General Information

Event name: US-04-003
Nature of the harmful event:
High Phyto concentration , Seafood toxins , Mass mortalities
Event directly affected:
Shellfish , Aquatic Mammals
Toxicity detected: Yes (Approximate range: 20 - 170 g/g tissue)
Associated syndrome: ASP
Unexplained toxicity: No
Species implicated in toxin transmission (transvector):
Report the outcome of a monitoring programme: Yes (California Department of Health Services Marine Biotoxin Monitoring Program)
Event occurred before in this location: Yes (Spring event in San Luis Obispo, Santa Barbara typical over the past three years. Spring/summer event in northernmost California (Humboldt and Del Norte counties) resulted in dramatically high concentrations of domoic acid.)
Individuals to contact: LANGLOIS, Gregg

Location & Date

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Location: Latitude: , Longitude:
General location information: South Coast, Central Coast, Northern Coast, California
HAB Area code(s): US-19 US-20 US-21
Additional location information: 1. Santa Barbara County (19): South of Pt. Conception.2. San Luis Obispo County (20): North of Pt. Conception, encompasses Pismo Beach northward to Morro Bay and San Simeon.3. Santa Cruz County (21): North of Monterey, includes shoreline in Monterey Bay and open coast.4. Humboldt County (21): Northern California.5. Del Norte County, Northern California, borders Oregon.
Bloom event dates (yyyy/mm/dd):
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information: March - July 1. Santa Barbara County: DA levels exceed alert level by late April through early May: 87 ppm in mussels and 26 ppm in pacific oysters.2. San Luis Obispo County: Da levels exceed alert level by late March: 45 ppm in mussels, 41 ppm in razor clams. 3. Santa Cruz County: DA level exceeds alert level in mid-April: 26 ppm in mussels.4. Humboldt County: DA concentrations above alert level detected in early June: 120 ppm in razor clams. Peak concentration detected was 170 ppm in razor clam muscle tissue (no viscera included).5. Del Norte County: DA concentration above alert level detected by late May: 33 ppm in razor clams. Elevated levels persisted through early July: 54 ppm


Causative organism known: Yes
Causative Species/Genus: Pseudo-nitzschia spp. ( cells/L)
Co-Ocurring Species/Genus:
Chlorophyll concentration, if known: µg/l
Additional bloom information: 1. Santa Barbara County: Pseudo-nitzschia common from January-May, then July-August. Peak relative abundance observed in early April through first week of May.2. San Luis Obispo County: Highest relative abundance of Pseudo-nitzschia observed by volunteer
Event-related bibliography: Monthly/Annual reports issued by CDHS Marine Biotoxin Monitoring Program

Environmental Conditions

Weather: Turbidity (NTU): Wind direction:
Stratified water: No Oxygen content (nL/L): Wind velocity:
Temperature (°C): Oxygen saturation %: Current Direction:
Sechhi disk (m): Salinity: Current Velocity: 0
Nutrient information:
Temperature Range During Event: Max: °C, Min: °C
Salinity Range During Event:
Bloom location in the water column:
Growth Comments
Additional Environmental information:

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Crassostrea gigas Domoic Acid DA eq 26 ppm Bioassay-Mouse
Mytilus galloprovincialis Domoic Acid DA eq 87 ppm Bioassay-Mouse
Mytilus californianus Domoic Acid DA eq 45 ppm Bioassay-Mouse
Siliqua patula Domoic Acid DA eq 170 ppm Bioassay-Mouse
Kit used: Type of kit used:
Additional information: 170 ppm Jellet rapid extraction kit used on plankton samples HPLC
Economic losses:
Management decision: Harvest closures in commercial aquaculture areas; Health Advisory for sportharvesting of shellfish in Northern California.
Additional harmful effect information: Toxin levels detected in shellfish (primarily mussels, razor clams) and anchovy.
Updated at 01:17 on 10 Oct 2020