Harmful Algae最新文献

{"title":"Genetic diversity of Aureococcus anophagefferens in the coastal waters of China and implications for intraspecific differentiation of environmental adaptability","authors":"Chao Liu ,&nbsp;Qingchun Zhang ,&nbsp;Zhenfan Chen ,&nbsp;Lu Sun ,&nbsp;Fanzhou Kong ,&nbsp;Rencheng Yu","doi":"10.1016/j.hal.2025.102985","DOIUrl":"10.1016/j.hal.2025.102985","url":null,"abstract":"<div><div><em>Aureococcus anophagefferens</em>, a globally distributed picoplankton species, plays a critical role as a primary producer in marine ecosystems, and is responsible for brown tides in coastal waters, which significantly impact local environments and shellfisheries. Despite its pronounced adaptability across diverse marine habitats—from open oceans to estuaries—the genetic diversity underlying its niche differentiation remains poorly understood. This study investigated the intraspecific genetic diversity of <em>A. anophagefferens</em> in China’s coastal waters and the western Pacific, employing a novel mitochondrial marker (<em>trn</em>D-<em>dam</em>1) to resolve fine-scale population structure. Three distinct genotypes were identified, each exhibiting distinct environmental preferences: Type I dominated brown tide blooms in eutrophic, warm, low-salinity estuaries in the Bohai and Yellow Seas, correlating strongly with elevated dissolved organic nitrogen. In contrast, Types II (prevalent in U.S. strains) and III prevailed in high-salinity habitats, and associated with coastal zones influenced by transoceanic currents. Spatial-temporal analyses revealed genotype succession during bloom dynamics, with Type I constituting over 80 % of the population during peak bloom phases and coexisting with Type II during non-bloom periods. Samples from the Kuroshio Current exclusively harbored Types II and III, suggesting that oceanographic transport facilitates their dispersal. These findings indicate that <em>A. anophagefferens</em> populations have undergone adaptive divergence to exploit local environmental gradients, with genotype-specific preferences for temperature, salinity, and nutrient regimes shaping their biogeographic distribution.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102985"},"PeriodicalIF":4.5,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145155628","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":"Non-target effects of a harmful algal bloom biocontrol technology (DinoSHIELD) in an in-situ mesocosm experiment","authors":"Yanfei Wang ,&nbsp;William C. Holland ,&nbsp;Alexandria G. Hounshell ,&nbsp;Alan Kennedy ,&nbsp;Kaytee Pokrzywinski ,&nbsp;Kathryn J. Coyne","doi":"10.1016/j.hal.2025.102984","DOIUrl":"10.1016/j.hal.2025.102984","url":null,"abstract":"<div><div>Harmful algal blooms (HABs) of toxic dinoflagellates, including <em>Karenia brevis</em>, pose significant threats to marine organisms and human health worldwide. Previous research identified a naturally occurring algicidal bacterium, <em>Shewanella</em> sp. IRI-160, which secretes algicidal compounds that limit the growth of dinoflagellates. More recent research focused on the development of a HAB bio-control technology, now called DinoSHIELD, using alginate hydrogel to immobilize <em>Shewanella</em> sp. IRI-160. DinoSHIELD continuously releases bacteria-derived algicides that target dinoflagellate growth while limiting bacterial dispersion. In this study, an <em>in-situ</em> mesocosm experiment using natural microbial communities was conducted to assess the environmental impacts of DinoSHIELD. This study aimed to evaluate the effects of DinoSHIELD on water quality and on non-target microbial communities under non-HAB conditions. At an application rate effective at controlling the growth of <em>K. brevis</em> in laboratory cultures, DinoSHIELD had minimal effects on water quality within the mesocosms. There was no significant effect on overall photosynthetic biomass or the abundance of non-target microbial organisms during the 6-day mesocosm experiment. Although there was no significant change in microbial eukaryotic community structure, 18S rRNA gene sequencing analysis showed that DinoSHIELD significantly increased species richness in the treatment compared to controls. Importantly, analysis of total bacterial and <em>Shewanella</em> sp. IRI-160-specific cell densities showed limited release of bacteria from DinoSHIELD and no change in total bacterial densities. Overall, these results support the eventual use of DinoSHIELD as a biocontrol strategy for managing dinoflagellate HABs without negatively affecting natural microbial communities or the surrounding environment.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102984"},"PeriodicalIF":4.5,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217316","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":"Transcriptomic analysis of dinoflagellate Prorocentrum cordatum exposed to microplastics under different nitrogen sources","authors":"Heng Chen ,&nbsp;Qianlou Liu ,&nbsp;Sihao Yang ,&nbsp;Yiyi Cai ,&nbsp;Ziyu Song ,&nbsp;Yao Yang ,&nbsp;Rodrigo J. Gonçalves ,&nbsp;Wanchun Guan","doi":"10.1016/j.hal.2025.102983","DOIUrl":"10.1016/j.hal.2025.102983","url":null,"abstract":"<div><div>Anthropogenic activities have significantly altered marine nitrogen (N) regimes by releasing different forms of N (e.g. nitrate and urea, the latter from wastewater/agricultural runoff). Some species can grow equally well under different N sources, while others show maximum growth rates under one source (e.g. urea). Another pollutant, plastic microparticles (MP), has been found in every ecosystem/habitat on Earth. A crucial deleterious effect of MP is the disruption of the cellular membrane integrity—a key mechanism affecting the N uptake and assimilation in single-cell organisms such as dinoflagellates and microalgae. The combined effects of MP and different N sources remain an open question. This study exposed the dinoflagellate <em>Prorocentrum cordatum</em> to microplastics (MP, concentrations of 0 or 10 mg <em>L</em>⁻¹) with urea (U) or nitrate as nitrogen sources, both at 440 µmol <em>L</em>⁻¹ during 16 d to investigate the response of <em>P. cordatum</em> in terms of physiology and nitrogen metabolism. <em>P. cordatum</em> showed a similar growth rate, pigment contents (chlorophyll a and carotenoids), lipid peroxidation (MDA), nitrate reductase, and nitrogen consumption rate (<em>C</em>_N) in both N sources. The addition of MP under both nitrogen sources decreased growth but increased pigments, SOD and Urease activity, and MDA level, significanlty. The <em>C</em>_N was reduced by ∼50 % in the Microplastics + nitrate treatment (MPN), whereas it remained unchanged in the Microplastics + Urea treatment (MPU). At the transcriptomic level, the MP addition resulted in an approximate 2.5-fold increase in the number of differentially expressed genes (1811) under MPU compared to MPN (731). The MPU significantly upregulated pathways involving nitrogen assimilation and metabolism, endocytosis and phagosome, and further electron transport in photosynthesis and energy metabolism, but MPN downregulated those pathways. This suggests higher cellular metabolism under MPU compared to MPN. Additionally, cells in MPU upregulated pathways of antioxidation, heat shock protein, ubiquitin-mediated proteolysis, and proteasome in response to MP-induced stress, whereas the variations of these pathways in MPN were limited. These results shed light on the combined effects of urea as a source of nitrogen and MP exposure, providing insight into the metabolic flexibility of <em>P. cordatum</em> under future environmental stress.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102983"},"PeriodicalIF":4.5,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145155626","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":"The Guiana current: a fast-lane to the Caribbean for holopelagic Sargassum contaminated in arsenic and cadmium","authors":"Tristan Gobert ,&nbsp;Solène Connan ,&nbsp;Donald R. Johnson ,&nbsp;Matthieu Waeles","doi":"10.1016/j.hal.2025.102981","DOIUrl":"10.1016/j.hal.2025.102981","url":null,"abstract":"<div><div>To date, little key information about inorganic arsenic (iAs) and cadmium (Cd) has been promulgated to help manage the massive influxes of pelagic <em>Sargassum</em> that have inundated the Caribbean coasts since 2011 and are causing significant environmental, health and economic impacts. In particular, the levels of iAs and Cd, which often exceed regulatory levels and limit the seaweed valorization, have not been linked to an origin or route. By analyzing a large number of samples collected at different times in Guadeloupe and Martinique, we have highlighted for the first time a route that rapidly traces back through the Guiana, North-Brazil and equatorial currents, bringing <em>Sargassum</em> to the Lesser Antilles in &lt;3 months from the equator. All the <em>Sargassum</em> morphotypes from this problematic fast track displayed high levels of iAs and Cd, very often exceeding 40 ppm and 1 ppm, respectively. The other routes, which bring <em>Sargassum</em> more slowly, either from the Cape Verde basin or from the North Brazil Retroflection area, have low or intermediate levels of iAs and Cd. Following an in-depth examination of the cadmium-phosphorus relationship in the tropical Atlantic Ocean, we provide here for the first time an overview of the spatial disparities in the Cd and P composition of <em>Sargassum</em>.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102981"},"PeriodicalIF":4.5,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145109784","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":"Sargassum influxes in West Africa: Impacts, challenges, and prospects for sustainable management","authors":"Abdulwakil Olawale Saba ,&nbsp;Kafayat Adetoun Fakoya ,&nbsp;Lucette Adet ,&nbsp;Hussein Aliu Sule ,&nbsp;Akinloye Emmanuel Ojewole ,&nbsp;Nimah Folake Osho-Abdulgafar","doi":"10.1016/j.hal.2025.102982","DOIUrl":"10.1016/j.hal.2025.102982","url":null,"abstract":"<div><div>The causes and mechanisms behind the influx of <em>Sargassum</em> in West Africa are poorly understood. The lack of effective management and control measures negatively impacts fishing, tourism, and marine life, leaving coastal communities with insufficient adaptive strategies. Research on <em>Sargassum</em> in the region is limited, which may lead to an underestimation of the socio-economic impacts of the blooms. Regional efforts led by the Abidjan Convention Secretariat and the United Nations Environment Programme (UNEP) have yet to yield significant results. There are considerable gaps in funding, policy prioritization, capacity building, and access to technology for early detection and monitoring, all of which are essential for implementing an effective <em>Sargassum</em> management strategy. Between 2018 and 2023, estimates of stranded biomass across the tropical Atlantic ranged from 2 to 10 million tons annually, with West Africa contributing a smaller yet still significant share. The biochemical composition of West African <em>Sargassum</em> demonstrates some economic potential, though heavy metal contamination and monitoring challenges limit use, necessitating the need for targeted management and detoxification efforts. While <em>Sargassum</em> presents opportunities for innovation and sustainable economic use, resources for developing regional value chains are scarce. West Africa could benefit from a more deliberate collaborative transatlantic partnership, as well as from strengthening an integrated regional strategy to create scalable and sustainable solutions in research, policy, management, and practical applications.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102982"},"PeriodicalIF":4.5,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145106560","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":"Harmful algal bloom species identified in the East China Sea through metabarcoding analysis of large-scale sampling expedition","authors":"Yang Chen ,&nbsp;Shuya Liu ,&nbsp;Nansheng Chen","doi":"10.1016/j.hal.2025.102977","DOIUrl":"10.1016/j.hal.2025.102977","url":null,"abstract":"<div><div>East China Sea (ECS) is known for its frequent occurrences of harmful algal blooms (HABs) especially in spring, many of which are toxigenic. In this study, we identified HAB species through metabarcoding analysis of 178 water samples collected from 44 sampling sites at different depths in the continental shelf of ECS in spring of 2019. Through amplicon sequence variant (ASV)-based metabarcoding analysis, we identified 3896 ASVs representing 32 classes in six phytoplankton phyla/divisions, among which Dinoflagellata was the most dominant phylum. Among 244 phytoplankton species annotated in this study, 67 HAB species were identified, of which 29 species having the potential to produce toxin. Many of these identified HAB species displayed unique spatial distribution patterns. Phylogenetic network analysis revealed rich molecular diversity of <em>Prorocentrum, Alexandrium</em> and <em>Pseudo-nitzschia</em> genera. Temperature and NO₃^- both showed significant correlations with most phytoplankton phyla (<em>p</em> &lt; 0.01), while PO₄^3- exhibited significant correlations with the dominant HAB species <em>Chaetoceros tenuissimus</em> (<em>p</em> &lt; 0.05) and <em>Scrippsiella trochoidea</em> (<em>p</em> &lt; 0.01). Clearly, these environmental factors play a key role in influencing the distribution of phytoplankton species in ECS. This study represents the first large-scale attempt in identifying HAB species in ECS in spring through ASV-based metabarcoding analysis. Results from this study will facilitate further comparative research on the molecular diversity and biogeography of HAB species, and monitoring HAB events in ECS.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102977"},"PeriodicalIF":4.5,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145106561","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":"Rare cyanobacteria drive nitrogen-fixation and cyanotoxin production in an Aphanizomenon-dominated bloom","authors":"Kaela E. Natwora ,&nbsp;Adam J. Heathcote ,&nbsp;Mark B. Edlund ,&nbsp;Shane E. Bowe ,&nbsp;Benjamin J. Kramer ,&nbsp;Jake D. Callaghan ,&nbsp;Cody S. Sheik","doi":"10.1016/j.hal.2025.102978","DOIUrl":"10.1016/j.hal.2025.102978","url":null,"abstract":"<div><div>Late summer, recurring cyanobacterial blooms in Lake of the Woods (LOW) are polycyanobacterial and typically dominated by <em>Aphanizomenon flos-aquae</em>. LOW waters are typically nitrogen limited, relative to phosphorus. As such, the dominance of <em>Aphanizomenon flos-aquae,</em> a putative nitrogen-fixing cyanobacterium, suggests that its ability to fix nitrogen may be advantageous and aid in its ability to bloom. This study sought to quantify nitrogen fixation rates and identify cyanotoxin-producing species during the blooms. Throughout the 2021 season, we quantified nutrients, N-fixation rates, microbial community composition, and gene expression to determine who is responsible for cyanotoxin synthesis and nitrogen fixation. We found nitrogen fixation rates increased throughout the season, coincided with the bloom, but likely cannot fully support the bloom’s nitrogen demand. However, the transcription of nitrogenase genes was solely done by less abundant <em>Dolichospermum</em> spp. and not by <em>A. flos-aquae.</em> Genome analysis suggests this population of <em>A. flos-aquae</em> cannot create a functioning nitrogenase, but they do still express the genes to initiate heterocyst differentiation. Microcystin gene transcripts were primarily from <em>Microcystis</em> spp. and <em>Planktothrix</em> spp. and coincided with microcystin concentrations. Interestingly, <em>Planktothrix</em> highly expressed anabaenopeptin genes, suggesting the presence of additional bioactive compounds in LOW. This work suggests that rare cyanobacterial members drive nitrogen fixation, and may be necessary for the seasonal bloom’s function, toxicity, and longevity.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102978"},"PeriodicalIF":4.5,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145106562","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":"Insights into the in vitro ichthyotoxicity on fish gill cells and toxin production of Karlodinium veneficum (Dinophyceae) strains from French waters","authors":"Rima Beesoo ,&nbsp;Kevin Hogeveen ,&nbsp;Fabienne Hervé ,&nbsp;Damien Réveillon ,&nbsp;Clémence Boucher ,&nbsp;Stéphanie Auzoux-Bordenave ,&nbsp;Valérie Fessard ,&nbsp;Roberto A. Avelar ,&nbsp;Nicolas Chomérat ,&nbsp;Gwenael Bilien ,&nbsp;Malwenn Lassudrie","doi":"10.1016/j.hal.2025.102980","DOIUrl":"10.1016/j.hal.2025.102980","url":null,"abstract":"<div><div>The dinoflagellate <em>Karlodinium veneficum</em> is regularly detected in French coastal waters; however, the ichthyotoxic potential of French strains and their ability to produce karlotoxins (KmTxs) remain unclear. This study aims to compare the bioactivity and KmTx profiles of four French strains and one previously characterized American strain of <em>K. veneficum</em> (used here as a reference), using the RTgill-W1 rainbow trout gill cell line. Both intracellular and releasable toxins (INT, EXT) in methanolic extracts were assessed for their effects using a resazurin-based assay, lactate dehydrogenase (LDH) release, mitochondrial membrane potential (TMRE dye), while liquid chromatography coupled to mass spectrometry was used to detect KmTxs. Cytotoxic activity varied depending on the strain and fraction, with IFR-CC-20–44 EXT (French) and CCMP 2936 INT (American) being the most toxic, while CBC7 (French) showed no toxicity. The French strains generally exhibited different cytotoxic mechanisms compared to the American strain. The KmTx profiles of the toxic strains showed an unexpectedly high chemodiversity with 93 KmTx-like molecules detected. Three French strains had similar KmTx profiles, dominated by KmTx-5 and a KmTx-5 analog. In contrast, the KmTx profile of the American CCMP 2936 was completely different to the French strains, with no KmTx in common. Interestingly, strain CBC7, which was non-toxic, did not produce any KmTxs. However, among the other <em>K. veneficum</em> strains, no clear link was established between the cytotoxicity of their extracts and total KmTx content. This may reflect differences in potency among KmTx analogs, although the involvement of other uncharacterized compounds cannot be excluded.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102980"},"PeriodicalIF":4.5,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145106955","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 modeling investigation into the ecological role of mixotrophy in Karenia brevis blooms on the West Florida Shelf","authors":"Yuren Chen ,&nbsp;Ming Li ,&nbsp;Patricia M. Glibert ,&nbsp;Cynthia Heil ,&nbsp;So Hyun Ahn","doi":"10.1016/j.hal.2025.102979","DOIUrl":"10.1016/j.hal.2025.102979","url":null,"abstract":"<div><div>While laboratory experiments show <em>Karenia brevis</em> graze on <em>Synechococcus</em> to supplement nutrition, the ecological role of mixotrophy in <em>K. brevis</em> blooms on the West Florida Shelf remains unquantified. This study employs a three-dimensional coupled hydrodynamic-biogeochemical model to investigate the contribution of mixotrophic feeding to the <em>K. brevis</em> growth as well as the role of mixotrophic grazing in suppressing prey population and delivering a competitive advantage to the mixotroph. It is shown that mixotrophy moderately increased the growth rate of <em>K. brevis</em> in the bloom center but was important along the offshore margin of the bloom region, where the prey-to-predator ratio was high. With the digestion rate reaching over 200 prey cells <em>K. brevis</em>^-1 day^-1, mixotrophy could support a heterotrophic growth rate of up to 0.16 day^-1 in the offshore region and may facilitate the offshore expansion of <em>K. brevis</em> blooms. Mixotrophic feeding also played a significant role in sustaining the <em>K. brevis</em> bloom during the late spring and summer periods when the inorganic nutrient concentrations were low. The grazing pressure exerted on <em>Synechococcus</em> was found to be vital for the slow-growing <em>K. brevis</em> to outcompete the oligotrophic-adapted prey. These model results demonstrate that mixotrophy not only functions as an additional nutrient source but also as an ecological mechanism that can reshape interspecific competition and harmful algal bloom dynamics.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102979"},"PeriodicalIF":4.5,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145106563","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":"Application of a hydrodynamic model to long-term monitoring data: exploring transport pathways to identify the source of high toxicity populations of Dinophysis fortii in aquaculture sites in northern Japan","authors":"Akira Miyazono ,&nbsp;Takanori Kuribayashi ,&nbsp;Yasufumi Hada ,&nbsp;Ken Asakura ,&nbsp;Kazuma Kobayashi ,&nbsp;Katsuhiko Mizuno ,&nbsp;Wai Mun Lum ,&nbsp;Sirje Sildever ,&nbsp;Hiroshi Kuroda ,&nbsp;Satoshi Nagai","doi":"10.1016/j.hal.2025.102976","DOIUrl":"10.1016/j.hal.2025.102976","url":null,"abstract":"<div><div>Diarrhetic Shellfish Toxicity (DST) occurs in northern Japan, Hokkaido and Tohoku, and is rarely observed in the southwest. A recent study using cultured strains of <em>Dinophysis fortii</em> revealed that high toxicity (HT) strains exist in northern Japan, while low-toxicity (LT) strains are found in the southwest. In this study, we analyzed 40 years of DST and plankton monitoring data from Hokkaido, eight years from Akita Prefecture, 33 years of oceanographic data from the Sea of Japan off northern Hokkaido, and the results of an ocean model experiment. The relationship between the annual DST maximum value and the cell density of <em>D. fortii</em> maxima in Hokkaido suggests the presence of both HT and LT strains. Results from the particle tracking experiment showed that transport of offshore populations of <em>D. fortii</em> to the coast is a key factor in HT DST events. Oceanographic data support that high DST along the Sea of Japan coasts in northern Hokkaido occurs in years of strong influence of the subarctic water of the Sea of Japan (SWSOJ). In northwestern Japan (Akita Prefecture), HT DST events were detected in years with strong influence of the second and third components of the Tsushima Warm Current (TWC2, 3) transporting particles from the SWSOJ. These results led to the conclusion that i) HT strains of <em>D. fortii</em> are transported by the SWSOJ reaching Hokkaido via its extension and Akita via the TWC2, 3, and ii) LT strains are transported to northern Japan via the first component of the Tsushima Warm Current (TWC1).</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102976"},"PeriodicalIF":4.5,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145059938","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}