Harmful Algae最新文献

{"title":"Insights into the differential removal of various red tide organisms using modified clay: Influence of biocellular properties and mechanical interactions","authors":"Xiaomiao Zang ,&nbsp;Zhiming Yu ,&nbsp;Xiuxian Song ,&nbsp;Xihua Cao ,&nbsp;Kaiqin Jiang","doi":"10.1016/j.hal.2024.102695","DOIUrl":"10.1016/j.hal.2024.102695","url":null,"abstract":"<div><p>In recent years, red tides have increased worldwide in frequency, intensity, involving a higher number of causative species during the events. As the most commonly used method for control of red tides, modified clay (MC) was found to have differential ability to remove various red tide species. However, the underlying mechanisms have not yet been completely elucidated. In this study, the use of MC to remove three typical disaster-causing species, <em>Aureococcus anophagefferens, Prorocentrum donghaiense</em> and <em>Heterosigma akashiwo,</em> was investigated, and differential removal of these species was probed with insights into their biocellular properties and mechanical interactions. The results showed that removal efficiencies of the three species by MC decreased in the order <em>P. donghaiense</em> &gt; <em>A. anophagefferens</em> &gt; <em>H. akashiwo</em>, while the sedimentation rates decreased in the order <em>H. akashiwo</em> &gt; <em>P. donghaiense</em> &gt; <em>A. anophagefferens</em>. Analyses of the cell surface properties and redundancy analysis (RDA) revealed that the highest surface zeta potential of -5.32±0.39 mV made <em>P. donghaiense</em> the most easily removed species; the smallest cell size of 3.30±0.03 μm facilitated the removal of <em>A. anophagefferens</em>; and the highest hydrophobicity with a H₂O surface contact angle of 98.50±4.31° made the removal of <em>H. akashiwo</em> difficult. X-ray photoelectron spectroscopy (XPS) data indicated that the electronegativity of <em>P. donghaiense</em> was caused by carboxyl groups and phosphodiester groups, and the hydrophobicity of <em>H. akashiwo</em> was associated with a high C-(C, H) content on the cell surface. According to the extended Derjaguin, Landau, Verwey, and Overbeek (ex-DLVO) theory calculation, differences in the interaction energies between MC and the three red tide species effectively explained their different sedimentation rates. In addition, the degree of oxidative damage caused by MC to the three red tide species differed, which also affected the removal of red tide organisms.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102695"},"PeriodicalIF":5.5,"publicationDate":"2024-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141713685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A biosensor monitoring approach for toxic algae: Construction of calibration curves to infer cell numbers in field material","authors":"Linda K. Medlin ,&nbsp;María García-Portela ,&nbsp;Araceli E. Rossignoli ,&nbsp;Beatriz Reguera","doi":"10.1016/j.hal.2024.102697","DOIUrl":"10.1016/j.hal.2024.102697","url":null,"abstract":"<div><p>A variety of shellfish toxin-producing Harmful Algal Blooms (HABs) occur every year in coastal temperate waters worldwide. These toxic HABs may cause lengthy (months) harvesting bans of mussels and other suspension feeding bivalves exposed to their blooms. To safeguard public health and the shellfish industry, European Union regulations request periodic monitoring of potentially toxic microalgae in seawater and phycotoxins in live bivalve molluscs from shellfish production areas. Monitoring of other toxic microalgae, e.g., fish killers, is based solely on cell counts. Morphological identification and quantification of microalgal cells with light microscopy is time-consuming, requires a good expertise, and accurate identification to species level (e.g., <em>Pseudo-nitzschia</em> species) may require electron microscopy. Toxicity varies among morphologically similar species; there are toxic and non-toxic strains of the same species. Molecular techniques using ribosomal DNA sequences offer a possibility to identify and detect precisely the potentially toxic genus/species. In an earlier project (MIDTAL), specific probes against rRNA sequences of all HAB taxa, known at the time of the project, affecting shellfish areas worldwide were designed, and those affecting Europe were tested and calibrated against rRNA extracts of clonal cultures and field samples. Microarray technology was adopted to relate to cell numbers the fluorescence signal from the reaction of all target species probes spotted in the microarray slides with those present in a single sample extract. The EMERTOX project aimed to develop a more automatic “Lab on a chip” (LOC) technology, including a non- (cell) disruptive water concentration system and biosensors for HAB cells detection. Here, calibration curves are presented against toxic microalgae (cultures and field samples) causing endemic and emerging toxicity events in Galicia (NW Spain) and Portugal. Results here relating cell numbers to electrochemical signals will be used in an early warning biosensor for toxic algae.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102697"},"PeriodicalIF":5.5,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324001306/pdfft?md5=bdd29cb695ab6c2c93bb8cf76bdf6d75&pid=1-s2.0-S1568988324001306-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141630854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Ciliate Euplotes balteatus Exhibits Removal Capacity upon the Dinoflagellates Karenia mikimotoi and Prorocentrum shikokuense","authors":"Jing Li ,&nbsp;Haifeng Gu ,&nbsp;Vincent J. Lovko ,&nbsp;Chen Liang ,&nbsp;Xiaodong Li ,&nbsp;Xin Xu ,&nbsp;Linxuan Jia ,&nbsp;Miaohua Jiang ,&nbsp;Jinrong Wang ,&nbsp;Jianming Chen","doi":"10.1016/j.hal.2024.102685","DOIUrl":"10.1016/j.hal.2024.102685","url":null,"abstract":"<div><p>The significant threat posed by the ichthyotoxic dinoflagellate <em>Karenia mikimotoi</em> to coastal aquaculture, resulting in substantial economic losses, underscores the need for control and mitigation strategies. Bio-mitigation of algal blooms through grazers presents advantages in sustainability compared to methods relying on chemical or physical procedures. This study explored the inhibitory effect of nine <em>Euplotes</em> spp. (Alveolata, Ciliophora) isolates on simulated blooms, with <em>E. balteatus</em> W413 displaying removal capacity for <em>K. mikimotoi</em> and robust growth in co-cultivation. The unique size plasticity in W413 revealed an efficient predation strategy, as an increase in cellular size enables it to shift prey from bacteria to algal cells. The enlarged cell volume facilitates W413 to accommodate more algal cells, bestowing it with a high ingestion rate and removal capacity upon <em>K. mikimotoi</em>. Furthermore, W413 exhibited considerable inhibition towards co-occurring bloom species, specifically <em>Prorocentrum shikokuense</em> and <em>Karenia</em> spp., implying its potential to mitigate mixed-species blooms. The study enhances our understanding of the prey selectivity of <em>Euplotes</em> species and proposes <em>E. balteatus</em> as a potential bio-mitigation candidate for <em>K. mikimotoi</em> blooms, emphasizing the significance of micro-grazers in marine ecosystems.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102685"},"PeriodicalIF":5.5,"publicationDate":"2024-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141701280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular monitoring of Dinophysis species assemblage in mussel farms in the Northwestern Adriatic Sea","authors":"Giorgia Ravera ,&nbsp;Monica Cangini ,&nbsp;Samuela Capellacci ,&nbsp;Sonia Dall'Ara ,&nbsp;Giuseppe Prioli ,&nbsp;Mauro Marini ,&nbsp;Elena Manini ,&nbsp;Antonella Penna ,&nbsp;Silvia Casabianca","doi":"10.1016/j.hal.2024.102686","DOIUrl":"10.1016/j.hal.2024.102686","url":null,"abstract":"<div><p>Several <em>Dinophysis</em> species can produce potent lipophilic toxins that pose a risk to human health when contaminated seafood is consumed, especially filter-feeding bivalve mussels. In the mussel farms of the Northwestern Adriatic Sea, seawater and seafood are regularly monitored for the presence of <em>Dinophysis</em> species and their associated toxins, but the current methodological approaches, such as light microscopy determinations, require a long time to make results available to local authorities. A molecular qPCR-based assay can be used to quantify various toxic <em>Dinophysis</em> species in a shorter timeframe. However, this approach is not currently employed in official testing activities. In this study, field samples were collected monthly or bi-weekly over one year from various mussel farms along the Northwestern Adriatic coast. The abundance of <em>Dinophysis</em> species in the seawater was determined using both traditional microscopy and qPCR assays. In addition, the concentration of lipophilic toxins for DSP in mussel flesh was quantified using LC-MS/MS focusing on the okadaic acid group. <em>Dinophysis</em> spp. site-specific single cells were isolated and analysed by qPCR yielding a mean rDNA copy number per cell of 1.21 × 10⁴ ± 1.81 × 10³. The qPCR assay gave an efficiency of 98 % and detected up to 10 copies of the rDNA target gene. The qPCR and light microscopy determinations in environmental samples showed a significant positive correlation (Spearman r<em>_s</em> = 0.57, <em>p</em>-value &lt; 0.001) with a ratio of 2.24 between the two quantification methods, indicating that light microscopy estimates were generally 44.6 % lower than those obtained by the qPCR assay. The qPCR approach showed several advantages such as rapidity, sensitivity and efficiency over conventional microscopy analysis, showing its potential future role in phytoplankton monitoring under the Official Controls Regulations for shellfish.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102686"},"PeriodicalIF":5.5,"publicationDate":"2024-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141630853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Drivers and mechanisms of harmful algal blooms across hydrologic extremes in hypereutrophic grand lake st marys (Ohio)","authors":"Silvia E. Newell ,&nbsp;Jason C. Doll ,&nbsp;Morgan C. Jutte ,&nbsp;Joseph L. Davidson ,&nbsp;Mark J. McCarthy ,&nbsp;Stephen J. Jacquemin","doi":"10.1016/j.hal.2024.102684","DOIUrl":"10.1016/j.hal.2024.102684","url":null,"abstract":"<div><p>Grand Lake St. Marys (GLSM) is a large, shallow, hypereutrophic lake situated in an agricultural watershed with high-nutrient, non-point source runoff. The resulting harmful algal blooms (HABs) are typically dominated by <em>Planktothrix</em>, which can produce microcystin, a potent cyanobacterial toxin that has varied in concentration over the past decade. Some drivers of bloom biomass and toxicity in GLSM are described, but recent years (2019–2022) have exhibited anomalous combinations of winter ice cover and spring runoff, suggesting that additional factors contribute to variability in HAB severity and toxicity. 2020 and 2022 were typical water years, with normal tributary runoff volumes occurring primarily in late winter and spring after either little to no ice cover (2019–2020) or heavy/prolonged ice cover (2021–2022). However, 2021 exhibited prolonged winter ice and low winter/spring runoff. 2020 and 2022 were typical bloom years, with near monoculture, <em>Planktothrix</em>-dominated biomass (11 to 405 μg/L total chlorophyll) and high total concentrations of microcystins (&lt;0.3 to 65 μg/L). However, the first half of 2021 exhibited lower biomass (18 to 65 μg/L chlorophyll a) and toxin concentrations (0.4 to 2.0 μg/L). While biomass returned to bloom levels when external tributary loading increased, ammonium uptake and regeneration rates and microcystin concentrations remained low throughout 2021 (in contrast to other years). Overall, potential ammonium uptake rates strongly correlated with chlorophyll and microcystin concentrations (Bayesian R² = 0.59; 95% CI = 0.44 to 0.65). Phytoplankton diversity was higher in 2021 than other years, especially in spring/early summer, with increased dinoflagellates and diatoms in spring, followed by a mixed cyanobacterial assemblage in summer. These results suggest that lower external nutrient loads can drive immediate positive impacts on water quality, such as reduced HAB biomass and toxicity and higher phytoplankton diversity, even in hypereutrophic, shallow lakes.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102684"},"PeriodicalIF":5.5,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141703237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Defense against Paramecium predation via long filament morphology favors the survival of Raphidiopsis raciborskii populations","authors":"Zeshuang Wang ,&nbsp;Xiaoli Huang ,&nbsp;Yangyang Wu ,&nbsp;Xiang Hu ,&nbsp;Qihang Zhao ,&nbsp;Jun Zuo ,&nbsp;Peng Xiao ,&nbsp;Yao Cheng ,&nbsp;He Zhang ,&nbsp;Renhui Li","doi":"10.1016/j.hal.2024.102678","DOIUrl":"https://doi.org/10.1016/j.hal.2024.102678","url":null,"abstract":"<div><p><em>Raphidiopsis</em> blooms are notorious for cyanotoxin formation and strong invasiveness, threatening the stability of aquatic ecosystems and human health. The protozoa <em>Paramecium</em> can potentially serve as an organism for controlling <em>Raphidiopsis</em> blooms owing to its grazing effect. However, the grazing ability of <em>Paramecium</em> is largely determined by the size of the prey, and the population of <em>Raphidiopsis</em> consists of filaments of varying lengths and sizes. The selective grazing behavior of <em>Paramecium</em> toward short-length or small-sized filaments in the <em>Raphidiopsis</em> population, as opposed to long filaments, remains unclear. Therefore, in this study, we co-cultured the predator <em>Paramecium</em> sp. with different initial abundances and the prey <em>Raphidiopsis raciborskii</em> to explore this knowledge gap. Our results suggested that: (1) the population of <em>R. raciborskii</em> declined under the selective grazing effect of <em>Paramecium</em> sp. on short filaments, whereas <em>R. raciborskii</em> with long filaments survived; (2) the growth of <em>Paramecium</em> sp. feeding on the same abundance of <em>R. raciborskii</em> was reduced at higher initial abundances, whereas its carrying capacity exhibited an opposite trend; (3) under ingestion by <em>Paramecium</em> sp., the morphology of <em>R. raciborskii</em> developed in the direction of becoming larger, and higher initial abundances of <em>Paramecium</em> sp. intensified this process; (4) increasing initial abundance of <em>Paramecium</em> sp. aggravated the decline of <em>R. raciborskii</em> photosynthetic activity. Therefore, the grazing effect of <em>Paramecium</em> sp. on <em>R. raciborskii</em> mainly affects filaments of short length or small size. Collectively, these results clarify the inter-species interaction between the protozoa <em>Paramecium</em> and filamentous cyanobacteria <em>Raphidiopsis</em>, including population dynamics and morphological and physiological changes in the predator and prey. Such insights into the interactions between <em>Paramecium</em> and <em>R. raciborskii</em> may have implications for the biological control of blooms caused by filamentous cyanobacteria.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"137 ","pages":"Article 102678"},"PeriodicalIF":5.5,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141479625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring factors that affect microcystis abundance in the sacramento san joaquin delta","authors":"Ellen P Preece,&nbsp;Rosemary Hartman","doi":"10.1016/j.hal.2024.102682","DOIUrl":"https://doi.org/10.1016/j.hal.2024.102682","url":null,"abstract":"<div><p>Cyanobacteria harmful algal blooms (cHABs) are increasing in frequency, intensity and duration in estuaries worldwide. In the upper San Francisco Estuary, also known as the Sacramento San Joaquin Delta (Delta), cHABs have been a topic of concern over the past two decades. In response, managers are urgently working to understand the factors that drive cHABs and identify feasible management options to avert ecological and human health consequences. We used a six year data set to explore relationships between flow parameters, temperature, and <em>Microcystis</em> biovolume to determine the potential for managing large scale hydrodynamic conditions to address Delta cHABs. We also looked at the relationship between <em>Microcystis</em> biovolume and the low salinity zone to see if it could be used as a proxy for residence time, because residence time is positively related to cyanobacteria abundance. We found the low salinity zone is not a useful proxy for residence time in the area of the Delta that experiences the most severe cHABs. Our finding suggest that climatic conditions (i.e., temperature and water year type) have the greatest influence on <em>Microcystis</em> biovolume in the Delta, with higher biovolume during years with lower flow and higher temperatures. Further, there are interannual differences in <em>Microcystis</em> biovolume that cannot be fully explained by flow parameters or temperature, meaning other factors not included in our model may be involved. We conclude that management actions to increase flow may be ineffective at reducing <em>Microcystis</em> to desired levels if water temperatures remain high.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102682"},"PeriodicalIF":5.5,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324001161/pdfft?md5=ce627202afda36d08487e61f02b4c2f4&pid=1-s2.0-S1568988324001161-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141592782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Alleviation of H2O2 toxicity by extracellular catalases in the phycosphere of Microcystis aeruginosa","authors":"Yerim Park,&nbsp;Wonjae Kim,&nbsp;Yeji Cha,&nbsp;Minkyung Kim,&nbsp;Woojun Park","doi":"10.1016/j.hal.2024.102680","DOIUrl":"https://doi.org/10.1016/j.hal.2024.102680","url":null,"abstract":"<div><p>High levels of environmental H₂O₂ represent a threat to many freshwater bacterial species, including toxic-bloom-forming <em>Microcystis aeruginosa</em>, particularly under high-intensity light conditions. The highest extracellular catalase activity-possessing <em>Pseudoduganella aquatica</em> HC52 was chosen among 36 culturable symbiotic isolates from the phycosphere in freshly collected <em>M. aeruginosa</em> cells. A zymogram for catalase activity revealed the presence of only one extracellular catalase despite the four putative catalase genes (<em>katA1, katA2, katE</em>, and <em>srpA</em>) identified in the newly sequenced genome (∼6.8 Mb) of <em>P. aquatica</em> HC52. Analysis of secreted catalase using liquid chromatography–tandem mass spectrometry was identified as KatA1, which lacks a typical signal peptide, although the underlying mechanism for its secretion is unknown. The expression of secreted KatA1 appeared to be induced in the presence of H₂O₂. Proteomic analysis also confirmed the presence of KatA1 inside the outer membrane vesicles secreted by <em>P. aquatica</em> HC52 following exposure to H₂O₂. High light intensities (&gt; 100 µmol m⁻² s⁻¹) are known to kill catalase-less axenic <em>M. aeruginosa</em> cells<em>,</em> but the present study found that the presence of <em>P. aquatica</em> cells supported the growth of <em>M. aeruginosa</em>, while the extracellular catalases in supernatant or purified form also sustained the growth of <em>M. aeruginosa</em> under the same conditions. Our results suggest that the extracellular catalase secreted by <em>P. aquatica</em> HC52 enhances the tolerance of <em>M. aeruginosa</em> to H₂O₂, thus promoting the formation of <em>M. aeruginosa</em> blooms under high light intensities.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"137 ","pages":"Article 102680"},"PeriodicalIF":5.5,"publicationDate":"2024-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141479627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Risk assessment of toxic cyanobacterial blooms in recreational waters: A comparative study of monitoring methods","authors":"Quirijn J.F. Schürmann ,&nbsp;Petra M. Visser ,&nbsp;Susan Sollie ,&nbsp;W. Edwin A. Kardinaal ,&nbsp;Elisabeth J. Faassen ,&nbsp;Ridouan Lokmani ,&nbsp;Ron van der Oost ,&nbsp;Dedmer B. Van de Waal","doi":"10.1016/j.hal.2024.102683","DOIUrl":"https://doi.org/10.1016/j.hal.2024.102683","url":null,"abstract":"<div><p>Toxic cyanobacterial blooms impose a health risk to recreational users, and monitoring of cyanobacteria and associated toxins is required to assess this risk. Traditionally, monitoring for risk assessment is based on cyanobacterial biomass, which assumes that all cyanobacteria potentially produce toxins. While these methods may be cost effective, relatively fast, and more widely accessible, they often lead to an overestimation of the health risk induced by cyanotoxins. Monitoring methods that more directly target toxins, or toxin producing genes, may provide a better risk assessment, yet these methods may be more costly, usually take longer, or are not widely accessible. In this study, we compared six monitoring methods (fluorometry, microscopy, qPCR of 16S and <em>mcyE</em>, ELISA assays, and LC-MS/MS), of which the last three focussed on the most abundant cyanotoxin microcystins, across 11 lakes in the Netherlands during the bathing water season (May-October) of 2019. Results of all monitoring methods significantly correlated with LC-MS/MS obtained microcystin levels (the assumed ‘golden standard’), with stronger correlations for methods targeting microcystins (ELISA) and microcystin genes (<em>mcyE</em>). The estimated risk levels differed substantially between methods, with 78 % and 56 % of alert level exceedances in the total number of collected samples for fluorometry and microscopy-based methods, respectively, while this was only 16 % and 6 % when the risk assessment was based on ELISA and LC-MS/MS obtained toxin concentrations, respectively. Integrating our results with earlier findings confirmed a strong association between microcystin concentration and the biovolume of potential microcystin-producing genera. Moreover, using an extended database consisting of 4265 observations from 461 locations across the Netherlands in the bathing water seasons of 2015 – 2019, we showed a strong association between fluorescence and the biovolume of potentially toxin-producing genera. Our results indicate that a two-tiered approach may be an effective risk assessment strategy, with first a biomass-based method (fluorometry, biovolume) until the first alert level is exceeded, after which the risk level can be confirmed or adjusted based on follow-up toxin or toxin gene analyses.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102683"},"PeriodicalIF":5.5,"publicationDate":"2024-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324001173/pdfft?md5=f1931eb14b0af6a154485c5b69483519&pid=1-s2.0-S1568988324001173-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141592783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Insights into the nature of ichthyotoxins from the Chrysochromulina leadbeateri blooms in Northern Norwegian fjords","authors":"Xinhui Wang ,&nbsp;Mathias Fon ,&nbsp;Aaron J.C. Andersen ,&nbsp;Anita Solhaug ,&nbsp;Richard A. Ingebrigtsen ,&nbsp;Ingunn A. Samdal ,&nbsp;Silvio Uhlig ,&nbsp;Christopher O. Miles ,&nbsp;Bente Edvardsen ,&nbsp;Thomas O. Larsen","doi":"10.1016/j.hal.2024.102681","DOIUrl":"https://doi.org/10.1016/j.hal.2024.102681","url":null,"abstract":"<div><p>In May–June 2019, the microalga <em>Chrysochromulina leadbeateri</em> caused a massive fish-killing event in several fjords in Northern Norway, resulting in the largest direct impact ever on aquaculture in northern Europe due to toxic algae. Motivated by the fact that no algal toxins have previously been described from <em>C. leadbeateri</em>, we set out to investigate the chemical nature and toxicity of secondary metabolites in extracts of two strains (UIO 393, UIO 394) isolated from the 2019 bloom, as well as one older strain (UIO 035) isolated during a bloom in Northern Norway in 1991. Initial LC–DAD–MS/MS-based molecular networking analysis of the crude MeOH extracts of the cultivated strains showed that their profiles of small organic molecules, including a large number of known lipids, were very similar, suggesting that the same class of toxin(s) were likely the causative agents of the two harmful algal bloom (HAB) events. Next, bioassay-guided fractionation using the RTgill-W1 cell line and metabolomics analysis pointed to a major compound affording [M + H]⁺ ions at <em>m/z</em> 1399.8333 as a possible toxin, corresponding to a compound with the formula C₆₇H₁₂₇ClO₂₇. Moreover, our study unveiled a series of minor analogues exhibiting distinct patterns of chlorination and sulfation, together defining a new family of compounds, which we propose to name leadbeaterins. Remarkably, these suspected toxins were detected <em>in situ</em> in samples collected during the 2019 bloom close to Tromsø, thereby consistent with a role in fish kills. The elemental compositions of the putative <em>C. leadbeateri</em> ichthyotoxins strongly indicate them to be long linear polyhydroxylated polyketides, structurally similar to sterolysins reported from a number of dinoflagellates.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"137 ","pages":"Article 102681"},"PeriodicalIF":5.5,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141543655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}