Marine biotoxins, produced by phytoplankton usually during HAB
events, are some of the most potent toxins in the world and extremely
dangerous. For some toxins, doses at the microgram per kilogram
level are more than sufficient to kill. When enough toxin is accumulated
in fish or shellfish, small amounts of cooked or raw tissue can
kill a human. For example, recorded HAB events have produced enough
PSP toxin in mussels that the consumption of one or two small
mussels could have killed a normal, healthy adult human. While
some toxins are very potent, i.e., requiring only small amounts
to produce illness or death, other less potent toxins may accumulate
to such high levels that they still can cause harm. For example,
the total dose of domoic acid to produce a minimal toxic effect
is fairly high (i.e., tens of milligrams) but it can accumulate
in sufficient quantities in shellfish to produce deadly results
(ranging from mild stomach distress to permanent brain damage
and even death).
The risk of poisoning from consumption of fish or shellfish is
serious and of concern to public health authorities in all coastal
environments. This is true both in the United States and worldwide.
The risk and threat to public health is so great that virtually
all countries have instituted some form of risk management plan
to deal with marine biotoxins. These "sanitation" plans are difficult
to design and implement because the properties of the toxins are
only poorly understood, not to mention the origins and responsible
alga may also not be known.
NOAA's region of responsibility in the Pacific encompasses an
area that stretches literally from the
North Pole to south of the equator. Within this region a myriad
of toxins occur that range from temperate toxins, such as Paralytic
Shellfish Poison or PSP (the syndrome is caused by suite of toxins
called the saxitoxins or gonyautoxins) and domoic acid poisoning,
to tropical toxins such as ciguatera fish poisoning (the toxin
is called ciguatoxin). The properties of these toxins are also
quite different, ranging from the "fat soluble" ciguatoxin to
the water soluble toxins of domoic acid and PSP.
While these toxins originate from phytoplankton, these algae
come from ecological niches that are all very different from each
other. In the tropics, ciguatera poisoning is caused essentially
by reef dwelling fish and the responsible phytoplankton is a dinoflagellate
(Gambierdiscus toxicus) that lives on coral reefs and
other surfaces. In temperate waters, the PSP toxins are produced
by the dinoflagellate Alexandrium catenella and domoic acid by
diatoms in the genus Pseudo-nitzschia. All of these differences
(chemical, ecological, and biological) make it difficult to design
simple, one stop monitoring techniques for these toxins and poisoning
syndromes that would be applicable throughout the region.
To read more about marine biotoxins and methods of detection
and analyses, please use the navigation bar to the right.
For more in depth descriptions of the toxin syndromes, we
suggest that you might want to look at the extensive monograph
by Bruce W. Halstead ("Poisonous and Venomous Marine Animals of
the World" (Darwin Press). .