Subject: PRO/AH> Mammal, bird die-off, domoic acid - CALIFORNIA
MAMMAL, BIRD DIE-OFF, DOMOIC ACID - USA (CA)
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A ProMED-mail post
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ProMED-mail, a program of the
International Society for Infectious Diseases
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Date: Weds 22 May 2002 4:36 AM EDT
From: ProMED-mail <promed@promedmail.org
Source: AP Online [edited]
Algae deadly for Californian marine mammals
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Birds falling from the sky. Pelicans having seizures. Dolphins dying on
beaches. For 2 months, a growing number of marine mammals and birds have
been dying along the California coast. About 70 dolphins have washed up on
state beaches, while more than 200 sea lions and 200 seabirds have become
sick or died.
One of the leading suspects is domoic acid, a potent toxin attacking the
brain. The naturally occurring toxin is produced by the plankton [genus]
Pseudonitzschia. The toxin moves up the food chain from the slender,
glass-shelled diatoms to sardines, anchovies, crabs, and other shellfish
that in turn become dinner for birds and marine mammals.
"There's dead pelicans on the beach, and then these weird ones having
seizures," said Jay Holcomb, director of the International Bird Rescue
Research Center. "We had the public calling in, saying, 'These birds are
falling out of the sky'."
Blooms of Pseudonitzschia have occurred before but experts say it was only
recently that sealife deaths were linked to them. Scientists warn that
other types of microscopic sea life also can produce toxins.
This month record high levels of domoic acid, up to 380 parts per million
(ppm), have been found in mussels taken from Santa Barbara waters. The
federal alert level is 20 ppm, said Gregg Langlois, a marine biologist with
the state's Department of Health Services. Some researchers believe domoic
acid poisoning caused an incident in 1961 that partly inspired Alfred
Hitchcock's film "The Birds". Seabirds that may have eaten tainted
anchovies descended on villages in the Santa Cruz area, nipping people,
staggering around, smashing windows, and smacking into cars and houses.
No human illnesses have been reported in California but state health
officials advise against eating locally sport-harvested shellfish, crabs,
sardines, and anchovies. Commercially harvested seafood is considered safe
because it is inspected.
Humans eating tainted seafood can get amnesic shellfish poisoning, which
can cause twitching, nausea, permanent short term memory loss, and even
death. High domoic acid levels prompted a partial shutdown of mussel
harvesting along Prince Edward Island in Canada last month. The link
between the acid and human illness was discovered there in 1987 after more
than 100 islanders became ill and several died from eating tainted mussels.
In 1991 the crab season in Washington, Oregon and California was halted
after tests detected domoic acid in crab meat. The deaths of more than 400
California sea lions in 1998 also were traced to the acid. But research
into the plankton is so recent that nobody is sure what sparks the algae
growth or why the cells produce different levels of the toxin at different
times. California's long coastline means many more animals might have
perished out of sight of the public. Also, the deaths could have a larger
impact by whittling down isolated breeding colonies and by killing off
mothers during breeding season.
By some estimates, harmful algal blooms have caused more than $1 billion in
losses in the United States in the past several decades, including loss of
tourism, fisheries and the costs of treating public illnesses, according to
the National Oceanic and Atmospheric Administration. Some bacteria and
viruses attack certain algae species but more research is needed before a
biological remedy might be available. Even then, the impact on the
environment would be uncertain.
"It's a complex biological system and I don't think we have any idea of
what will happen if you begin to perturb it," said Christopher Scholin,
staff scientist with the Monterey Bay Aquarium Research Institute. "You
might get something worse." The latest outbreak began in March in northern
California. The high levels found in Santa Cruz and Monterey Bay subsided
and the problem now is concentrated in the south, Langlois said.
The Marine Mammal Care Center in San Pedro has treated about 170 sea lions.
"They come in exhibiting seizures. Some are comatose. They're disoriented,
lethargic," director Jackie Jaakola said.
Further information on the internet:
Marine Mammal Care Center: <http://www.mar3ine.org/mmcc/>
Algal bloom information: <http://www.redtide.whoi.edu/hab/>
NOAA: <http://state-of-coast.noaa.gov/bulletins/html/hab-14/hab.html>
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ProMED-mail
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[Domoic acid is a neurotoxic tricarboxylic amino acid structurally related
to kainic and glutamic acids. It was chemically identified after its
isolation in 1958 from the seaweed Chondria armata, found off the coast
of Japan. In 1987, more than 100 people became ill, and several people
died, following the consumption of blue mussels caught off Prince Edward
Island, Canada. Canadian scientists found that domoic acid had entered the
food chain when the mussels fed on a toxic algal bloom of the pennate
diatom Pseudonitzschia pungens forma multiseries. - Mod.TG]