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 around throughout coastal California from the Santa Barbara Channel to the Oregon border in July, a pattern in the C-HARM model that has persisted for some years. This indicates that C-HARM is predicting positive habitat suitability for Pseudo-nitzschia most of the year 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. Bloom probabilities in the Southern California Bight trended high throughout the month, although confined more to the nearshore zone and with higher spatial and temporal variability, increasing in intensity at the end of July. While COVID-19 sampling restrictions continue to hamper our ability to acquire HABMAP observations from piers, we do know that the more toxigenic Pseudo-nitzschia "seriata" size class approached or surpassed the bloom threshold at the Santa Cruz Wharf for most of July, consistent with the high C-HARM bloom probabilities for Monterey Bay. 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, coinciding with very high bloom probability close to shore in the SLO region at the end of July. The only southern California sites where we have observations for all of July are the Santa Monica and Newport Beach Piers. Pseudo-nitzschia spp. were not recorded during weekly sampling at the Santa Monica Pier. In contrast, at Newport Beach Pier, the Pseudo-nitzschia "delicatissima" size class was at or above bloom levels most of the month, while the more toxigenic Pseudo-nitzschia "seriata" size class approached bloom levels at the end of the month. HABMAP samples were either not collected or data are not yet available for Monterey Wharf, Stearns Wharf, and Scripps Pier.  The highest abundances of the Pseudo-nitzschia "seriata" size class recorded by the CDPH were located near SLO and Santa Cruz.

Moderate to very high probabilities (60-100%) of particulate DA (pDA) were predicted for most of the California coast throughout July, with greater offshore extent than in previous months. South of the Santa Barbara Channel, pDA was often predicted to well exceed the 500 ng/L threshold but with a patchy distribution throughout the Bight, and as with Pseudo-nitzschia predictions, confined closer to shore.  Probabilities 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 was a relative hot spot experiencing persistently high pDA probabilities throughout July. While much of the elevated pDA probabilities extended very far offshore, much like in May & June, 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, with local minima near Sonoma and also in the same zone near SLO where the pDA minima occurred. In general, patterns seen in the pDA output were mirrored by the cDA model but also skewed higher or more extreme, with higher maxima and lower minima. The consistently high probabilities for pDA along the central coast and parts of LA in the Bight are consistent with the six California Sea Lion strandings from suspected DA toxicosis reported by The Marine Mammal Center (TMMC) from San Mateo to SLO Counties in July. One California sea lion stranded in the LA area from suspected DA toxicosis at the end of July as reported by the Marine Mammal Care Center of Los Angeles. This is consistent with the C-HARM predictions of high pDA and high cDA in that region. The only available domoic acid measurements from HABMAP during July were collected at Santa Cruz Wharf and indicated no DA at that site, as has been the case for a year or more. This is inconsistent with C-HARM predictions for pDA but largely consistent for cDA in the Monterey Bay area. Measurements of DA are not yet readily available in the Humboldt region for HABMAP, but the pDA and cDA predictions from C-HARM are consistent with the health advisories issued by the CDPH for domoic acid in razor clams in Del Norte and Humboldt Counties.

Alexandrium -  CDPH noted that Alexandrium spp. were very abundant in the SLO region, Morro Bay, and Santa Cruz Wharf in July, consistent with similarly high (and alarming) abundances observed by HABMAP at Santa Cruz Wharf and Cal Poly Pier. Subsequent evaluation of saxitoxin in shellfish led the CDPH to issue health advisories for mussels, clams, and whole scallops in San Mateo, San Francisco, Santa Cruz, and Monterey Counties due to the threat of Paralytic Shellfish Poisoning.

*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 five times in the month of July. Molecular probes for toxigenic Pseudo-nitzschia in the "seriata" class are conducted for this site, and was not detected. Alexandrium spp. were not detected above bloom levels at any time during the sampling period. Domoic acid was not detected in the water samples.  

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

Monterey Wharf

Water samples have 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 the month of July. Pseudo-nitzschia "delicatissima" was detected above bloom levels on July 27th. 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. 

Water samples have been suspended at Stearns Wharf since March 2020 in response to COVID-19 safety measures. 

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 the month of July. Pseudo-nitzschia "delicatissima" and Pseudo-nitzschia "seriata" were not detected in any of the water samples. Alexandrium spp. were detected at low levels on July 27th 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 July 2020. 

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