November 2021 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 was observed at sites in each coastal county between Mendocino and Monterey (Figure 1). This dinoflagellate was observed in 15 of 40 northern California phytoplankton samples. The percent composition of Alexandrium was slightly elevated inside Monterey Bay at the Santa Cruz Wharf (1%, November 24) and the Monterey Commercial Wharf (1%, November 1). The cell mass was low at all sites.
PSP toxicity was detected in several shellfish samples in November (Figure 2). Low toxin concentrations were detected in mussel samples from sites in Del Norte, Sonoma, Marin, San Mateo, Santa Cruz, and Monterey counties. The highest concentration detected was 55 µg/100g on November 2 at China Rock in Monterey County.
Domoic Acid
Pseudo-nitzschia was observed in all coastal counties between Humboldt and Monterey (Figure 1). This diatom occurred in 17 of 40 northern California samples. The percent composition and cell mass of Pseudo-nitzschia was low in all samples.
Domoic acid was not detected in any mussel or oyster samples in November (Figure 2).
Non-Toxic Species
Phytoplankton relative abundance declined in November, with a mix of diatoms and dinoflagellates observed mostly in protected waters. The diatoms Chaetoceros and Thalassionema were common inside Humboldt Bay, while the dinoflagellate Akashiwo sanguineum was abundant at the Pacifica Pier (52%, November 20) and common in Tomales Bay and at the Monterey Commercial Wharf. Prorocentrum micans was common in outer Tomales Bay and Gymnodinium spp. were common at the Monterey Wharf and abundant at the Santa Cruz Wharf (60%, November 3). Two of the less common species observed in November and featured in this month’s photos were the diatom Tropidoneis and the dinoflagellate Phalacroma rotundatum (= Dinophysis rotundata).
Southern California Summary
Paralytic Shellfish Poisoning
Alexandrium continued to be observed at numerous sites along the southern California coast in November (Figure 3). The percent composition of this dinoflagellate was slightly elevated in samples from offshore of Diablo Cove (2%, November 18) and at the Goleta Pier (1%, November 9). Alexandrium was observed in 17 of the 45 phytoplankton samples collected in this region; the cell mass was low in all samples containing Alexandrium.
Low concentrations of PSP toxins, just above the detection limit, were present in oysters from inner Morro Bay throughout most of the month (Figure 4). Low toxin levels were also detected in mussels from the Cal Poly Pier (37 µg/100 g, November 1) and Pt. Mugu in Ventura County (33 µg/100 g, November 5).
Domoic Acid
Low numbers of Pseudo-nitzschia were observed in samples from all coastal counties except Ventura (Figure 3). This diatom was observed in 15 of the 45 southern California samples.
Domoic acid was not detected in any mussel or oyster samples in November (Figure 4).
Non-Toxic Species:
The dinoflagellate Lingulodinium polyedrum continued to be the most abundant species between Santa Barbara and San Diego counties, occurring in 38 of 45 southern California samples. L. polyedrum was abundant in samples from the following locations: offshore of Naples Pt. (74%, November 19); Goleta Pier (50%, November 2); Santa Monica Pier (90%, November 12); offshore of Pt. Dume (60%, November 27); offshore of Palos Verdes (89% and 73%, November 13 and 28, respectively); Cabrillo Beach (79%, November 30); San Clemente Pier (76%, November 30); outer Agua Hedionda Lagoon (92%, November2); and Scripps Pier (56%, November 15). The greatest cell masses of L. polyedrum were observed in the samples from Santa Monica Pier and Agua Hedionda Lagoon. The dinoflagellates Akashiwo sanguineum and Ceratium furca were common offshore of Diablo Cove. The diatom Chaetoceros was common in a sample from the Imperial Beach Pier.
Also observed in a small number of samples, and featured in this month’s photos, were the heterotrophic dinoflagellate Polykrikos sp. and the diatom Lithodesmium.
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
Mussel sampling location (rocky outcrop in distance) in the vicinity of El Capitan and Refugio beaches in Santa Barbara County (photo courtesy of Melinda Mettler).
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 December 1, 2021. For access to current advisories, please refer to the end of this report.
On October 29 CDPH announced that the statewide annual quarantine on mussels gathered by sport harvesters from California's ocean waters would end at midnight on Saturday, October 31, 2021, for all coastal counties.
On October 5 CDPH lifted the August 27 PSP warning related to sport-harvested clams and scallops in Marin County.
● On August 27 CDPH warned consumers not to eat sports-harvested mussels, clams, or scallops from Marin County due to elevated levels of the PSP toxins.
● On August 11 CDPH lifted the August 2015 warning related to dangerous levels of domoic acid in sport-harvested razor clams in Humboldt County. Domoic acid, also referred to as Amnesic Shellfish Poisoning, can cause illness or death in humans. Razor clams are known to retain domoic acid in their meat and tissues much longer than other species of bivalve shellfish. Recent testing confirmed that concentrations of domoic acid are now at safe or undetectable levels in razor clams as well as other species of bivalve shellfish.
● On May 3 CDPH lifted the August 2015 warning related to dangerous levels of domoic acid in sport-harvested razor clams in Del Norte County.
● On April 30 CDPH announced the annual quarantine of sport-harvested mussels gathered along the California coast. The quarantine began on May 1 and applies to all species of mussels that are recreationally harvested for human consumption along the California coast, including all bays and estuaries. The quarantine will extend through midnight October 31, although it can be extended if dangerous PSP toxin levels persist in shellfish. Historically the majority of human cases of PSP illnesses occur between spring and fall. In California, PSP is extremely rare due to the efforts put forth by CDPH to protect the public against poisoning. There have been no reported human cases of domoic acid poisoning in California.
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.
