This Sea Grant project focused on domoic acid production by the toxin-producing diatoms (Pseudo-nitzschia australis and P. multisieries) in coastal California waters. There were two major aspects of our work: 1) the development of a laboratory HPLC assay for measuring domoic acid and the tracking of DA in a field mortality event using the HPLC assay, and 2) developing continuous culture facilities and examining the nutrient physiology of Pseudo-nitzschia species.