California HAB Bulletin: February 2021

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 the deadly neurotoxin, domoic acid (DA). The predicted suitable habitat for Pseudo-nitzschia spp. in February 2021 (note: model imagery only available Feb 11-Feb 26) suggested widespread suitability throughout the state for Pseudo-nitzschia to grow and reach bloom levels as in January but with some notable differences. In particular, there was a shift over the course of the month in the magnitude of bloom predictions from the northern regions of California, which had a very high likelihood of blooms in January, to central CA and the Santa Barbara Channel Islands region and into most of the Southern California Bight by mid-late February. Generally, though, C-HARM is still predicting positive habitat suitability for the genus Pseudo-nitzschia in most parts of coastal California much of the time, something that is corroborated by the frequent presence of Pseudo-nitzschia species in water samples at nearshore sites in most months. Given ongoing COVID-19 sampling restrictions and delays that continue to hamper our ability to acquire timely HABMAP observations from piers, not all piers are currently providing data, but we do know that Pseudo-nitzschia abundance above bloom levels was observed for both the toxigenic size class of Pseudo-nitzschia at Santa Monica Pier and well above bloom levels for both the toxigenic and non-toxigenic size classes at Newport Beach Pier by the end of February. Levels fell below the bloom threshold at Cal Poly Pier in San Luis Obispo during the month of February, although early March sampling caught a spike in the toxigenic size class. The Relative Abundance Index (RAI) for the Pseudo-nitzschia 'seriata' size class recorded by the CDPH reached moderate levels ("Common") in and around San Francisco and Tomales Bays, Santa Cruz Wharf, San Luis Obispo, Santa Barbara area, at sites throughout Los Angeles County and Orange County offshore.

Moderate to very high C-HARM probabilities (50-100%) for particulate domoic acid (pDA) were predicted at different times for several sections of the California coastline in February with a focus on the central coast. As the month progressed, zones of high pDA likelihood, or "hotspots," intensified along the Mendocino and Sonoma coastlines, around San Francisco Bay, the central coast between Monterey Bay and San Luis Obispo (but not including the MB), Pt. Conception and the Santa Barbara Channel, and much of the Southern California Bight to San Diego. HABMAP particulate domoic acid data are not yet available for February. Similar patterns were predicted for cellular DA (cDA) risk as those for pDA, although often with more intensity and further offshore; parts of the Santa Barbara Channel and Southern California lit up towards the end of February. This breaks a season-long trend whereby cDA probabilities were frequently high along the North and Sonoma Coasts, suggesting a possible subsidence in severe domoic acid problems along the North Coast. However, a razor clam health advisory is still in effect for Humboldt and Del Norte Counties due to domoic acid. As in January, the very high probabilities for pDA (and cDA) in central coast hotspots in February are consistent with the two California Sea Lion strandings from suspected DA toxicosis in San Luis Obispo and Monterey Counties reported by The Marine Mammal Center (TMMC); no other regions reported suspected DA toxicosis cases in February.

Alexandrium -  CDPH observed very low abundances of Alexandrium spp. at sites sampled in February, consistent with HABMAP sampling. The CDPH lifted a recreational shellfish advisory for Marin County related to PSP on February 8th.

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

C-HARM Model

Probability of Pseudo-nitzschia Bloom for February 2021

Probability of Particulate DA for February 2021

Probability of Cellular DA for February 2021

Harmful Algal Bloom Monitoring & Alert Program (HABMAP) 

**HABMAP sampling resumed after being suspended in March 2020 in accordance with the Governor's stay at home order. However, COVID-19 safety protocols and sampling restrictions may continue to affect operations and delay results.**

Note that data for some stations are not shown because they are not yet recorded in the public HABMAP archive.

Differentiating Pseudo-nitzschia species by light microscopy is difficult. For this reason, Pseudo-nitzschia "seriata" does not refer to an actual species but rather the larger size class of Pseudo-nitzschia, which is generally a more toxigenic group of species. Alternatively, Pseudo-nitzschia "delicatissima" refers to the smaller size class that is generally non-toxigenic. The dashed line on the plots demarcates the 10,000 cells/L "bloom" threshold designated here for Pseudo-nitzschia populations only.

More information and data visualizations on the statewide HAB network and forecasting system can be found on the California HABMAP website and on the SCCOOS Harmful Algal Bloom page.  

Santa Cruz Wharf

Three water samples were collected at Santa Cruz Wharf in February. Molecular probes for toxigenic Pseudo-nitzschia in the "seriata" class are conducted for this site, and was detected twice: once on Feb 17 (below the bloom threshold level) and on Feb 24 (above the threshold). Alexandrium spp. were detected once on Feb 24 (below the bloom threshold). 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

Three water samples were collected at Cal Poly Pier in February. Pseudo-nitzschia "delicatissima" was detected each time (Feb 8, 15, 22) and Pseudo-nitzschia "seriata" was detected once (Feb 22). All detections were below the bloom threshold value in February. However, Pseudo-nitzschia "seriata" ramps up and exceeds bloom thresholds values on March 1. Alexandrium spp. were not detected in any 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. 

Monterey Wharf

No samples were collected at Stearns Wharf in February.

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

Santa Monica Pier

Two water samples were collected at Santa Monica Pier in February. Pseudo-nitzschia "delicatissima" was detected once on Feb 15 (below bloom threshold). Pseudo-nitzschia "seriata" was detected on Feb 8 (below threshold) and Feb 15 (above threshold). Alexandrium spp. were not detected and domoic acid results are not yet available. 

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

Newport Pier

Three water samples were collected at Newport Beach Pier in February. Pseudo-nitzschia "delicatissima" and Pseudo-nitzschia "seriata" were detected above bloom threshold values on every occasion (Feb 8, 15, 22). Alexandrium spp. were not detected and domoic acid results are not yet available.

Newport Beach Pier is supported by SCCOOS PI David Caron at USC.

Scripps Pier

Scripps Pier water samples are not available for April through February 2021.

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

CDPH observations for Pseudo-nitzschia 'seriata'. and Alexandrium spp.

Please note, starting in July 2019, CDPH moved to only reporting Pseudo-nitzschia of the seriata complex and not all Pseudo-nitzschia spp. as previously provided. 

From 1-28 February 2021, water samples were collected by volunteers and sent to the California Department of Public Health (CDPH) for analysis. Pseudo-nitzschia 'seriata' group was detected in 51 of the 84 samples. Pseudo-nitzschia 'seriata' was detected at "Common" density levels (using CDPH relative abundance index) on 6 occasions: Feb 10 (Goleta Pier 12% composition and Port San Luis 12% composition), Feb 15 (Santa Monica Pier 12%), Feb 21 (Santa Cruz Wharf 10%), Feb 24 (Santa Cruz Wharf 10%), and Feb 26 (Palos Verdes 10%). Alexandrium spp. were detected in 12 of the 84 samples in Feb. Of the 12 samples, all were at the "Rare" density level except for 2 at the "Present" level. Those 2 were found at Drakes Bay on Feb 9 (1.5%) and Santa Barbara Channel on Feb 22 (6%). 

You can view an interactive map and data table of CDPH data from January 2019 to present developed by SCCOOS below or you can also view CDPH Toxic Phytoplankton Observations Map with layers of Pseudo-nitzschia and Alexandrium spp. as well as other phytoplankton species observations (in the pop-up windows).

Data are provided by the California Department of Public Health, Environmental Management Branch.

Please email CDPH at for any potential marine HAB-related illness in humans.

CDPH and OEHHA Health Advisories

February 8. The California Department of Public Health (CDPH) has lifted the December 31, 2020 shellfish safety notification today related to sport-harvested mussels, scallops, and clams in Marin County.

January 12. The California Department of Public Health (CDPH) has lifted the November 18, 2020 shellfish safety notification today related to sport-harvested mussels, whole scallops, and clams in Mendocino County.

December 31. California Department of Public Health (CDPH) is advising consumers not to eat sports-harvested mussels, clams, or scallops from Marin County due to dangerous levels of paralytic shellfish poisoning (PSP) toxins being detected.

For the latest closures and updates, please visit the CDPH Health Advisories page as a central location of information related to CDPH health advisories. Also available is a map showing the current CDPH Recreational Bivalve Shellfish Advisories (see below).

NEWS: The HAB-related illness workgroup has developed a new webpage for marine HAB-related illness tracking work ( 

California Marine Mammal and Seabird Strandings from Suspected DA Toxicosis

Domoic acid (DA) is a potent neurotoxin produced by some diatom species of the genus Pseudo-nitzschia. Species exposed to DA can result in seizures, epilepsy, cardiomyopathy, and death depending upon the ingested dose. DA toxicosis commonly occurs in California Sea Lions (Zalophus californianus), presumably due to a combination of foraging behavior and seasonal movements. The Marine Mammal Center (TMMC), Channel Islands Marine Wildlife Institute (CIMWI), California Wildlife Center (CWC), Marine Mammal Care Center Los Angeles (MMCC-LA), Marine Animal Rescue (MAR), the Pacific Marine Mammal Center (PMMC), and SeaWorld act like an emergency room by working to rescue and rehabilitate sick and injured marine mammals, seabirds, and sea turtles. 

Among the seven rehabilitation centers we received data for in the month of February 2 marine mammal stranding presented with symptoms of domoic acid toxicosis. 

The CIMWI, PMMC, MMCCLA, did not record any strandings due to suspected domoic acid in February 2021.   

February strandings due to suspected DA toxicosis occurred in the following counties:

  • San Luis Obispo (TMMC)
    • February 4 - adult, female, California Sea Lion 
  • Santa Cruz (TMMC)
    • February 23 - juvenile, male, California Sea Lion 

At this time we do not have data from the North Coast Marine Mammal Center.  

Contacts if you find a LIVE stranded animal

Contacts if you find a DEAD stranded animal

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