Pacic Northwest HAB risk key: Harmful Algal Blooms Bulletin = low = medium Apr 11, 2021 HAB risk = = high The statements, ndings, conclusions, and recommendations do not necessarily reect the views of NOAA or the Department of Commerce. Beach Sampling WA Pseudo-nitzschia & Domoic Acid OR Pseudo-nitzschia & Domoic Acid (Pseudo-nitzschia) (particulate domoic acid) Offshore Sampling (Pseudo-nitzschia) (particulate domoic acid) Pseudo-nitzschia (PN) abundances are quantified for large and small cell morphologies using light microscopy. Threshold values: 50,000 cells/L for large PN; 1,000,000 cells/L for small PN; which trigger additional testing for seawater particulate domoic acid (pDA). Seawater pDA values >200 ng/L lead to toxin accumulation in shellfish such as razor clams. Sampling sites, colored by relative PN abundance (high: > threshold value for either cell morphology; moderate: > 1/3 threshold; low: < 1/3 threshold) and pDA, are shown in the upper left two panels. “No data” indicates that there were no data within the previous 15 days. Time series of PN abundance (cells per liter = c/L) and pDA at select beaches are shown in the upper right main two panels. Offshore samples (lower left) are collected and analyzed at ~2 week intervals during late summer/early fall. Additional samples are collected by a remotely operated Environmental Sample Processor (ESP) that is moored off La Push, WA, in late spring and late summer. Decisions regarding shellfish harvest closures at individual beaches are made by the Washington Department of Health, the Oregon Department of Agriculture, and Coastal Treaty Tribes after measuring toxin levels in shellfish collected from each beach (WA link; OR link), and not from the information presented here. However, the information presented here aids coastal managershttp://tinyurl.com/qxku6f8 in betterhttp://tinyurl.com/hd5qq6x understanding and predicting the onset, duration, and magnitude of toxin outbreaks as well as their impacts. Pacific Ocean Indices Ocean Surface Currents Satellite Chlorophyll-a Summary - In late March coastal winds switched to predominantly upwelling-favorable. Since then ocean currents have been pushing a significant amount of riverine water south and offshore. During the past week, relatively cold bottom water (~8 °C) was observed on the shelf near Newport, OR, consistent with upwelling. The recent available satellite imagery shows elevated chlorophyll-a all along the coast north of Cape Blanco, OR, with highest concentrations near Research has shown that toxic HAB events off WA and OR tend to occur Newport, OR, and Grays Harbor, WA. So far, both during or following periods of El Niño and/or positive phases of the PDO, large and small morphologies of Pseudo-nitzschia when ocean temperatures are relatively warm. (PN) cells have been relatively sparse at all Cumulative Wind beaches. Highest concentrations were at Sunset and North-south Wind Stress Stress Seaside Beach, OR on 5-Apr (8,000 cells/L of large morphology cells) and at Kalaloch Beach, WA on 7-Apr (5,000 cells/L of small morphology cells). As a result of the relatively low PN cell abundanc- es, no seawater particulate domoic acid (pDA) samples have been analyzed. Offshore samples have also not been analyzed recently. Washington Southward wind stress drives coastal upwell- and Oregon razor clam DA concentrations continue Clouds often obstruct satellite views, to slowly decrease from highs obtained during the ing that can lead to plankton blooms. North- Primary currents flow north and south in but the extent of phytoplankton fall 2020 event. Samples from most WA beaches ward wind stress tends to push any existing winter and summer, respectively, except blooms can at times be seen from remain elevated over the 20-ppm threshold. The offshore plankton and toxins towards beaches. within ~10 km of shore, where fluctua- space. Blooms do not necessarily exception was Mocrocks, WA, where razor clam In addition, summer/fall toxic blooms often tions follow changes in wind direction. occur in years with a moderate cummulative reflect the presence of toxins. samples were ≤19 ppm as of 1-Apr. In OR, razor upwelling index (i.e. during years with clam DA was 19 ppm at Coos Bay North Jetty on fluctuating winds) rather than in years with LiveOcean Forecast Model 2-Apr, but samples collected at sites north of there sustained upwelling or downwelling winds. remain exceptionally high. Model Columbia River Discharge predicted sea Forecast - The current La Niña conditions are surface transitioning to an ENSO neutral state that is salinity with expected to persist through the summer months. particles The recent PDO value is negative. Coastal winds released near are presently upwelling-favorable and should the Juan de remain so all week. Additional plankton blooms, Fuca eddy and including PN, are likely during this time. The Heceta Bank extended forecast suggests the possibility of a and tracked switch to northward winds (downwelling-favor- The Columbia River plume can help transport HABs and three days into able) next Saturday, but that remains too far into toxins from the south, northward along the WA coast. the future. the future for certainty. For now, the expected However, the plume can also serve as a protective barrier southward and offshore ocean flows should keep by preventing offshore toxins from reaching beaches. beaches free of new marine toxins during the upcoming week. Thus, the risk of a toxic PN Marine Weather Forecast bloom appears low throughout the upcoming week, Mon Tues Wed Thur Mon - NE wind, 10 kt but we recommend consulting the LiveOcean Tues - NE wind, 10 kt forecasts near the week’s end as conditions may Wed - NE wind, 10 kt change. The current risk is with the lingering high Thur - NE wind, 10 kt concentrations of DA in shellfish from the fall 2020 event. Fair weather can support plankton blooms whereas storms can concentrate any plankton and toxins on beaches..