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 September, 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 the genus 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, most of the coast in September exhibits 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, as in August. 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 previous months. 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 September. 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 and Stearns wharf, the observed abundance of the both Pseudo-nitzschia size classes showed some uptick in September but never reached bloom levels. The only southern California site where bloom levels were reached was at Newport Beach Pier in Orange County, where the less toxigenic group Pseudo-nitzschia 'delicatissima' exceeded the bloom threshold towards the end of September (noting that data are not yet available for Scripps Pier due to COVID-related delays and personnel challenges). The highest abundances of the Pseudo-nitzschia "seriata" size class recorded by the CDPH were located near San Francisco at Pacifica Pier and near the UC Santa Barbara campus at Goleta Pier.

Moderate to very high probabilities (60-100%) of particulate DA (pDA) were predicted for many parts of the California coast throughout September, maintaining the large offshore extent predicted by C-HARM in previous months. 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, those high probabilities extended far offshore as in August.  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, a pattern that also was seen for large swaths of the Sonoma, Mendocino, and Humboldt coasts in northern California. 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 often, but no 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 probabilities were frequently high along the North and Sonoma Coasts (including areas adjacent to SF Bay), suggesting a possible issue there as seen in August when the North Coast was even more aggressively predicted to be a cDA problem. The frequent and extensive high probabilities for pDA (and cDA) along the central coast and Sonoma County are consistent with the four California Sea Lion strandings from suspected DA toxicosis reported by The Marine Mammal Center (TMMC) from San Mateo, Monterey, and SLO Counties in September; although, note that other regions with high pDA or cDA predictions had no recorded strandings this month. No domoic acid measurements are yet available from HABMAP sampling for September.

Alexandrium -  CDPH recorded low or zero Alexandrium spp. at all sites sampled in September, consistent with abundances observed by HABMAP at piers, and in stark contrast to the very high abundances observed in July when Paralytic Shellfish Poisoning warnings were issued but have since been lifted for all 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 4 times in September. Molecular probes for toxigenic Pseudo-nitzschia in the "seriata" class are conducted for this site, and was not detected during the sampling period. Alexandrium spp. were detected on 15 and 29 of Sept. 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 4 times at Cal Poly Pier in September. Pseudo-nitzschia "delicatissima" and Pseudo-nitzschia "seriata" were detected in only one sample on 28 Sept, below bloom levels. Alexandrium spp. were also detected in 1 sample on 14 Sept. 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 3 times at Stearns Wharf Pier in September. Pseudo-nitzschia "delicatissima" and Pseudo-nitzschia "seriata" were present in each water sample but not above bloom levels. Alexandrium spp. were not detected in any 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 4 times at Santa Monica Pier in September. Pseudo-nitzschia "delicatissima" was detected on 14 and 21 Sept, below bloom levels. Pseudo-nitzschia "seriata" was detected on 7 and 21 Sept, also below 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 September 2020. 

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