HARMFUL ALGAL BLOOMS AND RED TIDE PROBLEMS ON THE US WEST-COAST

On the U.S. west coast, the main toxin-producing algal species are din oflagellates in the genus Alexandrium that cause paralytic shellfish p oisoning (PSP) and diatoms in the genus Pseudo-nitzschia that produce domoic acid and cause domoic acid poisoning (DAP). Other harmful speci es, including the raphidophyte Heterosigma nkashiwo and the diatoms Ch aetoceros convolutus and Chaetoceros concavicornis, kill fish at aquac ulture sites, but are not harmful to humans. Water discolorations (red tides) caused by nontoxic dinoflagellates also occur throughout the a rea. Early records, partially based on local native lore, suggest that algal toxins have been present along this coast for hundreds of years , but actual scientific information is sparse. We review what is now k nown about harmful algal blooms in this vast area, including the hydro graphic regimes that induce and(or) support blooms, bloom dynamics, an d the biology of the causative species.