Growth and Toxicity of a Marine Dinoflagellate, Gonyaulax tamarensis

Gonyaulax tamarensis, the dinoflagellate species associated with paralytic shellfish toxicity on the Atlantic coast of Canada, was isolated in unialgal culture and studied for its growth and toxigenic characteristics. Although low salinity and high temperature promoted growth in cultures, salinity appears to be a more important ecological factor than temperature in controlling the summer abundance of this dinoflagellate in nature.Toxin yield in unialgal cultures is largely a function of cell density. The toxic principle synthesized by G. tamarensis, for most part, remains within the cell and can be recovered in substantial amounts by lysis of the cells. Comparison with other species indicates that G. tamarensis is potentially the most toxic of the known toxic species of Gonyaulax. Bacteria play no direct role in toxin production, but may influence toxigenesis indirectly by promoting growth of dinoflagellates.