BIOACCUMULATION AND BIOMAGNIFICATION - Marine Pollution: What Everyone Needs to Know - page 159

toxin without apparent ill effects. The toxin can bioaccumulate
in other phytoplankton eaters, such as anchovies and sardines.
Domoic acid is a neurotoxin, causing short-term memory loss,
brain damage, and death in severe cases. It has been respon-
sible for several deaths and both permanent and transitory ill-
ness in over a hundred people. Amnesic shellfish poisoning
was first discovered in late 1987, when a serious outbreak of
food poisoning occurred in eastern Canada where a number
of patients died and others suffered long-term neurological
problems. Because the victims had memory loss, it was called
amnesic shellfish poisoning. However, since the toxin has
been found in finfish and the chemical structure of the toxin
is now known, a more accurate term is domoic acid poisoning.
It not only affects humans, but marine birds and mammals as
well. Marine mammal and seabird strandings and deaths off
the Southern California coast have been linked to this toxin.
Most of the animals found dead, including sea lions and har-
bor seals, tested positive for domoic acid.
What is Ciguatera?
The most widely reported HAB toxin disease is ciguatera,
which results not from eating shellfish but from consumption
of contaminated reef finfish. It is estimated that at least 50,000
people per year who live in or visit tropical and subtropi-
cal areas suffer from ciguatera worldwide. Patients suffer for
weeks to months with debilitating neurological symptoms. The
dinolagellate Gambierdiscus toxicus produces ciguatoxin (CGX)
and similar toxins. The dinoflagellates are eaten by herbivo-
rous fishes, which are then eaten by larger carnivorous fishes.
The toxins move up the food web and concentrate in the fish.
Larger individuals of species high up on the food chain in
tropical and subtropical waters, such as barracudas, snappers,
moray eels, groupers, triggerfishes, and amberjacks, are most
likely to cause ciguatera poisoning, although other species may
cause it. Ciguatoxin is odorless, tasteless, and heat-resistant, so