OCTOBER HIGHLIGHTS

*note: for the full suite of HAB taxa sampled weekly, see the SCCOOS and CeNCOOS HABMAP database and the Imaging FlowCytobot Dashboard.

Pseudo-nitzschia -

• C-HARM tells us where conditions are suitable for species of the diatom Pseudo-nitzschia spp. (all size classes) to grow well and where they might be more likely to produce the deadly neurotoxin, domoic acid (DA). Three independent models are run daily to produce nowcasts and three-day forecasts of the probability of a bloom, the probability of a DA event for particulate DA only, and the probability of a DA event for the cellular portion of DA only. Here, in the bulletin, we summarize nowcasts for the month.
• C-HARM predictions for Pseudo-nitzschia spp. blooms in October intensified from September, indicating even more extensive, statewide potential for large blooms, sometimes extending very far offshore north of Pt. Conception.  
• HABMAP pier sampling was again inconsistent with C-HARM given the low Pseudo-nitzschia spp. activity in the nearshore environment, in keeping with recent trends at the piers. Pseudo-nitzschia spp. were rarely detected and only crossed the bloom threshold at three sites for the less 'toxigenic' group P. 'delicatissima': Cal Poly Pier, Stearns Wharf (Santa Barbara), and Scripps Pier (San Diego).  
• Pseudo-nitzschia activity from CDPH coastal sampling, however, detected the more toxigenic size class, Pseudo-nitzschia 'seriata,' as 'Abundant' at northern California sites in Del Norte and Humboldt Counties and "Common" at mostly northern California sites as well as Diablo Cove (San Luis Obispo).
• The CA Imaging FlowCytobot Network images from the piers in October did not detect a Pseudo-nitzschia bloom, consistent with the weekly HABMAP sampling. As reported last month, most sites captured a "red tide" of the bioluminescent dinoflagellate, Lingulodinium polyedra (Santa Barbara to San Diego). Interestingly, and illustrating the power of having real-time plankton community records from IFCBs, the rarely viewed encystement of L. poly cells was also captured over the month of October. This signaled the end of the bloom, although new growth in L. poly did re-appear later in the month as the bloom showed a resurgence. There is significant debate as to whether the observed "planozygotes" are actually cysts or if they are Fragilidinium cf. mexicanum, a heterotrophic dinoflagellate that is known to prey on Lingulodinium polyedra populations (Jeong et al., 1999, Harmful Algae).
• C-HARM probabilities for particulate domoic acid (pDA) at the beginning of October were similar to those at the end of September, with a large eddy of high probabilities off the coast of San Diego suggesting high DA in that region, while areas surrounding Monterey Bay were also very high in risk potential. The central coast in general was predicted to have high pDA risk until mid-October, with some of that focus shifting briefly to areas of the North Coast.
• The pattern for C-HARM predictions of cellular domoic acid (cDA) probability diverged from that of pDA, with high risk areas located in central and northern California rather than the Santa Barbara Channel or further south into the Bight. Cellular toxicity was more likely to be elevated along the Central Coast or the North Coast in a fairly narrow coastal band, with implications for the November Dungeness crab season opener in northern California.
• While results for DA from HABMAP sampling are still pending for September and October at many sites, the year-long trend of no DA at all nearshore stations appears to persist. As noted in the previous bulletin, the strong decoupling with offshore DA was quite apparent during the recent marine mammal mortality event. We now know that that event was driven by high offshore and subsurface DA levels and resulted in incredibly high (possibly record-breaking) DA levels in animal tissue collected from stranded animals.
• Consistent with the high DA risk predicted by C-HARM for the central coast, there were four stranding cases from DA toxicosis reported in the month of October by TMMC from Santa Cruz, Monterey, and San Luis Obispo Counties. This is in contrast to lack of Pseudo-nitzschia spp. activity at the piers in those regions.
• CDPH issued a sport-harvested razor clam health advisory for domoic acid in Del Norte County on November 3rd. Given the low depuration (detox) rates of razor clams, DA levels in razor clams are usually more a reflection of long-term exposure to DA rather than real-time or recent bloom conditions. However, since this same advisory was lifted in June and then reinstated in November of this year, there has likely been persistent, if low-level, production of DA in the North Coast region. Note that the annual quarantine on consuming recreational mussels was still in effect until October 31st.

Alexandrium -

• CDPH detected Alexandrium spp. at background "Present" relative abundance levels at sampling sites throughout central and northern California in October. Meanwhile, a Paralytic Shellfish Poisoning (PSP) advisory initially issued for San Mateo County in early September was extended to Humboldt, Monterey, and San Luis Obispo Counties in October, consistent with observed Alexandrium spp. from CDPH sampling and from HABMAP sampling at Santa Cruz Wharf. However, note that none of the other central CA sites detected Alexandrium spp. in October. 

Summary written by Clarissa Anderson on 21 November 2022

Pseudo-nitzschia "seriata" was detected at "Abundant" density levels on 2 occasions:

• 2022-10-24 70% Hunter Rock, north
• 2022-10-31 70% Humboldt Bay, Indian Is. Ch.

Pseudo-nitzschia "seriata" was detected at "Common" density levels on 5 occasions:

• 2022-10-03 15% Port San Luis, Diablo Cove
• 2022-10-09 25% Trinidad Pier
• 2022-10-10 11% Humboldt Bay, Indian Is. Ch.
• 2022-10-24 10% Humboldt Bay, Indian Is. Ch.
• 2022-10-29 35% Trinidad Pier

Pseudo-nitzschia "seriata" was detected at "Present" density levels on 15 occasions: 

• 2022-10-03 1% Tomales Bay, Lease #M430-15
• 2022-10-03 8% Humboldt Bay, Indian Is. Ch.
• 2022-10-12 3% Goleta Pier
• 2022-10-14 1% Point Dume
• 2022-10-15 3% Pacifica Pier
• 2022-10-17 1% Humboldt Bay, Indian Is. Ch.
• 2022-10-17 9% Morro Bay, Boat Launch
• 2022-10-18 2% Cayucos Pier
• 2022-10-19 1% Goleta Pier
• 2022-10-21 2% San Simeon Pier
• 2022-10-21 4% Port San Luis, Diablo Cove
• 2022-10-24 1% La Jolla, Scripps Pier
• 2022-10-28 5% Port San Luis, Diablo Cove
• 2022-10-28 8% Palos Verdes Rocky Pt Offshore
• 2022-10-31 1% Tomales Bay, Lease #M430-15

Pseudo-nitzschia "seriata" was detected at "Rare" density levels on 12 occasions:

• 2022-10-03 0.5% Morro Bay, Boat Launch
• 2022-10-04 0.5% Mendocino, Noyo Harbor
• 2022-10-05 0.5% Santa Cruz Is., Scorpion Anch.
• 2022-10-10 0.5% Tomales Bay, Lease #M430-15
• 2022-10-15 0.5% San Simeon Pier
• 2022-10-17 0.5% Tomales Bay, Lease #M430-15
• 2022-10-18 0.5% Pismo Pier
• 2022-10-24 0.5% Tomales Bay, Lease #M430-15
• 2022-10-24 0.5% Santa Barbara Ch., Naples Pt
• 2022-10-25 0.5% Santa Cruz Is., Prisoners Hrbr
• 2022-10-26 0.5% Goleta Pier
• 2022-10-31 0.5% San Diego Bay, U.S. Navy Pier

Alexandrium spp. were detected in 20 of the 88 samples: 

Alexandrium spp. were not detected at "Common" density levels. 

Alexandrium spp. were detected at "Present" density levels on 6 occasions: 

• 2022-10-03 1% Port San Luis, Diablo Cove
• 2022-10-03 5% Morro Bay, Boat Launch
• 2022-10-10 5% Tomales Bay, Lease #M430-15
• 2022-10-17 3% Tomales Bay, Lease #M430-15
• 2022-10-19 1% Bodega Harbor, USCG Dock
• 2022-10-21 2% Port San Luis, Diablo Cove

Alexandrium spp. were detected at "Rare" density levels on 14 occasions: 

• 2022-10-03 0.5% Bodega Harbor, USCG Dock
• 2022-10-03 0.5% Tomales Bay, Lease #M430-15
• 2022-10-10 0.3% La Jolla, Scripps Pier
• 2022-10-12 0.5% San Francisco, Presidio Pier
• 2022-10-12 0.5% Santa Cruz Wharf
• 2022-10-17 0.5% Humboldt Bay, Indian Is. Ch.
• 2022-10-18 0.5% Mendocino, Noyo Harbor
• 2022-10-18 0.5% Pismo Pier
• 2022-10-18 0.5% Cayucos Pier
• 2022-10-20 0.5% Imperial Beach Pier
• 2022-10-21 0.5% San Simeon Pier
• 2022-10-24 0.5% Drakes Bay, Chimney Rock LBS
• 2022-10-24 0.5% Tomales Bay, Lease #M430-15
• 2022-10-24 0.5% Humboldt Bay, Indian Is. Ch.