Contents
Robofly
Killer Surf!
Tracking the
Bloom
This Won’t Hurt a
Bit
Echoes from the
Past
A Ride on the Wild
Side
Tongue Twister
KC and the Ground Sludge
Band
Twinkle, Twinkle Collapsing
Star
One if by Land, One if by
Sea
SciSSIllustrated
Article
SciSHome
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Tracking the
Bloom
When
sea lions started dying in Monterey Bay, scientists raced
to discover the cause.
By: Liese Greensfelder
A
n
hour before midnight on Saturday of Memorial Day weekend,
1998, Chris Scholin and his wife, Edie Rue, were docking
their sailboat in Monterey harbor at the south end of
Monterey Bay when they spotted something odd. A man was
herding a young sea lion down the launch ramp with a large
board, trying to force it into the water.
S
cholin
came to work at the institute in 1992, the year after
hundreds of brown pelicans and cormorants had staggered
around and died on local piers and beaches. The animals had
been poisoned after feasting on fish that had just fed on
masses of a toxic microalga called Pseudo-nitzschia
australis. Although this organism had long been known to
exist in normally innocuous numbers in local waters,
something had caused its population to explode—a
phenomenon known as a marine bloom. The incident left
scientists and public health officials worried. It was the
first documented case of wildlife poisoning on the West
Coast of North America attributed to
Pseudo-nitzschia. In fact, only once before had any
Pseudo-nitzschia species been implicated as the cause
of widespread poisoning, but with devastating results. In
1987, three people died in Canada’s eastern province of
Prince Edward Island after eating mussels loaded with domoic
acid, the potent toxin produced by the microalga. Another
107 people fell seriously ill after eating the mussels. Ten
survivors remained permanently disabled with total loss of
short-term memory. Domoic acid, a neurotoxin, had created
lesions in the hippocampal region of their
brains.
S
cholin
set to work as soon as he arrived at the institute to
develop a method to warn of potentially devastating marine
blooms. In a few years of driven research, he devised an
ingenious system that could rapidly detect and identify 12
separate species of toxic microalgae based on their genetic
makeup. Now Scholin realized he might be one of the few
people who understood the significance of the ailing sea
lions. With the phone calls he had made, he joined a
growing team of scientists who would work together through
the coming weeks and months to probe the cause and
consequences of a rare epidemic that had swept through
Monterey Bay.
B
y
the time Scholin and Rue set off for their Saturday sail, he
had been drawing seawater samples from various locations
around the bay for nearly three years, analyzing them for
telltale rises in populations of microalgae using the
detection system he had devised. Just two weeks earlier, he
had noticed a small increase in his normal background
readings of Pseudo-nitzschia australis. Each ensuing
sample had produced a higher reading. He’d called various
agencies to report the worrisome finding. “We were calling
just about anybody we could think of, telling them there was
an algal bloom going on,” he said. But blooms had never
been predicted before, and officials were virtually
unfamiliar with Pseudo-nitzschia. “They would just
say, ‘Domoic what?’“ Scholin recounted. With no
previous experience in monitoring a bloom, Scholin himself
did not know how to interpret the significance of his
findings.
B
uton
Saturday, Scholin and Rue had noticed oily brown patches
dotting the bay. “It smelled like fresh-cut grass,” Rue
said, “or like a salad that got put through a blender.”
S
omething
else was not right that day. “It was like a smorgasbord for
fish. They were feeding like crazy,” Rue said. When she
thinks back on it, she believes the fish they saw were
anchovies, probably in a frenzy of feeding on a dense bloom
of Pseudo-nitzschia. But not until she and Scholin
saw the dazed sea lion on the launch ramp did the jumbled
pieces of the puzzle suddenly fit together.
W
hile
Scholin stood at the pay phone doing his best to raise an
alarm, another scene was unfolding just a few miles north.
Overwhelmed staff and volunteers at the Marine Mammal Center
in Moss Landing were working 24-hour shifts trying to save
the lives of dozens of desperately ill California sea lions.
Some of the sea lions were having seizures, others were
semi-comatose. Many were foaming at the mouth and weaving
their heads in random circles, like the young animal Scholin
and Rue saw on the launch ramp. Because they didn’t know
the cause of the sea lions’ illness, the only thing workers
could do was treat visible symptoms—giving Valium
injections to control seizures, and injecting fluids under
the skins of the animals to counter dehydration caused by
fits of diarrhea and vomiting.
A
nonprofit organization, the Marine Mammal Center has rescued
more than 5,000 injured, ill, or stranded marine mammals in
its 25-year history. Sick and injured animals found in the
Monterey Bay area are taken first to the center’s Moss
Landing facility, where they are stabilized before being
trucked to the main treatment center in Sausalito, five
miles north of San Francisco.
“W
e
were trying to make contact with any labs we could on
Saturday, Sunday, and Monday. But it was a holiday weekend,
and no one answered their phones,” said Frances Gulland,
director of veterinary services for the center in Sausalito.
Gulland, a veterinarian and epidemiologist, suspected at
first that the sea lions could be suffering from a highly
potent virus, like the one that killed more than 18,000
harbor seals in the North Sea between England and Denmark in
the late 1980s. Though the logistics of keeping all the
animals separated at the crowded facility in Sausalito were
staggering, Gulland knew it was imperative to keep the sea
lions quarantined. Without knowing whether they suffered
from a contagious disease, she dared not risk them coming
into contact with the 150 harbor seals, elephant seals, and
sea lions already being treated at the Center. Most of these
animals were underweight victims of the brutal storms that
wracked California’s coast through the long El Niño
winter of 1997-98.
T
hrough
the weekend, volunteers at Moss Landing were working all
three of the center’s phones almost continuously, responding
to people calling in reports of ill animals along a 100-mile
stretch of coast. Other volunteers were sent out to find
sea lions and load them into trucks. “Normally, you put a
net on them and use boards to maneuver them into a carrier,”
said Shelbi Stoudt, the center’s stranding coordinator at
Moss Landing. “These animals were virtually comatose.
Their eyes were open, but they weren’t really conscious. We
disregarded the typical rescue equipment and basically
physically lifted these animals into carriers. What we
remember is our pure exhaustion.”
B
y
the end of the weekend, the center’s pickup proved
inadequate for the growing load. “Literally, our trucks were
moving nonstop, going from one beach to the next, loading
animals, bringing them in and unloading them,” Stoudt said.
Finally, she rented a U-Haul truck and sent 18 sea lions,
each weighing about 225 pounds, to Sausalito.
C
oastal
dwellers have observed marine or “algal” blooms for
centuries. These phenomena occur when populations of
microalgae a component of the ocean’s microscopic
plankton community—explode in response to just the right
amount of sunshine and nutrients in the sea. Algae with a
normal population of 1,000 individuals per liter of seawater
can quickly reach concentrations of 60 million per liter
during a bloom. In such huge numbers, the tiny algae impart
different colors to the water. Some species turn water red,
giving rise to the popular term “red tides.” But this is a
misnomer, for blooms can be brown, green, yellow, or even
colorless, and they are not influenced by tides.
A
lgal
blooms occur more frequently in the shallow, warmer waters
along the coast than in the deep sea. Some blooms complete
their growth cycle then disappear quietly, leaving no trace
of their presence. But some blooms can severely damage the
marine environment, killing other creatures when the blooms’
vast masses deplete the water of oxygen or by simply shading
out other life dependent on clear water and sunlight.
Numerous algal species produce potent toxins that can work
their way up the food chain from shellfish and smaller fish
to large fish, birds, and mammals, including humans. Most
of these toxins act upon the nervous system of mammals, and
many are so powerful that humans can be affected just by
inhaling them in a sea-borne mist.
D
uring
the past two decades, the frequency of algal blooms has
increased in almost all coastal areas of the world.
Scientists suspect a variety of causes, including the
worldwide destruction of wetlands that normally serve as a
natural filter for storm runoff. Sediment that used to
lodge in the wetlands now flows straight to sea where it
provides plankton with an overabundance of mineral
nutrition. Numerous species of harmful algae have expanded
their range in recent years, many hitchhiking into new
territory in the ballast water of ships. Shifts in ocean
currents and nutrient cycling as a result of global warming
may also contribute to increased frequency of blooms. Many
pollutants, such as industrial waste, inadequately treated
wastewater, and agricultural run-off contaminated by
pesticides and fertilizers, find their way directly into the
sea, where they alter the natural balance of marine life,
causing erratic population explosions of certain
microalgae.
D
etecting
an algal bloom or tracking a poisoning incident back to a
particular species is always difficult and sometimes
impossible. Even using microscopes, scientists cannot
identify many species in the field. Diatoms, the algal
subgroup that includes Pseudo-nitzschia, present
scientists with a notoriously challenging identification
problem. Normal microscopes don’t have the magnification
power required to reveal the intricate geometric patterns of
the diatoms’ shell-like bodies, the only visible
distinguishing characteristics of many species. Only by
viewing diatoms with a scanning electron microscope, a
time-consuming and expensive process, can scientists make a
positive identification.
B
ut
identification is only the first step in tracking a bloom.
Water taken from Monterey Bay at any time will reveal large
numbers of several Pseudo-nitzschia species. To
determine whether populations are high enough to cause a
problem, the algae must be counted, one by one, a process
described by one scientist as “a hideous and evil thing made
even more difficult by trying to pick out one specific kind
in the midst of a hodgepodge.”
S
ometimes
the only physical evidence of a toxic bloom may be a group
of convulsing pelicans or seals, or desperately ill people.
Public health officials must consider every possible factor
when confronted with an epidemic: injury, pollution, and
disease are other possible causes. Even the toxin itself
may have disappeared from the animal’s system, leaving only
its grim symptoms. It took researchers years to discover the
cause of the two documented Pseudo-nitzschia
epidemics.
“I
t’s
like searching for disease organisms where there are
zillions of things that might be responsible for an
infection,” Scholin said. “And you want to know as quickly
as possible which thing it is so you can treat it
appropriately.” Scholin wanted to arm public health
officials with an early warning system for toxic blooms.
His vision was to develop a field kit for monitoring
seawater samples that relied on easy-to-read chemical
reactions, something like the color changes of litmus paper
or the pattern of a home pregnancy test kit.
T
he
biologist knew that a good model for his task already
existed in biotechnology and medicine. Scientists in those
fields have developed molecular “probes,”
designer-engineered molecules that hunt ("probe") for a
specific molecular construction unique to the organism the
scientists wish to identify. Usually this is a sequence of
DNA or its single-stranded cousin, RNA. The probe not only
finds and chemically latches itself to the sequence, but
also produces a detectable signal once it has attached
itself to its target.
B
efore
coming to the Monterey Bay Aquarium Research Institute,
Scholin studied the molecular biology of toxic microalgae at
Woods Hole Oceanographic Institute in Massachusetts. That
work gave him a running start at the institute, where his
first task was to determine which microalgae species in
Monterey Bay presented the greatest threat. Eventually, he
chose 12 species. His first years of work were devoted to
mapping or “sequencing” the molecular structure of the RNA
of these organisms. Upon completing this job, he compared
all the maps, selecting from each a short segment of RNA
that was unique to the species. Then he set to work
developing a series of molecular probes, one for each
selected segment.
S
cholin
designed two probes for the RNA sequence he chose from
Pseudo-nitzschia australis. The first he bound to a
fluorescent compound. When the probe latched onto the RNA
inside an intact Pseudo-nitzschia, the tiny organism
glowed a fluorescent green. But these glowing cells could
only be seen and counted through a microscope, a cumbersome
procedure in the field. The second probe acted on a solution
of chemically macerated Pseudo-nitzschia. Scholin
designed this probe to turn blue when it captured the
targeted RNA. The higher the concentration of
Pseudo-nitzschia in the water sample, the bluer the
solution. A person in the field could rapidly estimate the
concentration of the microalgae in the water by mixing
seawater with this probe and comparing the resulting color
to a chart prepared by Scholin.
B
y
1995, Scholin had taken his work out of the laboratory and
into the field. Once or twice a week he and his students
used the probes to analyze water samples they collected from
Monterey Bay. On May 11, 1998, he noticed a rise in the
count of Pseudo-nitzschia australis. The population
of the microalgae peaked ten days later, the day before
Memorial Day weekend.
W
hen
they returned to work on Tuesday following the three-day
weekend, scientists from around the country started to
return the calls placed to them by Frances Gulland. A
biologist with the California Department of Fish and Game
told the veterinarian about the message Scholin had left on
his telephone answering machine on Saturday night.
Intrigued that someone from the Monterey Bay Aquarium
Research Institute was suggesting a cause of the epidemic,
Gulland immediately called Scholin. They spoke only
briefly, but Scholin’s information about his discovery of
rising Pseudo-nitzschia counts was the key piece of
evidence Gulland needed.
“T
he
great thing was when I finally made contact with him, here
was a man who knew that it was a plankton,” Gulland said.
“Once I’d talked with Chris (Scholin), I could convince the
labs to run assays for domoic acid.” With so many other
possibilities to consider until now, no lab was willing to
run the expensive assay for domoic acid, a toxin that had
never before been detected in a marine mammal.
W
ithin
days of Scholin’s call, both the National Marine Fisheries
Services laboratory in Seattle and the National Ocean
Services laboratory in Charleston, South Carolina, confirmed
the presence of domoic acid in the samples sent to them
earlier by Gulland.
A
t
last the fatigued rescue workers had a grasp on the nature
of their invisible foe.
“W
hen
we found out that it was most likely domoic acid, there was
a change of confidence,” Shelbi Stoudt said about her
volunteers at the center’s Moss Landing facility. “Then we
knew that what we were doing actually was good.” By
treating the animals’ visible symptoms with Valium and
forced rehydration, workers had done the best thing
possible. Domoic acid is soluble in water, so every time the
sea lions urinated, they rid themselves of some toxin. In
Sausalito, a relieved Gulland could stop worrying that the
animals were suffering from an infectious disease. Her
staff no longer needed to work under laborious quarantine
measures in the overcrowded treatment center.
T
he
tiny organism responsible for the mass poisoning,
Pseudo-nitzschia australis, is no newcomer to the
West Coast. Identified in the 1930s, it is a dominant
species of plankton up and down the coast of California.
But until last year, its effects on people and wildlife had
been documented only twice: the 1987 poisoning in eastern
Canada and the 1991 pelican incident in Monterey Bay.
“There actually have probably been tons of
Pseudo-nitzschia blooms,” says Mary Silver, a marine
biologist at the University of California, Santa Cruz. “But
our awareness of them depends on a whole lot of events
coming together.”
T
he
first step is for the bloom to occur when anchovies, a
migratory fish, are abundant in local waters, Silver says.
Pseudo-nitzschia are so small that most fish ignore
them. But anchovies have special gills that filter algae
from water. During a bloom, anchovies gorge themselves on
the tiny plankton.
T
he
next step, says Silver, happens only when anchovy-eating
predators are present. “Especially [predators] that
humans are interested in,” she says. “If we had beach crabs
dying in huge numbers, no one would know or care. But
anchovies feed a lot of animals and birds that we care a lot
about.” The five-inch-long silvery fish is a favorite food
for seals, sea lions, pelicans, and many other animals.
N
ext,
Silver says, a beach is necessary, so that sick and dying
predators come ashore someplace where people notice them.
Where the coastline is rocky, ailing and dead animals remain
in the water, unnoticed by humans.
S
ilver
tells the story of a 1961 incident in Santa Cruz when
hundreds of deranged shearwaters, ocean-going birds that
feed on anchovies, flew into the city, crashing into
buildings and cars. According to local lore, Alfred
Hitchcock, who lived in nearby Scotts Valley, called the
newspaper and grilled the reporter who covered the story to
find out all he could about the event. A year and a half
later, The Birds, Hitchcock’s classic thriller about
a coastal town terrorized by deranged seabirds, hit theaters
across the country. Silver says the shearwater incident had
all the earmarks of classic domoic acid poisoning.
S
oon
after Scholin and Gulland realized that Monterey Bay was in
the throes of a toxic bloom, Silver was in Monterey looking
for anchovies. The fish are not a sports fish and not
commonly caught or sold from the pier. An amateur fisherman
happened to hear that she’d been asking for the fish. He’d
caught some the day before and had them in his
truck.
T
he
fish were on ice, maybe 12 hours old, and Silver took them
straightaway to Chris Scholin’s laboratory. There she found
Peter Miller and Roman Marin, two graduate students who
worked with her and Scholin. Silver and the students
immediately cut the fish open. When Silver turned the brown
contents from one fish gut under the microscope she
instantly recognized hundreds of slender, spindle-shaped
forms of Pseudo-nitzschia. But the light microscope
could not tell her which of the many similar species she was
looking at. Marin, meanwhile, was testing the contents of
another gut with the molecular probe. Within minutes, the
blue results told the researchers that they were looking at
the deadly Pseudo-nitzschia australis. The next day,
Miller confirmed the assay by checking the sample under the
scanning electron microscope, the gold standard test for
identifying the diatoms.
A
s
the evidence accumulated that the sea lions were indeed
suffering from domoic acid poisoning, scientists from state
and federal agencies flocked to Monterey Bay to glean all
the information they could from the outbreak. They tracked
the bloom for several months and found that it had probably
originated at least 100 miles to the south, then continued
to move slowly northward. By late July, researchers were
finding razor clams contaminated with domoic acid along the
coast of Washington. In September, levels had risen so high
that authorities banned harvest of the clams.
S
cientists
are now analyzing the data they collected, hoping to explain
the many unanswered questions surrounding the bloom. What
caused the phenomenon? Why did it move north along the
coast? Why were so few sea lions affected at a time when
thousands were in Monterey Bay?
C
hris
Scholin is continuing to develop probes for even more
microalgal species. He is also working with colleagues to
design and construct automated monitoring stations that
incorporate the probes. Attached to buoys, the stations
would send microalgal counts and other data to computers on
land, relieving scientists and officials who track marine
blooms of the tedious chore of collecting water samples
along hundreds of miles of coastline.
B
y
the time the Pseudo-nitzschia bloom in Monterey Bay
ended in June, more than 50 of the sea lions treated at the
Marine Mammal Center in Sausalito had died, another 29
survived, but needed extended care, and 19 appeared fully
recovered. No reports surfaced of any human illness due to
the bloom. Humpback whales feeding in the bay at the time
also seemed unaffected. But domoic acid was found in
samples taken from three ill sea otters. Two of the otters
died and one remained permanently impaired, apparently with
severe memory loss. The creature was so easily distracted
it would seem to forget the food it held between its
paws.
B
y
late fall the Marine Mammal Center in Sausalito had released
all but three of the surviving sea lions back to sea. On
November 6, the center’s biologist, Michelle Lander, loaded
the three survivors into dog kennels in the back of a truck
and drove to Point Lobos State Reserve, three hours away at
the southern tip of Monterey Bay. There, Lander backed the
truck as close as possible to the rocky shore of Weston
Beach. With the help of colleagues, she carried the kennels
to the water’s edge, where she opened the doors and guided
the sea lions back to the ocean.
F
or
two months Lander received signals from radio transmitters
she’d glued between each animal’s shoulder blades. The last
transmissions she received before the instruments fell away
told her that one of the animals still swam the waters of
Point Lobos. The other two had made their way 50 miles
north where they frolicked with hundreds of companions at
Año Nuevo Point, a favorite haunt of California sea
lions.
-
- BIO
-
- WRITER
Liese Greensfelder
- certificate,
agricultural sciences, Langvin School of Agriculture, Norway;
B.S., plant science, agronomy, University of California, Davis;
M.S., horticulture, pomology, U.C. Davis.
Internship: freelancing.
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1999 Liese Greensfelder
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