Be sure to also read the special Red Tide Bulletin: Spring 2020 

Pseudo-nitzschia - C-HARM tells us where conditions are suitable for species of the diatom Pseudo-nitzschia spp. (all size classes) to grow well and where they might be more likely to produce domoic acid (DA). The predicted suitable habitat for Pseudo-nitzschia spp. was spread throughout coastal California from the Santa Barbara Channel to the Oregon border in August, a pattern in the C-HARM model that has persisted but with some nuances each month. This indicates that C-HARM is predicting positive habitat suitability for Pseudo-nitzschia in most parts of coastal California, something that is corroborated by the frequent presence of Pseudo-nitzschia species at our pier sites, albeit not always at bloom levels. In general, the central and north coasts and the Santa Barbara Channel exhibited persistently high bloom probabilities. Local minima in Pseudo-nitzschia bloom probabilities occurred in the 20-50 km nearest the coastline throughout the state at various times in the month. Bloom probabilities in the Southern California Bight trended high throughout the month, although confined more to the nearshore zone and with high spatial and temporal variability, similar to the previous month. While COVID-19 sampling restrictions continue to hamper our ability to acquire HABMAP observations from piers, we do know that the abundance of the toxigenic Pseudo-nitzschia "seriata" size class remained at zero at Santa Cruz Wharf throughout August. This is both consistent and inconsistent with the C-HARM bloom probabilities at the pixel near the SC Wharf since they were highly variable, bouncing between zero and 100% probability for bloom levels of Pseudo-nitzschia spp. At Cal Poly Pier, the observed abundance of the less toxigenic Pseudo-nitzschia "delicatissima" size class well exceeded bloom levels at the end of July and again at the end of August, corresponding with very high bloom probabilities close to shore in the SLO region in August that was predicted to be more persistent than pier sampling would indicate. The only southern California sites where we have observations available for all of August are Stearns Wharf in Santa Barbara and Santa Monica Pier. The toxigenic group Pseudo-nitzschia 'seriata' exceeded the bloom threshold at the end of August, while neither size class reached bloom levels at Santa Monica Pier in August. The highest abundances of the Pseudo-nitzschia "seriata" size class recorded by the CDPH were located near San Francisco.

Moderate to very high probabilities (60-100%) of particulate DA (pDA) were predicted for most of the California coast throughout August, maintaining the large offshore extent predicted in July. South of the Santa Barbara Channel, pDA was often predicted to exceed the 500 ng/L threshold but with a patchy distribution throughout the Bight, and as with Pseudo-nitzschia predictions, but those high probabilities extended far offshore as compared to those in July.  Probabilities for pDA along the central coast from Carmel to San Luis Obispo County exhibited local minima in the nearshore, sometimes dipping into zero probability of high pDA in the SLO region. The Los Angeles region/San Pedro Basin was a relative hot spot experiencing persistently high pDA probabilities throughout August, as in July. While much of the elevated pDA probabilities extended very far offshore, predicted cellular DA (cDA) risk appeared to be contained in a fairly tight nearshore band for much of the coastline and was consistently high from northern San Luis Obispo County to the Oregon border for the first half of the month, with local minima and a lot of variability from Sonoma County to the Mexican border. The overall take-away is that cDA was persistently high in the North Coast, suggesting a possible issue there. The consistently high probabilities for pDA along the central coast and parts of LA in the Bight are consistent with the three California Sea Lion strandings from suspected DA toxicosis reported by The Marine Mammal Center (TMMC) from San Mateo to SLO Counties in August, and the one California sea lion stranded in the LA area from suspected DA toxicosis at the beginning of August as reported by the Marine Mammal Care Center of Los Angeles (joining the one LA stranding at the end of July). This is consistent with the C-HARM predictions of high pDA and high cDA in those regions. There are no available domoic acid measurements from HABMAP yet available for August.

Alexandrium -  CDPH recorded low or zero Alexandrium spp. at all sites sampled in August, consistent with abundances observed by HABMAP at piers, and in stark contrast to the very high abundances observed in July. This led to the lifting of shellfish safety notifications in San Mateo and San Francisco Counties due to the threat of Paralytic Shellfish Poisoning. However, warnings for PSP in mussels remained for Santa Cruz and Monterey Counties.

*Please note that HABMAP sampling, CDPH sampling, and marine mammal rescues have been greatly reduced in response to COVID-19 safety measures.  

Santa Cruz Wharf

Water samples were collected at Santa Cruz Wharf 3 times in August. Molecular probes for toxigenic Pseudo-nitzschia in the "seriata" class are conducted for this site, and were not detected. Alexandrium spp. were not detected during the sampling period. Domoic acid results are not yet available.

The Santa Cruz Wharf shore station is supported by CeNCOOS PI Raphael Kudela at UCSC.

Monterey Wharf

Water sampling has been suspended at Monterey Wharf since March 2020 in response to COVID-19 safety measures. 

Monterey Wharf shore station is supported by CeNCOOS PI's Raphael Kudela at USCS and Jason Smith and Moss Landing Marine Labs.

Cal Poly Pier

Water samples were collected four times at Cal Poly Pier in August. Pseudo-nitzschia "delicatissima" was detected above bloom levels on August 3 and 10. Pseudo-nitzschia "seriata" was not detected in any samples. Alexandrium spp. were detected in three of the four water samples. Domoic acid results are not yet available. 

Cal Poly Pier shore station is supported by SCCOOS PI Ryan Walter and Ally Pasulka at Cal Poly. 

Stearns Wharf

Water samples were collected two times at Stearns Wharf Pier in August. Pseudo-nitzschia "delicatissima" was not detected above bloom levels while Pseudo-nitzschia "seriata" was above bloom values on August 3. Alexandrium spp. were detected in one of the two water samples. Domoic acid results are not yet available. 

Stearns Wharf is supported by SCCOOS PI Mark Brzezinski and Libe Washburn at UCSB. 

Santa Monica Pier

Water samples were collected four times at Santa Monica Pier in August. Pseudo-nitzschia "delicatissima" and Pseudo-nitzschia "seriata" were not detected above bloom levels. Alexandrium spp. were not detected in any samples and domoic acid results are not yet available. 

Santa Monica Pier shore station is supported by SCCOOS PI Rebecca Shipe at UCLA.

Scripps Pier

Scripps Pier water samples are not yet available for April through August 2020. 

Scripps Pier is supported by SCCOOS and PIs Melissa Carter and Clarissa Anderson at UCSD.