton monitoring carried out by the CDPH Marine Biotoxin Monitoring Program along the California coast
© California Department of Public Health
The California Department of Public Health website currently shows that
Pseudo-nitzschia
is common or abundant at every phytoplankton sampling site throughout
the 600-mile rescue range covered by The Marine Mammal Center. However,
high concentrations of
Pseudo-nitzschia do not always mean high
levels of domoic acid are present because phytoplankton don’t always
produce the toxin. So sometimes there are Pseudo-nitzschia blooms
without any increase in sea lions stranding with domoic acid toxicity.
Since the first sea lions affected by these blooms began coming into
The Marine Mammal Center about two weeks ago, we’ve noticed that the
more recently rescued animals are showing more intense symptoms. The
puzzle confronting our veterinarians is why the severity is increasing.
They are trying to determine if it is caused by a longer exposure time,
an increasing amount of toxin in the water, or simply that these
particular animals had previously been exposed to the toxin and are now
experiencing an acute poisoning, with the combination of previous
exposures causing more severe illness.
Stay tuned as our research and veterinary science teams learn more.
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