By Kenneth R. Weiss, Times Staff Writer
July 31, 2006
Sentinels Under Attack
Toxic algae that poison the brain have caused strandings
and mass die-offs of marine mammals — barometers of
the sea's health.
SAN FRANCISCO -- After the last patient
of the day walked out the front of Raytel Medical Imaging
clinic, veterinarian Frances Gulland slipped an oversized
animal crate through the back door.
Inside was a California sea lion. The animal
was emaciated, disoriented and suffering from seizures.
A female with silky, caramel-colored fur,
wide-set eyes and long whiskers, she was named Neuschwander,
after the lifeguard who had found her six weeks earlier,
comatose and trembling under a pier at Avila Beach near
San Luis Obispo.
Taken to the Marine Mammal Center near
Sausalito, Neuschwander showed signs of recovery at first.
Her eyes began to clear and focus. She frolicked in the
small pool in her chain-link enclosure and wolfed down mackerel
at feedings. Then she relapsed.
She quit eating and lost 40 pounds. Her
sunken eyes darted around, as if tracking a phantom just
outside the cage. Her head bobbed and weaved in erratic
Neuschwander was loaded into a crate at the nonprofit center,
the world's busiest hospital dedicated to the care of wild
marine mammals, and trucked across the Golden Gate Bridge.
Gulland, the center's director of veterinary science, wanted
to scan Neuschwander's brain at the imaging clinic.
After sedating the sea lion, Gulland and
four assistants lifted the animal onto a gurney. They inserted
a breathing tube into her throat and rolled the gurney into
the great thrumming MRI machine.
Gulland, an upbeat, 46-year-old native
of Britain, took a last look at Neuschwander as the machine
closed around her. She hoped the sea lion could be saved.
Neuschwander was exhibiting the classic
symptoms of domoic acid poisoning, a condition that scrambles
the brains of marine mammals and causes them to wash ashore
in California as predictably as the spring tides.
They pick up the acid by eating anchovies
and sardines that have fed on toxic algae. Although the
algae have been around for eons, they have bloomed with
extraordinary intensity along the Pacific coast for the
last eight years.
The blooms are part of a worldwide pattern
of oceanic changes that scientists attribute to warming
waters, excessive fishing, and a torrent of nutrients unleashed
by farming, deforestation and urban development.
The explosion of harmful algae has caused
toxins to move through the food chain and concentrate in
the dietary staples of marine mammals.
For the last 25 years, the federal government
has tracked a steady upswing in beach strandings and mass
die-offs of whales, dolphins and other ocean mammals on
More than 14,000 seals, sea lions and dolphins
have landed sick or dead along the California shoreline
in the last decade. So have more than 650 gray whales along
the West Coast.
In Maine two years ago, 800 harbor seals,
all adults with no obvious injuries, washed up dead, and
in Florida the carcasses of hundreds of manatees have been
found in mangrove forests and on beaches.
The surge in mortality has coincided with
what Florida wildlife pathologist Greg Bossart calls a "pandemic"
of algae and bacteria. Although some of the deaths defy
easy explanation, telltale biotoxins have turned up in urine,
blood, brains and other tissue.
Sometimes the toxins kill animals outright,
such as the manatees found dead in Florida, blood streaming
from their noses.
In other cases, they kill slowly by promoting
tumor growth or compromising immune systems, leaving marine
mammals vulnerable to parasites, viruses or bacteria. Scientists
believe the episodic die-offs of bottlenose dolphins along
the Atlantic and Gulf coasts that began in the late 1980s
may stem from toxic algae that weaken the animals and enable
a virus related to canine distemper to attack the lungs
Sea turtles in Hawaii have been found with
fist-sized tumors growing out of their eyes and mouths and
behind their flippers. Scientists say the growths are the
result of a papilloma virus and an ancient microorganism
called Lyngbya majuscula, which appears as a hairy weed
that has been spreading in tropical and subtropical waters.
The tumors doom the turtles by inhibiting their ability
to see, eat or swim.
As they watch the oceans disgorge more
dead and dying creatures, scientists have come to a disquieting
realization: The proliferation of algae, bacteria and other
microbes is making the oceans less hospitable to advanced
forms of life — those animals most like humans.
"Marine mammals share our waters,
eat some of the food we eat and get some of the same diseases
we get," said Paul Sandifer, chief scientist for the
Oceans and Human Health Initiative of the National Oceanic
and Atmospheric Administration.
"If environmental conditions are not
good for these sentinels of the sea, you can believe it
won't be good for us either," Sandifer said. "What
we allow to flow into the sea will come back to bite us.
You can bet on it."
Marine algae, or phytoplankton, occur naturally and make
up the first link in the oceanic food chain. A quart of
seawater typically contains hundreds of thousands of phytoplankton
and millions of bacteria, viruses and protozoans, all in
concentrations that keep each other in check.
That equilibrium can be upset when certain
types of algae overwhelm their competitors. The change is
most pronounced in coastal waters, and scientists believe
it is tied to nutrient pollution from a variety of human
Toxic algae thrive on the same elements
that turn lawns green and make crops grow — nitrogen,
phosphorus and iron.
California, the nation's most populous
state with more than 36 million people, sends billions of
gallons of partially treated human waste into the ocean
every day. Sewage treatment cuts down on disease-causing
bacteria but does little to remove nutrients.
Seasonal rains carry enormous loads of
urban and agricultural runoff into the ocean, much of it
down drainage canals and rivers from the dairies, orchards
and farms that make California the nation's largest agricultural
The destruction of coastal wetlands, which
filter nitrogen and other nutrients, also plays a role,
as does over-harvesting of shellfish and sardines, menhaden
and other algae-eating fish.
Climate change is another factor. Warmer
seawater speeds up microbial growth and allows aggressive
algae and bacteria to move into areas once too cold for
them. Commercial ships can help the spread, transporting
the algae in ballast water.
The type of algae that poisoned Neuschwander
began blooming riotously in California waters in 1998.
It has the tongue-twisting name Pseudo-nitzschia
(SUE-doh NICH-e-yah). A fraction of the thickness of a human
hair, this javelin-shaped, single-cell organism slides through
seawater on a coating of mucus and churns out domoic acid,
Pseudo-nitzschia blooms all along the West
Coast, especially around bays and estuaries fed by major
rivers. Unlike some other toxic blooms, which are often
called red tides, these aren't visible because their greenish-brown
coloring blends into the seawater.
Researchers studying Pseudo-nitzschia off
the mouth of the Mississippi River have unearthed evidence
in the seafloor that agricultural runoff from the nation's
heartland triggers the outbreaks.
Scrutinizing core samples from five locations
in the Gulf of Mexico, they found thick layers of microscopic
silica shells of Pseudo-nitzschia that coincided with a
deposit of nitrates and sediment that had flowed down the
The evidence is preserved in strata that
resemble a layer cake. It shows that Pseudo-nitzschia didn't
proliferate until the 1950s, when grain farmers began widespread
use of chemical fertilizers.
In contrast to the Mississippi Delta, such
telltale clues cannot be seen in marine sediments off the
Pacific coast because the seafloor is constantly being churned
As a result, West Coast scientists have
been looking for chemical signatures that would directly
link river discharges to the toxic blooms.
For the last three years, USC researchers
David A. Caron and Astrid Schnetzer have focused on a "hot
zone" of Pseudo-nitzschia spanning 155 square miles
of coastal waters off the mouths of the Los Angeles and
San Gabriel rivers.
The researchers are still looking for the
link. But one thing is clear, said Caron, a biological oceanographer:
"There is a big dose of nutrients."
Knowing about the effects of domoic acid,
scientists wonder whether algae blooms explain the freakish
behavior of coastal wildlife observed periodically over
Some speculate that Pseudo-nitzschia caused
the onslaught of crazed seabirds near Capitola, Calif.,
in 1961 that inspired Alfred Hitchcock's movie "The
Birds." Hitchcock, who was living in nearby Scotts
Valley, read a newspaper story about sooty shearwaters "wailing
and crying like babies," crashing into streetlights
and windows, nipping at people and vomiting up anchovies.
In 1998, sailors in Monterey Bay began
bumping into dark objects in the water. They thought they
were floating logs. They weren't. They were the bodies of
That year, more than 400 washed ashore,
dead or dying, victims of neurotoxic poisoning.
California's five marine mammal rehabilitation
centers were overwhelmed. Every year since, they have been
crowded with sea lions trembling with seizures.
This spring, the Marine Mammal Care Center
at Ft. MacArthur in San Pedro was often as busy as an inner-city
emergency room. Ailing sea lions were packed into chain-link
cages. Rescue workers kept bringing in new patients in pickup
trucks. The animals needed injections of anti-seizure medicine
or had to be hooked up to saline drips to flush the neurotoxin
from their systems.
On one typical day, listless sea lions
were flopped on their sides, flippers tucked in, too exhausted
to lift their heads. One was agitated, head weaving to and
fro, grunting and snorting. Another chewed obsessively on
All were females found comatose or acting
strangely on the beach. Many were pregnant and had seizures
just after giving birth.
"A California sea lion has as warm
and strong of a maternal instinct with a newborn as you
can see in any animal," said Robert DeLong, a government
ecologist who has studied sea lions in their Channel Islands
rookeries for 35 years.
Domoic acid can destroy that maternal bond.
Sea lions suffering from neurotoxic poisoning
usually show no interest in their young. Some that previously
cared for their pups shun them after suffering seizures
or even attack them when they try to suckle.
"I came in one day and pieces of the
pup were everywhere," said Jennifer Collins, a veterinarian
who worked at the Marine Mammal Care Center in San Pedro.
"We initially thought someone had broken in and macerated
one of the animals. Then we pieced it together and realized
that a mother had done it to her own pup."
Scientists first became aware of domoic
acid and its toxicity in 1987, when three people died and
at least 100 others were sickened after eating contaminated
mussels from Prince Edward Island in Canada. Nineteen people
were hospitalized with seizures, comas and unstable blood
Many of the patients never recovered gaps
in their memory, lending this malady a new name: amnesic
shellfish poisoning. An examination of brain tissue from
the three people who died showed severe loss of nerve cells,
mostly in the hippocampus, a part of the temporal lobe that
resembles a seahorse and plays a key role in memory and
Reported cases of the illness are rare
in North America because health authorities closely monitor
shellfish for toxins and because such seafood makes up a
tiny fraction of most people's diets. But for animals that
consume little else, domoic acid is a recurring danger.
The acid mimics a neurotransmitter, overstimulating
neurons that retain memory. The acid prompts nerve cells
to fire continuously until they swell and die.
During spring and summer, when Pseudo-nitzschia
blooms off the California coast, male sea lions don't eat.
They are too busy guarding their breeding territory on the
Channel Islands, where females mate soon after delivering
The females, in contrast, are ravenous
feeders while pregnant and while nursing. They gorge on
anchovies and sardines that have fed on toxic algae. Domoic
acid doesn't appear to affect the fish, but sea lions eat
anchovies in such quantities that they accumulate a toxic
Frances Gulland and other researchers have
been collecting miscarried sea lion fetuses and stillborn
pups on San Miguel Island. To their surprise, domoic acid
has turned up in the urine of these pups.
The neurotoxin is typically flushed from
an animal in about four hours. But Gulland found that domoic
acid can penetrate the placenta, bathing a developing fetus
in the neurotoxin for days.
California sea lions have a keen sense of direction. Although
their habitat ranges from British Columbia to Baja California,
they return to the same breeding beaches on the same islands
year after year.
But after attaching satellite transmitters
to the animals, Gulland and other researchers found that
many victims of domoic acid poisoning — even those
that appeared fully recovered — lost their way.
Some swam hundreds of miles out to sea
and were never seen again, bizarre behavior for creatures
that spend their lives in coastal waters.
Others washed up again on beaches, too
addled to make it on their own. One swam in tight circles
up the Salinas River.
Neuschwander was one of those who could
not find their bearings.
After spending a month at the Marine Mammal
Center near Sausalito last summer, the sea lion was eating
voraciously and seemed so vigorous that Gulland thought
she was ready to fend for herself again. She was released
back into the ocean in San Mateo County.
A week later, Neuschwander was found stranded
again. This time, she was more than 100 miles inland from
her natural home along the coast. She had traveled up rivers
and drainage canals and ended up on a hillside near Sacramento
She had an enormous gash running from her
chest to her back, possibly from a run-in with a barbed-wire
fence. She snapped at anyone who came close.
Back at the Marine Mammal Center, Neuschwander
wouldn't eat and began weaving her head again in endless
Gulland and her staff shaved a wide band
of fur off the sea lion's head, attached a dozen electrodes
and hooked them to an electroencephalogram to measure brain
activity. The needle jumped up and down, a sign that Neuschwander
was continuing to have seizures, though there were no visible
"The damage to the hippocampuses will
help trigger seizures, and further seizures will cause further
cell damage," Gulland said. "You get into this
whole vicious cycle."
So Neuschwander was driven across San Francisco
Bay and put into the MRI machine at Raytel Medical Imaging,
a clinic near UC San Francisco Medical Center. After the
magnets whirled, a computer screen displayed cross-section
images of her brain.
Dr. Jerome A. Barakos, a clinical professor
and director of neuro-imaging at the clinic, appeared in
his white coat. He was there to interpret the 250 images
that spooled out of the machine.
"The anatomy of a sea lion is not
too dissimilar to the human anatomy," Barakos said.
He confirmed Gulland's fear. On the right side of Neuschwander's
brain, the hippocampus was severely atrophied. It looked
less like a seahorse than like a withered tail.
Gulland paced around the lab, then pulled
aside one of her assistants, Michelle Caudle.
"So do we euthanize her? Do we take
her home and see how she does?" Gulland asked.
The two women shifted uncomfortably, arms
folded across their chests. They talked about how the animal
was losing weight and drifting in and out of delirium.
At 140 pounds, Neuschwander was 60 to 80
pounds lighter than a healthy adult female.
Caudle recalled how she wouldn't eat the
"happy fish," laced with sedatives, that sea lions
normally gulp down. Neuschwander shredded it, then spat
"She looks terrible," Gulland
said. "I didn't realize how thin she was. I mean, how
much do we make her go through?"
Gulland got a faraway look in her eyes.
Her face drooped.
"I'm OK with it," Caudle said.
"I am too. That's why we do it, right?"
To end the suffering.
Gulland blinked back tears. She took a
deep breath and rejoined the group to announce the decision.
The team took five vials of blood for future
studies. Then Gulland filled an enormous syringe with clear
pink liquid, pressed the plunger and shot 15 ccs of sodium
pentobarbitone, an overdose of the anesthetic, into a neck
Neuschwander let out one last, rasping
Gulland laid her hands on the sea lion's
body. The heart fluttered for a long two minutes.
Then it stopped.
Times staff writer Usha Lee McFarling contributed to