Variability and profiles of lipophilic toxins in bivalves from Great Britain during five and a half years of monitoring: azaspiracids and yessotoxins

Seasonal dynamics of lipophilic marine algal toxins in water body and sediment environments of nearshore mariculture areas in northern China

Lipophilic marine algal toxins (LMATs) pose risks to mariculture industries and human health. This study investigated the seasonal variation of LMATs in water and sediment environments at nearshore mariculture sites in China, in order to facilitate the prevention of LMAT contamination. Eight LMATs, including okadaic acid (OA), dinophysistoxin-1 (DTX1), pectenotoxin-2 (PTX2), gymnodimine, 13-desmethyl spirolide C, yessotoxin, homo-yessotoxin, and azaspiracid-2 and two derivatives-PTX2 Seco Acid and 7-epi-PTX-2 Seco Acid-were identified across various environmental samples. OA, DTX1, and PTX2 were dominant in Sishili Bay and Rongcheng Nearshore Bays. The composition and concentration of LMATs showed significant seasonal variation in both water and sediments. The total LMAT concentrations (∑LMATs) ranged from 4.20 ng/L to 107.62 ng/L in surface and bottom seawater, 2.01 ng/L to 120.58 ng/L in sediment porewater (mean 27.42 ng/L), and 17.04-490.87 ng/kg in sediments (mean 198.62 ng/kg). In water, LMAT diversity was higher in spring and summer, whereas concentrations peaked in summer and declined in winter. Conversely, ∑LMATs in sediments and porewater displayed a reciprocal seasonal pattern, implying dynamic exchange at the sediment-porewater interface. These findings highlight the seasonal dynamics of LMATs in mariculture sites, providing essential data for evaluating contamination risks during breeding cycle.

Characteristics and potential human health risks of Paralytic Shellfish Toxins identified in eight species of bivalves from South Yellow Sea Mudflat

The consumption of bivalves contaminated with paralytic shellfish toxins (PSTs) poses a serious risk to human health. However, the presence of PSTs in bivalves from the South Yellow Sea Mudflat remains unclear. This study comprehensively examined the characteristics and potential health risks of PSTs in eight species of bivalves from the South Yellow Sea Mudflat across four seasons. Typical PSTs, including STX, dcNeoSTX, GTX1, GTX2, GTX3, and GTX4, were detected in white clams, clams, short-necked clams, blue mussels, razor clams, mussels, scallops, and oysters. Significant differences of PSTs concentrations among bivalves across different seasons were detected using Kruskal-Wallis tests (p < 0.05), with the highest PSTs concentrations found in mussels (20.46 μg/individual) during autumn. Furthermore, Pearson tests revealed significant positive correlations between PSTs concentrations and shell length, shell height, shell width, and soft tissue wet weight, indicating that larger bivalves contain higher PSTs levels. The highest dietary toxin intake (DTI) of PSTs across the four seasons was found in mussels (2.138 μgSTX eq. kg⁻¹ bw day⁻¹) during autumn. Notably, the exposure risk index (ERI) from bivalve consumption for male consumers was 1.23 ± 0.819, which was higher than that for female consumers (1.102 ± 0.735). The ERI of PSTs for children aged 2-7 and the elderly over 65 were 1.448 ± 0.957 and 1.316 ± 0.874, respectively, which were higher than those for other age groups, indicating that children and the elderly are more sensitive to PSTs. It is important to note that most ERIs of PSTs from total tissues were higher than 1 (potential risk), while ERIs of PSTs from non-digestive tissues were lower than 1, suggesting that potential health risks could be reduced by removing the digestive tissues of bivalves before consumption. This study provides valuable information for mitigating health risks associated with bivalve consumption.

Spatiotemporal distribution of lipophilic shellfish toxins in plankton and shellfish in the offshore regions of Shandong province, China

Lipophilic shellfish toxins (LSTs) threaten the ecosystem health and seafood safety. To comprehensively investigate the spatiotemporal distribution of common LSTs in phytoplankton, zooplankton and economic shellfish, three cruises were conducted in five typical offshore aquaculture regions of Shandong province, China, including Haizhou Bay, Jiaozhou Bay, Sanggou Bay, Sishili Bay and Laizhou Bay, in spring (March-April), summer (July-August) and autumn (November-December). This study revealed significant variability in the composition and content of LSTs in phytoplankton samples collected from different regions. Pectenotoxin-2 (PTX2), dinophysistoxin-1 (DTX1) and okadaic acid (OA) were mainly detected in the ranges of not detected (nd)-5045 pmol g-1 dry weight (dw), nd-159 pmol g-1 dw, and nd-154 pmol g-1 dw, respectively. In zooplankton, DTX1 and OA were the predominant components of LSTs, with the highest levels of ∑LSTs in spring ranging from nd to 406 pmol g-1 dw. Spearman's correlation analysis between LSTs and environmental factors indicated significant correlations for the contents of homo-yessotoxin (hYTX), gymnodimine-A (GYM-A), and spirolide-1 (SPX1) with these factors. Totally relatively low levels of LSTs with dominative DTX1 were detected in economic shellfish, which showed a low risk to seafood safety for human health.

Investigating the etiology of Haff disease: Optimization and validation of a sensitive LC-MS/MS method for palytoxins analysis in directly associated freshwater and marine food samples from Brazil

Haff disease typically develops after eating contaminated marine or freshwater species, especially fish. Despite still having an unknown etiology, recent reports have suggested its possible correlation with palytoxins. Therefore, the present work aimed to optimize and perform a validation of a sensitive method using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) for the analysis of palytoxin and some of its analogs, with the main purpose of investigating their presence in marine and freshwater food samples associated with Haff disease in Brazil. The method optimization was performed using a central composite rotatable design and fish samples fortified with the palytoxin standard. Then, the optimized method was validated for different food matrices, including freshwater and marine fish, mollusks, and crustaceans. The sample preparation involved a solid-liquid extraction using methanol and water, solid-phase extraction using Strata-X cartridges, and on-column palytoxin oxidation. The detection of the main oxidized fragments (amino and amide aldehydes) was achieved by LC-MS/MS with electrospray ionization in positive mode, using a C18 column, as well as acetonitrile and water as mobile phases, both acidified with 0.1 % of formic acid. After optimization and validation, the etiological investigation involved the analysis of 16 Brazilian Haff disease-related food samples (in natura and leftover meals) from 2022. The method was demonstrated to be appropriate for quantitative analysis of freshwater and marine species. So far, it has proven to be one of the most sensitive methods related to palytoxin detection (LOD 10 μg/kg), being able to work in a range that includes the provisional ingestion limit (30 μg/kg). Regarding the Haff disease-related samples analysis, there is a strong indication of palytoxin contamination since the amino aldehyde (common fragment for all palytoxins) was detected in 15 of the 16 samples. Selected results were confirmed using liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS).

Marine toxins in seafood: Recent updates on sample pretreatment and determination techniques

Marine toxins can lead to varying degrees of human poisoning, often resulting in fatal symptoms and causing significant economic losses in seafood-producing regions. To gain a deeper comprehension of the role of marine toxins in seafood and their impact on the environment, it is imperative to develop rapid, cost-effective, environmentally friendly, and efficient methods for sample pretreatment and determination to mitigate adverse impacts of marine toxins. This review presents a comprehensive overview of advancements made in sample pretreatment and determination techniques for marine toxins since 2017. The advantages and disadvantages of various technologies were critically examined. Additionally, the current challenges and future development strategies for the analysis of marine toxins are provided.

Yessotoxins in Mollusks of the Galician Coast from 2014 to 2022: Variability, Biotransformation, and Resistance to Alkaline Hydrolysis

The presence of yessotoxins (YTXs) was analyzed in 10,757 samples of Galician bivalves from 2014 to 2022. Only YTX and 45-OH YTX were found. YTX was detected in 31% of the samples, while 45-OH YTX was found in 11.6% of them. Among the samples containing YTX, 45-OH YTX was detected in 37.3% of cases. The maximum recorded levels were 1.4 and 0.16 mg of YTX-equivalentsg-1, for YTX and 45-OH YTX, respectively, which are well below the regulatory limit of the European Union. The YTX and 45-OH YTX toxicities in the raw extracts and extracts subjected to alkaline hydrolysis were strongly and linearly related. Due to the lack of homo-YTX in Galician samples, the effect of alkaline hydrolysis on homo-YTX and 45OH-Homo-YTX was only checked in 23 additional samples, observing no negative effect but a high correlation between raw and hydrolyzed extracts. Hydrolyzed samples can be used instead of raw ones to carry out YTXs determinations in monitoring systems, which may increase the efficiency of those systems where okadaic acid episodes are very frequent and therefore a higher number of hydrolyzed samples are routinely analyzed. The presence of YTX in the studied bivalves varied with the species, with mussels and cockles having the highest percentages of YTX-detected samples. The presence of 45-OH YTX was clearly related to YTX and was detected only in mussels and cockles. Wild populations of mussels contained proportionally more 45-OH YTX than those that were raft-cultured. Spatially, toxin toxicities varied across the sampling area, with higher levels in raft-cultured mussels except those of Ría de Arousa. Ría de Ares (ARE) was the most affected geographical area, although in other northern locations, lower toxin levels were detected. Seasonally, YTX and 45-OH YTX toxicities showed similar patterns, with higher levels in late summer and autumn but lower toxicities of the 45-OH toxin in August. The relationship between the two toxins also varied seasonally, in general with a minimum proportion of 45-OH YTX in July-August but with different maximum levels for raft-cultured and wild mussel populations. Interannually, the average toxicities of YTX decreased from 2014 to 2017 and newly increased from 2018 to 2021, but decreased slightly in 2022. The relationship between 45-OH YTX and YTX also varied over the years, but neither a clear trend nor a similar trend for wild and raft mussels was observed.

Occurrence and phase distribution of lipophilic marine algal toxins in the bottom boundary layer and sediment-porewater system of two mariculture sites

To date, understanding the fate of lipophilic marine algal toxins (LMATs) in benthic environments on which cultivated shellfish depend is still limited. In this work, the occurrence, concentration levels, and phase distributions of LMATs in the benthic environments of two mariculture sites (Sishili and Rongcheng Bays) in China were investigated for the first time. Five LMATs: okadaic acid (OA), pectenotoxin-2 (PTX2), gymnodimine, 13-desmethyl spirolide C, and azaspiracid-2 (AZA2) and three derivatives: dinophysistoxin-1 isomer (DTX1-iso), pectenotoxin-2 seco acid, and 7-epi- pectenotoxin-2 seco acid were detected in different environmental samples. OA and PTX2 were the dominant LMATs in the bottom boundary layer (BBL) and sediment, whereas AZA2 was present in the sediment only. Notably, DTX1-iso was found for the first time to be widely distributed in the benthic environments of the bays. In BBL, the average proportion of LMATs in the dissolved phase (99.20%) was much higher than in the particulate phase (0.80%). Partition of LMATs was more balanced between sediment porewater (57.80% average proportion) and sediment (42.20%). The concentrations of ∑LMATs in the BBL seawater ranged from 19.09 ng/L to 41.57 ng/L (mean of 32.67 ng/L), and the spatial distribution trend was higher in offshore than nearshore. ∑LMATs concentrations in the sediment and porewater of the two bays ranged from 17.04 ng/kg to 150.13 ng/kg (mean of 53.58 ng/kg) and from 8.29 ng/L to 120.58 ng/L (mean of 46.63 ng/L), respectively. Their spatial distributions differed from those in BBL, showing a trend of high concentrations in areas with heavy land-based inputs. ∑LMATs concentrations in porewater were significantly higher than those in BBL seawaters, suggesting that the potential hazards of LMATs to benthic organisms may be underestimated.

Immediate and delayed effects of a heatwave and Prorocentrum lima ((Ehrenberg) Stein 1878) bloom on the toxin accumulation, physiology, and survival of the oyster Magallana gigas (Thunberg, 1793)

Warming could facilitate the intensification of toxic algal blooms, two important stressors for marine organisms that are predicted to co-occur more frequently in the future. We investigated the immediate and delayed effects of a heatwave and a simulated bloom (3 × 106 cells L-1) of the diarrhetic shellfish toxin (DST)-producing benthic dinoflagellate Prorocentrum lima on the survival, physiology (oxygen consumption rate, condition index, immune parameters), and toxin accumulation in the Pacific rock oyster Magallana (Crassostrea) gigas. Oysters exposed to both stressors contained higher mean DST concentrations (mean ± 1 SE: 173.3 ± 19.78 μg kg-1 soft tissue) than those exposed to P. lima bloom alone (120.4 ± 20.90 μg kg-1) and exceeded the maximum permitted levels for human consumption. Exposure to individual stressors and their combination modified the physiology of M. gigas. Oysters exposed to heatwave alone had significantly higher oxygen consumption rates (0.7 ± 0.06 mg O2 h-1 g-1) than the control (0.3 ± 0.06 mg O2 h-1 g-1). However, this was not observed in oysters exposed to both heatwave and P. lima (0.5 ± 0.06 mg O2 h-1 g-1). This alteration of the metabolic response to warming in the presence of P. lima may affect the ability of rock oysters to adapt to environmental stressors (i.e., a heatwave) to ensure survival. Immunomodulation, through changes in total hemocyte count, was observed in oysters exposed to P. lima alone and in combination with warming. Individual stressors and their combination did not influence the condition index, but one mortality was recorded in oysters exposed to both stressors. The findings of this study highlight the vulnerability of rock oysters to the predicted increased frequency of heatwaves and toxic algal blooms, and the increased likelihood of shellfish containing higher than regulatory levels of DST in warming coasts.

Occurrence and distribution of lipophilic marine algal toxins in the coastal seawater of Southeast China and the South China Sea

The composition, levels, and spatial distribution of dissolved lipophilic marine algal toxins (LMATs) including cyclic imines (CIs), yessotoxins (YTXs), okadaic acid (OA) and its derivatives, pectenotoxins (PTXs), azaspiracids (AZAs), and brevetoxins (BTXs) in the coastal waters of Southeast China (Xiamen) and the South China Sea (Hainan Island and Beibu Gulf) were investigated and compared for the first time. Dissolved AZA3 was firstly detected in the coastal seawater of China. OA and PTX2 were widely distributed in the three areas studied. Gymnodimine (GYM), 13-desmethyl spirolide C (SPX1), YTX, and homo-yessotoxins (h-YTX) were found mainly in the South China Sea. The average ∑LMAT concentrations in the coastal waters of Xiamen, Hainan Island, and Beibu Gulf were 10.02 ng/L, 4.21 ng/L, and 44.27 ng/L, respectively. More groups and much higher concentrations of LMATs occurred in the South China Sea than that in the other sea areas of China.

Marine Biotoxins in Whole and Processed Scallops from the Argentine Sea

Harmful algal blooms are an increasing worldwide threat to the seafood industry and human health as a consequence of the natural production of biotoxins that can accumulate in shellfish. In the Argentine Sea, this has been identified as an issue for the offshore fisheries of Patagonian scallops (Zygochlamys patagonica), leading to potentially harmful effects on consumers. Here we assess spatial and temporal patterns in marine biotoxin concentrations in Patagonian scallops harvested in Argentinian waters between 2012-2017, based on analyses for paralytic shellfish toxins, lipophilic toxins, and amnesic shellfish toxins. There was no evidence for concentrations of lipophilic or amnesic toxins above regulatory acceptance thresholds, with trace concentrations of pectenotoxin 2, azaspiracid 2 and okadaic acid group toxins confirmed. Conversely, paralytic shellfish toxins were quantified in some scallops. Gonyautoxins 1 and 2 dominated the unusual toxin profiles (91%) in terms of saxitoxin equivalents with maximum concentrations reaching 3985 µg STX eq/kg and with changes in profiles linked in part to seasonal changes. Total toxin concentrations were compared between samples of the adductor muscle and whole tissue, with results showing the absence of toxins in the adductor muscle confirming toxin accumulation in the digestive tracts of the scallops and the absence of a human health threat following the processing of scallop adductor meat. These findings highlight that paralytic shellfish toxins with an unusual toxin profile can occur in relatively high concentrations in whole Patagonian scallops in specific regions and during particular time periods, also showing that the processing of scallops on board factory ships to obtain frozen adductor muscle is an effective management process that minimizes the risk of poisonings from final products destined for human consumption.

Emerging Marine Biotoxins in European Waters: Potential Risks and Analytical Challenges

Harmful algal blooms pose a challenge regarding food safety due to their erratic nature and forming circumstances which are yet to be disclosed. The best strategy to protect human consumers is through legislation and monitoring strategies. Global warming and anthropological intervention aided the migration and establishment of emerging toxin producers into Europe's temperate waters, creating a new threat to human public health. The lack of information, standards, and reference materials delay effective solutions, being a matter of urgent resolution. In this work, the recent findings of the presence of emerging azaspiracids, spirolildes, pinnatoxins, gymnodimines, palitoxins, ciguatoxins, brevetoxins, and tetrodotoxins on European Coasts are addressed. The information concerning emerging toxins such as new matrices, locations, and toxicity assays is paramount to set the risk assessment guidelines, regulatory levels, and analytical methodology that would protect the consumers.

Variability and profiles of lipophilic marine toxins in shellfish from southeastern China in 2017-2020

A total of 1338 samples were analyzed by ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to study the toxin profiles of lipophilic marine toxins in bivalve mollusks collected from the southeast coast of China from 2017 to 2020. The most abundant toxin was HomoYTX, followed progressively by YTX and PTX2. Low proportions of OA, DTX-1, and DTX-2 were found. No AZA1, AZA2, and AZA3 were quantified above limit of quantitation (LOQ). The highest concentrations of HomoYTX, YTX, PTX2, OA, DTX-1, and DTX-2 were 429, 98.0, 40.3, 33.0, 22.6, and 26.5 μg/kg, respectively. Mussels (Mytilus galloprovincialis, Perna viridis), scallop (Chlamys farreri) and clam (Atrina pectinate) accumulated higher toxin levels than clams (Sinonovaculla Constricta, Ruditapes philippinarum), oyster (Crassostrea gigas) and scallop (Arca granosa). Homo YTX and PTX2 levels reached the maximum in July and June, respectively, and the OA-group peaked in August. The results provide a reliable basis for monitoring marine toxins and protecting the health of aquatic consumers.

Spatial distribution and source of biotoxins in phytoplankton from the South China Sea, China

Marine phycotoxins severely threaten ecosystem health and mariculture. This study investigates the spatial distribution and source of diverse phycotoxins in the South China Sea (SCS), during four 2019/2020 cruises. Saxitoxin (STX) and okadaic acid (OA) -groups, azaspiracids, cyclic imines, pectenotoxins (PTX), yessotoxins, and domoic acid (DA) toxins were analyzed in microalgal samples. PTX2 occurred with the highest (93.5%) detection rate (DR) during all cruises, especially in the Pearl River Estuary (PRE) in June 2019. Homo-yessotoxin (hYTX) and DA were found during three cruises in August 2020, and high DR of hYTX (67.7%, 29.3%) and DA (29.0%, 29.3%) in the PRE and Guangdong coast, respectively, in June 2019 and 2020, peaking at concentrations of 777 pg hYTX L^-1 and 38514 pg DA L^-1. The phycotoxin distribution demonstrated that DA-producing microalgae gathered close to the PRE and Guangdong coast, while hYTX-producing microalgae distributed relatively far offshore. Microalgae producing PTX2- and STX-group toxins were more widely living in the SCS. High-throughput sequencing results suggested that Alexandrium pacificum and Gonyaulax spinifera were responsible for STX-group toxins and hYTX, respectively, while Pseudo-nitzschia cuspidata was the main source of DA. Widely distributed PTX2, hYTX, and DA were reported for the first time in the SCS.

Method performance verification for the combined detection and quantitation of the marine neurotoxins cyclic imines and brevetoxin shellfish metabolites in mussels (Mytilus edulis) and oysters (Crassostrea gigas) by UHPLC-MS/MS

A single laboratory method performance verification is reported for a rapid sensitive UHPLC-MS/MS method for the quantification of eight cyclic imine and two brevetoxin analogues in two bivalve shellfish matrices: mussel (Mytilus edulis) and Pacific oyster (Crassostrea gigas). Targeted cyclic imine analogues were from the spirolide, gymnodimine and pinnatoxin groups, namely 20-Me-SPX-C, 13-desMe-SPX-C, 13,19-didesMe-SPX-C, GYM-A, 12-Me-GYM, PnTx-E, PnTx-F and PnTx-G. Brevetoxin analogues consisted of the shellfish metabolites BTX-B5 and S-desoxy-BTX-B2. A rapid dispersive extraction was used as well as a fast six-minute UHPLC-MS/MS analysis. Mobile phase prepared using ammonium fluoride and methanol was optimised for both chromatographic separation and MS/MS response to suit all analytes. Method performance verification checks for both matrices were carried out. Matrix influence was acceptable for the majority of analogues with the MS response for all analogues being linear across an appropriate range of concentrations. In terms of limits of detection and quantitation the method was shown to be highly sensitive when compared with other methods. Acceptable recoveries were found with most analogues, with laboratory precision in terms of intra- and inter-batch precision deemed appropriate. The method was applied to environmental shellfish samples with results showing low concentrations of cyclic imines to be present. The method is fast and highly sensitive for the detection and quantification of all targeted analogues, in both mussel and oyster matrices. Consequently, the method has been shown to provide a useful tool for simultaneous monitoring for the presence or future emergence of these two toxin groups in shellfish.

Lipophilic Toxins in Wild Bivalves from the Southern Gulf of California, Mexico

Most of the shellfish fisheries of Mexico occur in the Gulf of California. In this region, known for its high primary productivity, blooms of diatoms and dinoflagellates are common, occurring mainly during upwelling events. Dinoflagellates that produce lipophilic toxins are present, where some outbreaks related to okadaic acid and dinophisystoxins have been recorded. From January 2015 to November 2017 samples of three species of wild bivalve mollusks were collected monthly in five sites in the southern region of Bahía de La Paz. Pooled tissue extracts were analyzed using LC-MS/MS to detect lipophilic toxins. Eighteen analogs of seven toxin groups, including cyclic imines were identified, fortunately individual toxins did not exceed regulatory levels and also the total toxin concentration for each bivalve species was lower than the maximum permitted level for human consumption. Interspecific differences in toxin number and concentration were observed in three species of bivalves even when the samples were collected at the same site. Okadaic acid was detected in low concentrations, while yessotoxins and gymnodimines had the highest concentrations in bivalve tissues. Although in low quantities, the presence of cyclic imines and other lipophilic toxins in bivalves from the southern Gulf of California was constant.

Diversity and regional distribution of harmful algal events along the Atlantic margin of Europe

The IOC-ICES-PICES Harmful Algal Event Database (HAEDAT) was used to describe the diversity and spatiotemporal distribution of harmful algal events along the Atlantic margin of Europe from 1987 - 2018. The majority of events recorded are caused by Diarrhetic Shellfish Toxins (DSTs). These events are recorded annually over a wide geographic area from southern Spain to northern Scotland and Iceland, and are responsible for annual closures of many shellfish harvesting areas. The dominant causative dinoflagellates, members of the morphospecies 'Dinophysis acuminata complex' and D. acuta, are common in the waters of the majority of countries affected. There are regional differences in the causative species associated with PST events; the coasts of Spain and Portugal with the dinoflagellates Alexandrium minutum and Gymnodinium catenatum, north west France/south west England/south Ireland with A. minutum, and Scotland/Faroe Islands/Iceland with A. catenella. This can influence the duration and spatial scale of PST events as well as the toxicity of shellfish. The diatom Pseudo-nitzschia australis is the most widespread Domoic Acid (DA) producer, with records coming from Spain, Portugal, France, Ireland and the UK. Amnesic Shellfish Toxins (ASTs) have caused prolonged closures for the scallop fishing industry due to the slow depuration rate of DA. Amendments to EU shellfish hygiene regulations introduced between 2002 and 2005 facilitated end-product testing and sale of adductor muscle. This reduced the impact of ASTs on the scallop fishing industry and thus the number of recorded HAEDAT events. Azaspiracids (AZAs) are the most recent toxin group responsible for events to be characterised in the ICES area. Events associated with AZAs have a discrete distribution with the majority recorded along the west coast of Ireland. Ciguatera Poisoning (CP) has been an emerging issue in the Canary Islands and Madeira since 2004. The majority of aquaculture and wild fish mortality events are associated with blooms of the dinoflagellate Karenia mikimotoi and raphidophyte Heterosigma akashiwo. Such fish killing events occur infrequently yet can cause significant mortalities. Interannual variability was observed in the annual number of HAEDAT areas with events associated with individual shellfish toxin groups. HABs represent a continued risk for the aquaculture industry along the Atlantic margin of Europe and should be accounted for when considering expansion of the industry or operational shifts to offshore areas.

Multiple New Strains of Amphidomataceae (Dinophyceae) from the North Atlantic Revealed a High Toxin Profile Variability of Azadinium spinosum and a New Non-Toxigenic Az. cf. spinosum

Azaspiracids (AZA) are a group of lipophilic toxins, which are produced by a few species of the marine nanoplanktonic dinoflagellates Azadinium and Amphidoma (Amphidomataceae). A survey was conducted in 2018 to increase knowledge on the diversity and distribution of amphidomatacean species and their toxins in Irish and North Sea waters (North Atlantic). We here present a detailed morphological, phylogenetic, and toxinological characterization of 82 new strains representing the potential AZA producers Azadinium spinosum and Amphidoma languida. A total of ten new strains of Am. languida were obtained from the North Sea, and all conformed in terms of morphology and toxin profile (AZA-38 and-39) with previous records from the area. Within 72 strains assigned to Az. spinosum there were strains of two distinct ribotypes (A and B) which consistently differed in their toxin profile (dominated by AZA-1 and -2 in ribotype A, and by AZA-11 and -51 in ribotype B strains). Five strains conformed in morphology with Az. spinosum, but no AZA could be detected in these strains. Moreover, they revealed significant nucleotide differences compared to known Az. spinosum sequences and clustered apart from all other Az. spinosum strains within the phylogenetic tree, and therefore were provisionally designated as Az. cf. spinosum. These Az. cf. spinosum strains without detectable AZA were shown not to cause amplification in the species-specific qPCR assay developed to detect and quantify Az. spinosum. As shown here for the first time, AZA profiles differed between strains of Az. spinosum ribotype A in the presence/absence of AZA-1, AZA-2, and/or AZA-33, with the majority of strains having all three AZA congeners, and others having only AZA-1, AZA-1 and AZA-2, or AZA-1 and AZA-33. In contrast, no AZA profile variability was observed in ribotype B strains. Multiple AZA analyses of a period of up to 18 months showed that toxin profiles (including absence of AZA for Az. cf. spinosum strains) were consistent and stable over time. Total AZA cell quotas were highly variable both among and within strains, with quotas ranging from 0.1 to 63 fg AZA cell-1. Cell quota variability of single AZA compounds for Az. spinosum strains could be as high as 330-fold, but the underlying causes for the extraordinary large variability of AZA cell quota is poorly understood.

Marine natural products

This review covers the literature published in 2019 for marine natural products (MNPs), with 719 citations (701 for the period January to December 2019) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1490 in 440 papers for 2019), together with the relevant biological activities, source organisms and country of origin. Pertinent reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. Methods used to study marine fungi and their chemical diversity have also been discussed.

Temporal and spatial distribution of Azadinium species in the inland and coastal waters of the Pacific northwest in 2014-2018

Azaspiracids, produced by some species of the dinoflagellate genera Azadinium and Amphidoma, can cause a syndrome in humans called azaspiracid shellfish poisoning (AZP). In 1995, mussels from the Irish west coast contaminated with azaspiracids were, for the first time, linked to this human illness that has symptoms of nausea, vomiting, severe diarrhea, and stomach cramps. The only confirmed cases of AZP to date in the United States occurred in Washington State in 2008 from mussels imported from Ireland. Shortly after this case, several others involving similar gastrointestinal symptoms were reported by shellfish consumers from Washington State. However, no detectable diarrhetic shellfish toxins or Vibrio contamination were found. Cursory analysis of Solid Phase Adsorption Toxin Tracking (SPATT) samplers suggested the presence of azaspiracids in Washington State waters and motivated a study to evaluate the presence and distribution of Azadinium species in the region. During the spring and summer months of 2014-2015, quantitative polymerase chain reaction (qPCR) analyses detected the presence of the toxigenic species Azadinium poporum and A. spinosum on the outer coast and throughout the inland waters of Washington State. In 2016-2018, standard curves developed using A. poporum isolated from Puget Sound and A. spinosum isolated from the North Sea were used to quantify abundances of up to 10,525 cells L^-1 of A. poporum and 156 cells L^-1 of A. spinosum at shore-based sites. Abundances up to 1,206 cells L^-1 of A. poporum and 30 cells L^-1 of A. spinosum were measured in the coastal waters of the Pacific Northwest in 2017. Other harmful genera, including Alexandrium, Dinophysis, and Pseudo-nitzschia, were observed using light microscopy at coastal sites where A. poporum was also observed. In some samples where both A. poporum and A. spinosum were absent, an Amphidomataceae-specific qPCR assay indicated that other species of Azadinium or Amphidoma were present. The identification of Azadinium species in the PNW demonstrates the need to assess their toxicity and to incorporate their routine detection in monitoring programs to aid resource managers in mitigating risks to azaspiracid shellfish poisoning in this region.

The Application of Nanopore Sequencing Technology to the Study of Dinoflagellates: A Proof of Concept Study for Rapid Sequence-Based Discrimination of Potentially Harmful Algae

Harmful algal blooms (HABs) are a naturally occurring global phenomena that have the potential to impact fisheries, leisure and ecosystems, as well as posing a significant hazard to animal and human health. There is significant interest in the development and application of methodologies to study all aspects of the causative organisms and toxins associated with these events. This paper reports the first application of nanopore sequencing technology for the detection of eukaryotic harmful algal bloom organisms. The MinION sequencing platform from Oxford Nanopore technologies provides long read sequencing capabilities in a compact, low cost, and portable format. In this study we used the MinION to sequence long-range PCR amplicons from multiple dinoflagellate species with a focus on the genus Alexandrium. Primers applicable to a wide range of dinoflagellates were selected, meaning that although the study was primarily focused on Alexandrium the applicability to three additional genera of toxic algae, namely; Gonyaulax, Prorocentrum, and Lingulodinium was also demonstrated. The amplicon generated here spanned approximately 3 kb of the rDNA cassette, including most of the 18S, the complete ITS1, 5.8S, ITS2 and regions D1 and D2 of the 28S. The inclusion of barcode genes as well as highly conserved regions resulted in identification of organisms to the species level. The analysis of reference cultures resulted in over 99% of all sequences being attributed to the correct species with an average identity above 95% from a reference list of over 200 species (see Supplementary Material 1). The use of mock community analysis within environmental samples highlighted that complex matrices did not prevent the ability to distinguish between phylogenetically similar species. Successful identification of causative organisms in environmental samples during natural toxic events further highlighted the potential of the assay. This study proves the suitability of nanopore sequencing technology for taxonomic identification of harmful algal bloom organisms and acquisition of data relevant to the World Health Organisations "one health" approach to marine monitoring.