California HAB Bulletin: May – June 2018

The probability of a Pseudo-nitzschia bloom for the month of May was high all along the coast. Probabilities were low in most of the Southern California Bight once you move south of the Santa Barbara Channel, with high but most likely spurious probabilities of a Pseudo-nitzschia bloom in the very nearshore where C-HARM is known to be less accurate. The only location where the Harmful Algal Bloom Monitoring and Alert Program (HABMAP) pier sampling by SCCOOS and CeNCOOS showed high potential for a toxigenic Pseudo-nitzschia (seriata size class) bloom was at the Cal Poly Pier in early May.

C-HARM predicted the highest likelihood of domoic acid production in the Southern CA Bight, the offshore region of central CA, and in the nearshore zone of the North Coast. The CA Dept. of Public Health has issued a sport-harvested razor clam advisory for the North Coast (Del Norte and Humboldt Counties). Marine mammal stranding data from The Marine Mammal Center in central CA posted that most strandings were due to malnutrition and illness rather than domoic acid toxicity in May, just as they were in the month of April. This suggests that domoic acid is either not high in the central CA offshore ecosystem (in contrast to C-HARM predictions) OR that there is a delay in domoic acid toxicosis cases arriving at TMMC. This situation is TBD.  Interestingly, the CA Dept. of Public Health just lifted advisories on sport-harvested whole scallops and clams in Ventura and Marin Counties where shellfish were previously at high risk of spreading Paralytic Shellfish Poisoning. These advisories are still in effect in Santa Barbara, Santa Cruz, and Sonoma Counties!

Mean Probability of Pseudo-nitzschia Bloom for May 2018

Mean Probability of a Domoic Acid Event for May 2018