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 dinoflagellates in the genus Alexandrium that cause paralytic shellfish poisoning (PSP) and diatoms in the genus Pseudo-nitzschia that produce domoic acid and cause domoic acid poisoning (DAP). Other harmful species, including the raphidophyte Heterosigma nkashiwo and the diatoms Chaetoceros convolutus and Chaetoceros concavicornis, kill fish at aquaculture sites, but are not harmful to humans. Water discolorations (red tides) caused by nontoxic dinoflagellates also occur throughout the area. 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 known about harmful algal blooms in this vast area, including the hydrographic regimes that induce and(or) support blooms, bloom dynamics, and the biology of the causative species.