May 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 May, being observed in only one of 48 northern California phytoplankton samples (Figure 1). This dinoflagellate was present (2%) in a May 9 sample from inside Humboldt Bay.
PSP toxicity was not detected in any mussel or oyster samples in May (Figure 2).
Domoic Acid
Pseudo-nitzschia was observed in 21 of 48 samples representing most coastal counties (Figure 1). The percent composition of this diatom decreased inside Monterey Bay at both the Santa Cruz Wharf and the Seacliff Pier, while increasing at the Pacifica Pier (10% and 5%, May 22 and 29, respectively). The cell mass was low in all samples.
Razor clam samples were collected at Crescent Beach (Del Norte County) on May 15 by volunteer Ken Graves. One of three clam samples contained a concentration of domoic acid (26 ppm) in exceedance of the alert level, with two additional samples containing low levels of this toxin (13 ppm and 5.1 ppm). The Tolowa Dee-ni’ Nation collected four clam samples at Crescent Beach on May 21, three of which exceeded the alert level (20 ppm, 27 ppm, and 30 ppm). The fourth sample contained a low level of domoic acid (8.6 ppm).
Domoic acid was not detected in any mussel or oyster samples in May.
Non-Toxic Species
A variety of diatoms was observed along the northern California coast in April. Thalassiosira was common to abundant at sites between Humboldt and San Mateo counties. The greatest cell masses were observed inside Tomales Bay on May 16 and 23 (50% and 75%, respectively). Skeletonema was common at sites between Marin and Monterey counties. Chaetoceros was common at sites in Humboldt, Contra Costa, and San Mateo counties and was abundant (78%) in a May 12 sample from approximately 25 miles offshore of Davenport in Santa Cruz County. The lone common dinoflagellate was Noctiluca, which was common at the Pacifica Pier (40%, May 1).
This month’s photos highlight two diatoms, one common and one rare. Chaetoceros was observed in 32 of 44 samples and Asteromphalus in just five samples.
Southern California Summary
Paralytic Shellfish Poisoning
Alexandrium increased slightly in frequency of occurrence, being observed in seven of 44 southern California samples (Figure 3). The percent composition of this dinoflagellate was slightly elevated (2%) in a May 13 sample from offshore of Rocky Point in Los Angeles County.
PSP toxins continued to be detected at low concentrations in mussel samples from the Goleta Pier and an aquaculture lease offshore of Santa Barbara in May (Figure 4). Low level toxicity was also detected in a May 21 mussel sample from Leo Carrillo State Beach in northern Los Angeles County (51 µg/100 g).
Domoic Acid
Pseudo-nitzschia relative abundance decreased slightly in May, although it continued to be observed in samples from each southern California coastal county (Figure 3). This diatom was observed in 8 of 44 samples, with the greatest percent composition observed on samples from Avalon Bay, Catalina Island (11%, May 8) and the Imperial Beach Pier in San Diego County (12%, May 3).
Domoic acid was not detected in any mussel or oyster samples in May (Figure 4).
Non-Toxic Species:
Diatoms were predominant in samples from San Luis Obispo to Ventura counties. The diatom Chaetoceros was abundant is a May 6 sample from the San Simeon Pier (63%) and common elsewhere. Thalassiosira was abundant inside Morro Bay (60%, May 16) and common offshore of Diablo Cove in San Luis Obispo County. Eucampia was abundant at the latter site (56%) and common at Goleta Pier and Port Hueneme Pier.
Dinoflagellates were increasingly common in samples between Los Angeles and San Diego counties. Lingulodinium polyedrum was observed throughout this range, being abundant in samples from offshore of Rocky Point (54%, May 13) and the San Clemente Pier (65%, May 31). Akashiwo sanguineum was common (20%) inside Santa Monica Bay and Prorocentrum micans was abundant at the Imperial Beach Pier (52%, May 26). The cell mass was low for all samples.
This month’s photos highlight the dinoflagellate Dinophysis fortii and the diatom Leptocylindrus, which were observed in nine and 15 of 44 samples, respectively.
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 June 1, 2022. For access to current advisories, please refer to the end of this report.
● On April 26 CDPH announced the May 1 start of the annual quarantine of sport-harvested mussels gathered along the California coast. The quarantine applies to all species of mussels that are recreationally harvested for human consumption along the California coast, including all bays and estuaries. During the quarantine, mussels may only be harvested for use as bait. The quarantine is in place to protect the public against poisoning that can lead to serious illness, including coma and death.
● 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.
