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). Predicted suitable habitat for Pseudo-nitzschia spp. was spread around throughout coastal California in May, much like in previous months, with more widely distributed high probabilities for Pseudo-nitzschia blooms spread throughout the state. In general, the central coast from Monterey Bay to Pt. Conception and the SB Channel exhibited persistently high bloom probabilities. Bloom probabilities in the Southern California Bight were also high throughout the month, particularly in the nearshore zone. 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 reached abundances well above the bloom threshold at the Santa Cruz Wharf towards the end of May, consistent with the high C-HARM bloom probabilities for the Monterey Bay. Observed bloom levels of the less toxigenic Pseudo-nitzschia "delicatissima" size class at Cal Poly Pier were also consistent with the central CA peaks in bloom probability throughout May. The only southern California site where we have available observations in May is the Santa Monica Pier where there was no Pseudo-nitzschia activity despite high C-HARM probabilities in the LA county region during most of the month. The massive red tide of Lingulodinium polyedra that pervaded the region from northern Ventura County to Baja, starting at the end of March and peaking in mid-May, could account for elevated chlorophyll or high remote sensing reflectance in this area during April and May. These anomalous remote sensing retrievals could have created false positives in the Pseudo-nitzschia bloom model for the Southern California Bight. It should also be noted, however, that robotic microscope (IFCB) data presented from the Del Mar mooring about 3 nautical miles offshore of San Diego shows that Pseudo-nitzschia spp. was common in shelf waters even at the height of the bloom.
Moderate to high probabilities of particulate DA (pDA) were predicted for most of the California coast throughout May, with the Humboldt and Mendocino coast waxed and waned in terms of intensity, especially in offshore waters near the Oregon border where the risk of high pDA was predicted to be very low. Probabilities from Sonoma and Marin County to San Luis Obispo County were fairly consistently high for pDA for the first half to the month, consistent with the 16 California Sea Lion strandings reported by The Marine Mammal Center (TMMC) from mid to late May from Marin to San Luis Obispo Counties. The only available domoic acid measurement from HABMAP during May was collected at Santa Cruz Wharf and indicated no DA there at the end of May. Much of the elevated pDA probabilities extended very far offshore while the high cDA risk appeared to be contained in a fairly tight nearshore band for much of the coastline. The Southern California Bight saw elevated cDA probabilities that peaked in mid-May and occasionally grew intense in the Santa Barbara Channel, Los Angeles, and San Diego regions, consistent with one California Sea Lion stranding from suspected DA toxicosis reported from the Pacific Marine Mammal Center (PMMC) at the end of May.
CDPH reported moderate to high percent composition for the Pseudo-nitzschia "seriata" size class near Tomales Bay (Marin County), Pacifica Pier (SF County), and Santa Cruz Wharf (SC County), consistent with C-HARM predictions along the central coast.
Alexandrium - CDPH noted that Alexandrium spp. were in very low abundance or absent from all sites samples in California, consistent with the HABMAP sampling at Santa Cruz Wharf, Cal Poly Pier, and Santa Monica Pier.
**Please note that HABMAP sampling, CDPH sampling and marine mammal rescues have been greatly reduced in response to COVID-19 safety measures.
**HABMAP sampling has been suspended since March 19th in accordance with the Governor's stay at home order to protect the health and well-being of all Californians and to help slow the spread of COVID-19. Cal Poly and Scripps received an exception to continue collecting water samples for the State and are taking the necessary safety measures to protect field personnel. The water samples are being preserved for future analysis by the Caron or Kudela Labs for domoic acid and Brzezinski/UCSB Marine Analytical Labs for macronutrients when it is safe for lab personnel to do so.**
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.
Water samples were collected twice at Santa Cruz Wharf in the month of May. Molecular probes for toxigenic Pseudo-nitzschia in the "seriata" class are conducted for this site, and was detected above bloom levels on May 12th. Alexandrium spp. were detected below bloom levels on May 5th and May 12th. Domoic acid results are not yet available for May. Santa Cruz Wharf does not count for Pseudo-nitzschia delicatissima group.
The Santa Cruz Wharf shore station is supported by CeNCOOS PI Raphael Kudela at UCSC.
Please note CDPH recently moved to only reporting Pseudo-nitzschia of the seriata complex and not all Pseudo-nitzschia spp. as previously provided.
From 1-31 May 2020, 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 53 of the 80 samples. Pseudo-nitzschia seriata was detected at "Abundant" density levels (using CDPH relative abundance index) on May 31st at Pacific Pier in San Mateo County (50% composition). Alexandrium spp. were detected in 9 of the 80 samples in the month of May at low-density levels (<0.5% composition).
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 weekly map layers of Pseudo-nitzschia and Alexandrium spp. here.
Data are provided by the California Department of Public Health, Environmental Management Branch.
CDPH and OEHHA Health Advisories
California Department of Public Health (CDPH) annual quarantine of sport-harvest mussels began May 1, 2020. The quarantine is in place to protect the public against poisoning that can lead to serious illness, including coma and death. For the latest closures and updates, please visit the CDPH Health Advisories page as a central location of information related to CDPH and/or OEHHA health advisories.
On July 30, 2019 the Office of Environmental Health Hazard Assessment (OEHHA) hosted the Domoic Acid Webinar: Research on Effects of Repeat Low-Level Exposures and Its Implications for Human Toxicity. The recorded webinar can be found here.
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 May a total of 17 marine mammal strandings presented with symptoms of domoic acid toxicosis.
The Channel Islands Marine Wildlife Institute (CIMWI), California Wildlife Center (CWC), Marine Animal Rescue (MAR), Marine Mammal Care Center-Los Angeles (MMCC-LA), and SeaWorld did not record any strandings due to suspected domoic acid in May 2020.
April strandings due to suspected DA toxicosis occurred in the following counties:
- Marin County (TMMC)
- May 20th - adult, female, California Sea Lion
- Stanislaus County (TMMC)
- May 17th - subadult, male, California Sea Lion
- San Mateo County (TMMC)
- May 17th - adult, female, California Sea Lion
- May 18th - juvenile, male, California Sea Lion
- May 30th - juvenile, male, California Sea Lion
- May 30th - subadult, male, California Sea Lion
- Santa Cruz County (TMMC)
- May 17th - juvenile, male, California Sea Lion
- May 29th - adult, female, California Sea Lion
- May 29th - juvenile, male, California Sea Lion
- Monterey County (TMMC)
- May 14th - pup, female, California Sea Lion
- May 15th - subadult, male, California Sea Lion
- May 18th - adult, female, California Sea Lion
- May 24th - adult, female, California Sea Lion
- May 24th - adult, female, California Sea Lion
- May 28th - adult, female, California Sea Lion
- San Luis Obispo County (TMMC)
- May 15th - adult, female, California Sea Lion
- Orange County (PMMC)
- May 26th - adult, female, California Sea Lion