March 2022 Marine Biotoxin Monitoring Monthly Report
California Department of Public Health
Introduction
This report contains results from the California Department of Public Health (CDPH) monitoring programs for shellfish toxins and associated toxin-producing phytoplankton. Toxin concentration ranges are provided for the paralytic shellfish poisoning (PSP) toxins and for domoic acid, the latter associated with the syndrome called Amnesic Shellfish Poisoning. Estimates are provided for the distribution and relative abundance of Alexandrium, the dinoflagellate that produces PSP toxins, and Pseudo-nitzschia, the diatom that produces domoic acid. This report also contains summary information for any quarantine or health advisory in effect during the reporting period. Finally, lists of participating agencies and volunteers for each monitoring effort are provided.
Map Notations
Please note the following conventions for the phytoplankton and shellfish biotoxin distribution maps:
(i) All estimates for phytoplankton relative abundance are qualitative, based on sampling effort and percent composition;
(ii) Only known toxin-producing species (e.g., seriata complex for Pseudo-nitzschia) are represented on the maps;
(iii) The relative abundance of Alexandrium and Pseudo-nitzschia are represented by icons that increase in size with increasing relative abundance as shown in the phytoplankton map key to the right.
(i) All toxin data are for mussel samples, unless otherwise noted;
(ii) All shellfish samples are assayed for PSP toxins; DA analyses are performed as needed (e.g., on the basis of detected blooms of the diatoms that produce DA or as part of a continuing surveillance effort);
(iii) Weekly PSP data are represented by four color-coded boxes as shown in the shellfish biotoxin map key to the right;
(iv) Domoic acid data is represented as four weekly color-coded circles overlayed on the PSP boxes.
Northern California Summary
Alexandrium sp.
Paralytic Shellfish Poisoning
Alexandrium distribution and relative abundance remained low in March (Figure 1). This dinoflagellate occurred in only two of 45 northern California phytoplankton samples, being observed in samples from outer Tomales Bay (March 7) and the Monterey Commercial Wharf (March 8).
PSP toxicity was not detected in any mussel or oyster samples in March (Figure 2).
Domoic Acid
Pseudo-nitzschia was observed in 28 of 45 samples representing all coastal counties except Del Norte (Figure 1). This diatom was common at the Pacifica Pier (10%, March 26) and rare or present in all other samples.
Three razor clam samples collected by the Tolowa Dee-ni’ Nation at Crescent Beach (Del Norte County) contained low to moderate concentrations of domoic acid, all below the alert level (17 ppm, 17 ppm, and 8.5 ppm; March 28).
Domoic acid was not detected in any mussel or oyster samples in March.
Non-Toxic Species
Phytoplankton relative abundance increased in March, with diatoms the dominant group along the northern California coast. Chaetoceros was common along most of the coast, being abundant in samples from the Bodega Harbor sentinel station (54%), outer Tomales Bay (70%), and the Monterey Commercial Wharf (73%). Skeletonema was common at multiple sites between Del Norte and San Mateo counties and Thalassiosira was also common throughout much of this range.
Two of the less common species observed in March and featured in this month’s photos are the dinoflagellate Oxytoxum and the diatom Lithodesmium.
Southern California Summary
Paralytic Shellfish Poisoning
Alexandrium was observed in samples from San Luis Obispo, Santa Barbara, Ventura, and San Diego counties (Figure 3), occurring in 10 of 51 southern California samples. The percent composition of this dinoflagellate decreased offshore of Diablo Cove, but increased at Goleta Pier (1%, March 9), compared to observations in February. The cell mass was low in all samples containing Alexandrium.
PSP toxins were detected in shellfish samples from several sites in San Luis Obispo and Santa Barbara counties in March (Figure 4). The low toxicity detected in oysters from inner Morro Bay the latter three weeks of February persisted into the first week of March before declining below the detection limit. In Santa Barbara County, low levels of PSP toxicity were detected in mussels from an offshore aquaculture lease the latter three weeks of March, with an oyster sample also containing a low level of toxins at the end of the month (37 µg/100 g). All measurable levels of PSP toxins were just above the detection limit.
Domoic Acid
Pseudo-nitzschia was observed in 32 of 41 samples, occurring in each coastal county (Figure 3). This diatom was common offshore of Los Angeles in Toyon Bay, Catalina Island (15%, March 7) and at Crystal Cove State Beach in Orange County (15%, March 2). The cell mass was low in all samples.
Domoic acid was not detected in any mussel or oyster samples in March (Figure 4).
Non-Toxic Species:
The diatom Chaetoceros was common to abundant at most sampling sites between San Luis Obispo and San Diego counties. Elevated cell masses of this diatom were observed in samples from Pismo Pier (March 16), Port Hueneme Pier (March 11), and offshore of Palos Verdes (March 9). Eucampia was common at the Pismo Pier and Bacteriastrum was common in samples from the Port Hueneme Pier, Avalon Bay, and Bolsa Chica Lagoon. The dinoflagellate Lingulodinium polyedrum continued to be the most abundant dinoflagellate at sites between Ventura and San Diego counties. The greatest cell masses of L. polyedrum were observed in the samples from the Port Hueneme Pier and offshore of Palos Verdes.
This month’s photos highlight two relatively rare diatoms, Striatella and Pleurosigma (the latter is a darkfield image).
Sampling Effort
The Marine Biotoxin Monitoring and Control Program, managed by the California Department of Public Health, is a state-wide effort involving a consortium of participating organizations, agencies, and volunteer samplers.
The phytoplankton sampling and observation element of the biotoxin monitoring program is a state-wide effort designed to detect toxin producing species of phytoplankton in ocean waters before they impact shellfish resources. The phytoplankton monitoring and observation effort can provide an advanced warning of a potential toxic bloom, allowing us to focus sampling efforts in the affected area before California's valuable shellfish resources or the public’s health is threatened.
Historically, the majority of shellfish toxicity episodes in California have originated along the open coast, occasionally moving into bays and estuaries. The shellfish sampling element of the program provides an early warning of shellfish toxicity by routinely assessing coastal resources for the presence of paralytic shellfish poisoning (PSP) toxins and domoic acid. Routine shellfish sampling is essential for protecting the public from these dangerous toxins.
For Information on Volunteering: Email redtide@cdph.ca.gov or call 510-412-4635
Phytoplankton Samplers
A volunteer collecting a phytoplankton sample.
Phytoplankton samples are primarily collected from coastal piers, although sampling can also be conducted from boat docks and offshore via vessel (kayak, boat). Samples are collected with a plankton net following our standard protocol. The sample bottle and sample collection form are placed in a shipping canister and sent to the CDPH laboratory in Richmond where program staff examine samples with light microscopy. CDPH provides all equipment and prepaid shipping containers.
Shellfish Samplers
A Sonoma County mussel bed.
Mussel samples are routinely collected at one or more representative sampling stations in each coastal county following our standardized protocol. Samplers collect 15-20 individuals and place the shellfish tissue in a sample bottle, which is immediately refrigerated, then frozen overnight. Samples are shipped in an insulated container via 24-hour courier to the department’s laboratory in Richmond for toxin analysis. All materials and shipping are provided by CDPH.
Quarantines, Health Advisories
The following is a list of recent Health Advisories and Quarantines for bivalve shellfish prior to April 1, 2022. For access to current advisories, please refer to the end of this report.
● On December 16 CDPH warned consumers not to eat sport-harvested razor clams from Del Norte County due to the detection of dangerous levels of domoic acid. In addition, CDFW closed the recreational razor clam fishery in Del Norte County on this date, following a recommendation from the Office of Environmental Health Hazard Assessment.
Paralytic Shellfish Poisoning Information:
Consumers of Washington clams, also known as butter clams (Saxidomus nuttalli), are cautioned to eat only the white meat. Washington clams can concentrate the PSP toxins in the viscera and in the dark parts of the siphon and can remain toxic for a long period of time. Persons taking scallops or clams, with the exception of razor clams, are advised to remove and discard the dark parts (i.e., the digestive organs or viscera). Razor clams (Siliqua patula) are an exception to this general guidance due to their ability to concentrate and retain domoic acid in the edible white meat as well as in the viscera.
PSP toxins can produce a tingling around the mouth and fingertips within a few minutes to a few hours after eating toxic shellfish. These symptoms can be followed by disturbed balance, lack of muscular coordination, slurred speech and difficulty swallowing. In severe poisonings, complete muscular paralysis and death from asphyxiation can occur.
Domoic Acid Poisoning Information:
Symptoms of domoic acid poisoning can occur within 30 minutes to 24 hours after eating toxic seafood. In mild cases, symptoms of exposure to this nerve toxin may include vomiting, diarrhea, abdominal cramps, headache and dizziness.
These symptoms disappear completely within several days. In severe cases, the victim may experience excessive bronchial secretions, difficulty breathing, confusion, disorientation, cardiovascular instability, seizures, permanent loss of short-term memory, coma and death.
Sport-harvester Information:
Any person experiencing any of these symptoms should seek immediate medical care. Consumers are also advised that neither cooking or freezing eliminates domoic acid or the PSP toxins from the shellfish tissue. These toxins may also accumulate in seafood species such as crab, lobster, and small finfish like sardines and anchovies.
Sportharvesters should only collect shellfish from areas that are not affected by a current health advisory or quarantine.
Contact the “Biotoxin Information Line” at 1-800-553-4133 or view the recreational bivalve shellfish advisory interactive map for a current update on marine biotoxin activity prior to gathering and consuming shellfish.
