Published Date: 2003-06-04 23:50:00
Subject: PRO/AH> Dolphin, sea lion die-off, domoic acid - USA (CA)
Archive Number: 20030604.1363
DOLPHIN, SEA LION DIE-OFF, DOMOIC ACID - USA (CA)
ProMED-mail, a program of the
International Society for Infectious Diseases
Date: 3 June 2003
From: A-Lan Banks <A-Lan.Banks@derwent.co.uk>
Source: Environmental News Network, California [edited]
A naturally occurring but deadly toxin produced by sea algae is
killing record numbers of dolphins and sea lions along sections of
California's southern coast, the state's wildlife agency said
recently. The animals are being poisoned by domoic acid, a nerve
toxin produced by a certain species of microscopic algae, said the
California Department of Fish and Game.
The exact cause is a mystery, but scientists speculate that the algae
may be thriving on nutrients from agricultural runoff or sewage, said
Chamois Anderson, a spokeswoman for the department. Weather patterns
could also play a role.
Since April 2003, 5 dolphins and 148 California sea lions have been
found stranded on beaches from Santa Barbara County south through
Orange County. All of the dolphins died, and many of the sea lions,
most of them large adult pregnant females, are being treated at
marine mammal rehabilitation centers. Pelicans have also been taken
to shelters for care, the state agency said.
Marine animals and seabirds can be poisoned by eating small fish that
have ingested the toxin. Filter-feeding animals like mussels and
small fish like sardines feed on the toxin-laced algae.
Last year, according to the California wildlife agency, more than
1000 marine mammals were found stranded or dead on state beaches.
Hundreds of seabirds, including endangered brown pelicans, grebes,
and loons, were also affected by that outbreak.
Domoic acid can cause human illness or even death, and the California
Department of Health Services warns each year not to eat
self-harvested mussels or shellfish between 1 May and 31 Oct.
The health agency also advises Californians to eat only the white
meat of sport-harvested, bivalve clams or scallops and said elevated
levels of domoic acid have been detected in mussels, oysters,
sardines, and anchovies from Santa Barbara, Ventura, Los Angeles, and
Orange Counties. So far, there have been no reported cases of human
poisoning from domoic acid in the state.
Officials said people should not try to help beached animals or
birds, because domoic acid poisoning can provoke aggressive behavior
and the animals are too sick to go back in the water.
[An excellent review of domoic acid in mammals can be found in
"Mammal, bird die-off, domoic acid - USA (CA) (02) 20020708.4702."-