CALIFORNIA DEPT.OF PUBLIC HEALTH ENVIRONMENTAL MANAGEMENT BRANCH Marine Biotoxin Monitoring Report June 2017 Technical Report No. 17-19 INTRODUCTION: The aptly named Mussel Shoals sampling locaon, with Rincon Island in the This report provides a summary of biotoxin acvity for the month of June, 2017. Toxin concentraon ranges are provided for the paralyc shellfish poi- soning (PSP) toxins and for domoic acid (DA). Es- mates are also provided for the distribuon and relave abundance of Alexandrium, the dinoflagel- late that produces PSP toxins, and Pseudo- nitzschia, the diatom that produces domoic acid. Summary informaon is also provided for any quaranne or health advisory in effect during the reporng period. Please note the following convenons for the phy- toplankton and shellfish biotoxin distribuon maps: (I) All esmates for phytoplankton relave abundance are qualitave, based on sampling effort and percent composion; (ii) All toxin data are for mussel samples, unless otherwise noted; A chain of the PSP toxin-producing dinoflagellate Alexandrium. (iii) All samples are assayed for PSP toxins; DA anal- yses are performed as needed (e.g., on the basis of detected blooms of the diatoms that produce DA); (iv) Please refer to the appropriate figure key for an explanaon of the symbols used on the maps. background (Photo courtesy of the Ventura County Environmental Health Department). Northern California Summary: Paralyc Shellfish Poisoning Alexandrium was observed at numerous locaons between Del Norte and Monterey counes (Figure 1). The relave abundance of this dinoflagellate was highest in a sample collected offshore of Pt. Pinos in Monterey County and, to a lesser extent, in samples from outer Tomales Bay and near the Golden Gate in San Francisco Bay. Cell numbers were low at all oth- er sites. PSP toxicity was detected in shellfish from sites in Del Norte, Humboldt, Marin, and Monterey counes (Figure 2). The highest concentraon of toxin detect- ed was in sennel mussels from Drakes Bay (Marin County), which contained 322 ug/100 g (June 26). Low levels of this toxin were detected in sennel mussels near the mouth of Humboldt Bay during the second and third weeks of the month. Low concen- traons of the PSP toxins connued to be detected throughout the month in samples of rock scallop vis- cera from the Monterey Commercial Wharf. (Connued on page 2)
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CALIFORNIA DEPT.OF PUBLIC HEALTH ENVIRONMENTAL MANAGEMENT BRANCH
Marine Biotoxin Monitoring Report June 2017 Technical Report No. 17-19
INTRODUCTION: The aptly named Mussel Shoals sampling location, with Rincon Island in the
This report provides a summary of biotoxin activity
for the month of June, 2017. Toxin concentration
ranges are provided for the paralytic shellfish poi-
soning (PSP) toxins and for domoic acid (DA). Esti-
mates are also provided for the distribution and
relative abundance of Alexandrium, the dinoflagel-
late that produces PSP toxins, and Pseudo-
nitzschia, the diatom that produces domoic acid.
Summary information is also provided for any
quarantine or health advisory in effect during the
reporting period.
Please note the following conventions for the phy-
toplankton and shellfish biotoxin distribution
maps: (I) All estimates for phytoplankton relative
abundance are qualitative, based on sampling
effort and percent composition; (ii) All toxin data
are for mussel samples, unless otherwise noted;
A chain of the PSP toxin-producing dinoflagellate Alexandrium.
(iii) All samples are assayed for PSP toxins; DA anal-
yses are performed as needed (e.g., on the basis of
detected blooms of the diatoms that produce DA);
(iv) Please refer to the appropriate figure key for
an explanation of the symbols used on the maps.
background (Photo courtesy of the Ventura County Environmental Health
Department).
Northern California Summary:
Paralytic Shellfish Poisoning
Alexandrium was observed at numerous locations
between Del Norte and Monterey counties (Figure
1). The relative abundance of this dinoflagellate was
highest in a sample collected offshore of Pt. Pinos in
Monterey County and, to a lesser extent, in samples
from outer Tomales Bay and near the Golden Gate in
San Francisco Bay. Cell numbers were low at all oth-
er sites.
PSP toxicity was detected in shellfish from sites in
Del Norte, Humboldt, Marin, and Monterey counties
(Figure 2). The highest concentration of toxin detect-
ed was in sentinel mussels from Drakes Bay (Marin
County), which contained 322 ug/100 g (June 26).
Low levels of this toxin were detected in sentinel
mussels near the mouth of Humboldt Bay during the
second and third weeks of the month. Low concen-
trations of the PSP toxins continued to be detected
throughout the month in samples of rock scallop vis-
cera from the Monterey Commercial Wharf.
(Continued on page 2)
(Continued from page 1)
Page 2 June 2017 Technical Report No. 17-19
Domoic Acid
Pseudo-nitzschia was observed at sites in each
northern California coastal County in June (Figure
1). The relative abundance of this diatom increased
at sites in Del Norte, Humboldt, Santa Cruz, and
Monterey counties compared to observations in
May. The highest relative abundance of this diatom
was observed in a sample collected offshore of Pt.
Pinos (Monterey County), the same sample with
significant numbers of Alexandrium as noted
above. Elevated relative abundances of Pseudo-
nitzschia were also observed in samples from Wil-
son Creek (Del Norte County) on June 26 and at In-
dian Island inside Humboldt Bay on June 27.
High concentrations of domoic acid were detected
in mussel samples from Hunter’s Rock in northern
Del Norte County (25 ppm on June 30) and from
the Commercial Wharf in Monterey
County (55 ppm on June 6). Low con-
centrations of this toxin were also de-
tected in mussels from Wilson Creek,
outer Humboldt Bay, and the Santa
Cruz Pier.
Very high concentrations of domoic
acid continued to be detected in razor
clams from Humboldt County in June
(Figure 2). Toxin concentrations ex-
ceeded the alert level in 10 of 11 clam
samples from Clam Beach, with the
highest concentration being 120 ppm. (Continued on page 4)
Figure 1. Toxic phytoplankton distribution in northern California.
Page 3 June 2017 Technical Report No. 17-19
Figure 2. Distribution of shellfish biotoxins in northern California.
Page 4 June 2017 Technical Report No. 17-19
(Continued from page 2) Figure 3. Toxic phytoplankton distribution in southern California.
Six of 11 clam samples
from Little River State
Beach exceeded the alert
level for domoic acid, with
the highest concentration
being 85 ppm.
The CDPH Food and Drug
Branch collected samples
of rock crab fished from
offshore of Shelter Cove in
southern Humboldt Coun-
ty. The crab viscera con-
tained varying concentra-
tions of domoic acid, rang-
ing from nondetectable to 73 ppm.
Non-Toxic Species
Diatoms continued to dominate the northern
California phytoplankton assemblage, with Chaetoceros and Skeletonema ubiquitous along most of
the coast.
Southern California Summary:
Paralytic Shellfish Poisoning:
Alexandrium was observed at several sites between San
(Continued on page 5)
The Marine Biotoxin Monitoring and Control Program, managed by the California Department of Public
Health, is a state-wide effort involving a consortium of volunteer participants. The shellfish sampling and
analysis element of this program is intended to provide an early warning of shellfish toxicity by routinely as-
sessing coastal resources for the presence of paralytic shellfish poisoning (PSP) toxins and domoic acid.
The Phytoplankton Monitoring Program is a state-wide effort designed to detect toxin producing species of
phytoplankton in ocean water before they impact the public. 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.
For Information on Volunteering: For Recorded Biotoxin Information Call: