Monitoring Oregon Coastal Harmful Algae: Observations and implications of a harmful algal bloom-monitoring project

The accumulation of domoic acid (DA) and saxitoxins (STX), phycotoxins produced by some species of Pseudo-nitzschia and Alexandrium, respectively, in coastal food webs are a focus of research on the West Coast of the United States due to the deleterious effects they have on coastal ecosystems and economies. Results are presented from the 2007–2012 Monitoring Oregon Coastal Harmful Algae (MOCHA) project, the Oregon coast's first HAB monitoring and research program. Both historical toxin databases and more detailed case-study observations of individual HAB events are compiled to provide the first detailed overview of HAB occurrence in this region. These results are also presented in the context of informing future HAB monitoring in this and other upwelling regimes affected by STX and DA. A 2009–2010 warming event was associated with the greatest HAB activity during the MOCHA project, including anomalously high sea surface temperatures and shellfish harvesting closures due to STX and DA in 2009 and 2010, respectively. In regards to HAB monitoring, it is shown that (1) razor clams are a more sensitive indicator of DA than mussels; (2) water column concentrations of particulate domoic acid greater than 10³ng L⁻¹ can be used as a threshold for early-warning of shellfish DA toxicity and (3) approximately bi-weekly, or shorter, monitoring of Alexandrium in the surf zone and/or offshore can provide advance notice of STX contamination of shellfish. Both of the latter two metrics gain added value when coupled with local wind stress, a proxy of downwelling/relaxation events that facilitate greater interaction between offshore blooms and shellfish.Keywords: Oregon coast, Saxitoxin, Domoic acid, Alexandrium, Harmful algal bloom, Pseudo-nitzschi

Rapid Enzyme-linked Immunosorbent Assay for Detection of the Algal Toxin Domoic Acid

Domoic acid (DA) is a potent toxin produced by bloom-forming phytoplankton in the genus Pseudo-nitzschia, which is responsible for causing amnesic shellfish poisoning (ASP) in humans. ASP symptoms include vomiting, diarrhea, and in more severe cases confusion, loss of memory, disorientation, and even coma or death. This paper describes the development and validation of a rapid, sensitive, enzyme linked immunosorbent assay test kit for detecting DA using a monoclonal antibody. The assay gives equivalent results to those obtained using standard high performance liquid chromatography, fluorenylmethoxycarbonyl high performance liquid chromatography, or liquid chromatography—mass spectrometry methods. It has a linear range from 0.1–3 ppb and was used successfully to measure DA in razor clams, mussels, scallops, and phytoplankton. The assay requires approximately 1.5 h to complete and has a standard 96-well format where each strip of eight wells is removable and can be stored at 4°C until needed. The first two wells of each strip serve as an internal control eliminating the need to run a standard curve. This allows as few as 3 or as many as 36 duplicate samples to be run at a time enabling real-time sample processing and limiting degradation of DA, which can occur during storage. There was minimal cross-reactivity in this assay with glutamine, glutamic acid, kainic acid, epi- or iso-DA. This accurate, rapid, cost-effective, assay offers environmental managers and public health officials an effective tool for monitoring DA concentrations in environment samples

Monitoring Diarrhetic Shellfish Poisoning (DSP) in Washington

Monitoring for diarrhetic shellfish toxins (DSTs) was initiated in the summer of 2011 when the first illness due to diarrhetic shellfish poisoning (DSP) was reported in the state of Washington. Monitoring strategy includes collection of whole seawater for identification and enumeration of Dinophysis and several shellfish species collected from two sites in Sequim Bay, WA as well as other sites throughout Puget Sound during the following summer (2012). Shellfish samples were analyzed for Okadaic acid toxin group including DTX-1, DTX-2 and DTX-3 using rapid screening methods based on the functional assays, i.e. the protein phosphatase 2A inhibition assay (PP2A); the anti OA antibody in an enzyme-linked immunosorbent assay (ELISA) and a lateral flow test strip (Jellett Rapid Test) and the chemical method, i.e. liquid chromatography coupled with tandem mass spectroscopy (LC-MS/MS). The application of a rapid screening method along with Dinophysis cell counts can provide quick assessment of toxin levels, and the results of this study suggest that PP2A is better at screening for OA group of DSTs. The reason for this is due to the fact that DSTs in Washington consist mostly as DTX-1; test kits with antibody-based application tend to under-estimate toxin levels present because the antibody used in these tests is specific to Okadaic acid (100% cross-reactivity) and only 50% to DTX-1

Response to an Emerging Threat to Human Health: Diarrhetic Shellfish Poisoning in Washington State

The toxins associated with diarrhetic shellfish poisoning (DSP), produced by Dinophysis species and concentrated in shellfish by filter feeding, are now routinely monitored by the Washington State Department of Health (WDOH) since the confirmed human illnesses in 2011. The emergence of this new threat to public health had an immediate impact on the Jamestown S’Klallam Tribe whose subsistence and commercial shellfish beds are located near the site where the DSP events occurred from consumption of toxic mussels. In 2012, a collaborative research project was initiated together with the SoundToxins partnership, to determine whether routine monitoring Dinophysis abundance could provide an early warning of concentrations of DSTs accumulated by shellfish. Weekly sampling illustrated that dinophysistoxin-1 (DTX-1) was the primary responsible toxin isomer in WA and that mussels generally concentrated the toxin more than other shellfish. In addition, it was found that D. acuminata was the primary species present during toxic events and increases in cell density often predicted increases in shellfish toxicity. However, surface water samples analyzed from several sites in Discovery Bay did not show elevated numbers of Dinophysis cells as a precursor to DSTs in shellfish. In Sequim Bay, tidal cycle and water depth influenced the abundance of Dinophysis sampled over a 48 h period, demonstrating the need to optimize sampling protocols in order to successfully detect cells in an early warning mode

A collaborative response to emerging threats to human health in the Salish Sea: Diarrhetic Shellfish Poisoning (DSP) and Azaspiracid Shellfish Poisoning (AZP)

The first confirmed DSP human illnesses in the United States occurred in 2011 due to the consumption of mussels from Sequim Bay State Park on Washington’s Olympic Peninsula. The emergence of this new threat to public health had an immediate impact on the Jamestown S’Klallam Tribe, whose shellfish beds were located nearby. In the four years since, the Tribe has collaborated with NOAA, the Washington State Department of Health (WDOH) and the volunteer-based SoundToxins partnership to help develop a management strategy for DSP. DSP has proved to be a persistent problem in Sequim Bay with shellfish above the regulatory limit for DSP toxins every year since the initial human cases. In addition, the causative organisms, dinoflagellates of the genus Dinophysis, are also quite common in the spring, summer and fall in Sequim Bay. This collaboration has, in the last few years been able to determine that DTX-1 is the most common DSP toxin in Puget Sound shellfish, the relative uptake rates of DSP toxins in several species of shellfish and how best to utilize SoundToxin’s observations of Dinophysis in the water column to prioritize shellfish samples for DSP testing at the WDOH laboratory. These partners have now turned their focus to the potentially toxic dinoflagellates in the genus Azadinium. Azadinium has been known produce azaspiracids in other parts of the world, toxins that can a cause a syndrome in humans called Azaspiracid Shellfish Poisoning (AZP) with symptoms similar to DSP. In a pilot study three species of these small dinoflagellates were found in Puget Sound using the molecular technique of qPCR (A. spinosum, A. obesum, and A. poporum). A new multi-year study will determine the distribution of Azadinium species in Puget Sound and whether they are producing azaspiracids

Screening Tests for the Rapid Detection of Diarrhetic Shellfish Toxins in Washington State

The illness of three people due to diarrhetic shellfish poisoning (DSP) following their ingestion of recreationally harvested mussels from Sequim Bay State Park in the summer of 2011, resulted in intensified monitoring for diarrhetic shellfish toxins (DSTs) in Washington State. Rapid testing at remote sites was proposed as a means to provide early warning of DST events in order to protect human health and allow growers to test “pre-harvest” shellfish samples, thereby preventing harvest of toxic product that would later be destroyed or recalled. Tissue homogenates from several shellfish species collected from two sites in Sequim Bay, WA in the summer 2012, as well as other sites throughout Puget Sound, were analyzed using three rapid screening methods: a lateral flow antibody-based test strip (Jellett Rapid Test), an enzyme-linked immunosorbent assay (ELISA) and a protein phosphatase 2A inhibition assay (PP2A). The results were compared to the standard regulatory method of liquid chromatography coupled with tandem mass spectroscopy (LC-MS/MS). The Jellett Rapid Test for DSP gave an unacceptable number of false negatives due to incomplete extraction of DSTs using the manufacturer’s recommended method while the ELISA antibody had low cross-reactivity with dinophysistoxin-1, the major toxin isomer in shellfish from the region. The PP2A test showed the greatest promise as a screening tool for Washington State shellfish harvesters

Screening Tests for the Rapid Detection of Diarrhetic Shellfish Toxins in Washington State

The illness of three people due to diarrhetic shellfish poisoning (DSP) following their ingestion of recreationally harvested mussels from Sequim Bay State Park in the summer of 2011, resulted in intensified monitoring for diarrhetic shellfish toxins (DSTs) in Washington State. Rapid testing at remote sites was proposed as a means to provide early warning of DST events in order to protect human health and allow growers to test “pre-harvest” shellfish samples, thereby preventing harvest of toxic product that would later be destroyed or recalled. Tissue homogenates from several shellfish species collected from two sites in Sequim Bay, WA in the summer 2012, as well as other sites throughout Puget Sound, were analyzed using three rapid screening methods: a lateral flow antibody-based test strip (Jellett Rapid Test), an enzyme-linked immunosorbent assay (ELISA) and a protein phosphatase 2A inhibition assay (PP2A). The results were compared to the standard regulatory method of liquid chromatography coupled with tandem mass spectroscopy (LC-MS/MS). The Jellett Rapid Test for DSP gave an unacceptable number of false negatives due to incomplete extraction of DSTs using the manufacturer’s recommended method while the ELISA antibody had low cross-reactivity with dinophysistoxin-1, the major toxin isomer in shellfish from the region. The PP2A test showed the greatest promise as a screening tool for Washington State shellfish harvesters

Diarrhetic Shellfish Toxins and Other Lipophilic Toxins of Human Health Concern in Washington State

Abstract: The illness of three people in 2011 after their ingestion of mussels collected from Sequim Bay State Park, Washington State, USA, demonstrated the need to monitor diarrhetic shellfish toxins (DSTs) in Washington State for the protection of human health. Following these cases of diarrhetic shellfish poisoning, monitoring for DSTs in Washington State became formalized in 2012, guided by routine monitoring of Dinophysis species by the SoundToxins program in Puget Sound and the Olympic Region Harmful Algal Bloom (ORHAB) partnership on the outer Washington State coast. Here we show that the DSTs at concentrations above the guidance level of 16 μg okadaic acid (OA) + dinophysistoxins (DTXs)/100 g shellfish tissue were widespread in sentinel mussels throughout Puget Sound in summer 2012 and included harvest closures of California mussel, varnish clam, manila clam and Pacific oyster. Concentrations of toxins in Pacific oyster and manila clam were often at least half those measured in blue mussels at the same site. The primary toxin isomer in shellfish and plankton samples was dinophysistoxin-1 (DTX-1) with D. acuminata as th

Monitoring Oregon Coastal Harmful Algae: Observations and implications of a harmful algal bloom-monitoring project

AbstractThe accumulation of domoic acid (DA) and saxitoxins (STX), phycotoxins produced by some species of Pseudo-nitzschia and Alexandrium, respectively, in coastal food webs are a focus of research on the West Coast of the United States due to the deleterious effects they have on coastal ecosystems and economies. Results are presented from the 2007–2012 Monitoring Oregon Coastal Harmful Algae (MOCHA) project, the Oregon coast's first HAB monitoring and research program. Both historical toxin databases and more detailed case-study observations of individual HAB events are compiled to provide the first detailed overview of HAB occurrence in this region. These results are also presented in the context of informing future HAB monitoring in this and other upwelling regimes affected by STX and DA. A 2009–2010 warming event was associated with the greatest HAB activity during the MOCHA project, including anomalously high sea surface temperatures and shellfish harvesting closures due to STX and DA in 2009 and 2010, respectively. In regards to HAB monitoring, it is shown that (1) razor clams are a more sensitive indicator of DA than mussels; (2) water column concentrations of particulate domoic acid greater than 103ngL−1 can be used as a threshold for early-warning of shellfish DA toxicity and (3) approximately bi-weekly, or shorter, monitoring of Alexandrium in the surf zone and/or offshore can provide advance notice of STX contamination of shellfish. Both of the latter two metrics gain added value when coupled with local wind stress, a proxy of downwelling/relaxation events that facilitate greater interaction between offshore blooms and shellfish