Abstract
Dinoflagellates from several locations along the Pacific coast were studied for the toxin composition and net toxicity. All toxic isolates obtained so far fall within the genus Protogonyaulax . The resting cysts of Protogonyaulax were found in the sediments from most locations sampled, from San Francisco to the Aleutian Islands. Their abundance varies widely. The toxicity per cell varies significantly with growth conditions, being several times higher under conditions that past studies have used for growth in the laboratory. Six new toxins have been isolated from the cultures, each of which can be converted to one of the 6 previously known toxins under mild conditions. This Conversion increases the toxicity by a factor that, depending on the toxin, ranges from 6X to over 70X.