Harmful Algae最新文献

{"title":"Comparative toxicity of Karlodinium veneficum from France and New Zealand on fish gill cells and oyster gametes","authors":"Anne Rolton ,&nbsp;Guillaume Barnouin ,&nbsp;Hannah Greenhough ,&nbsp;Audrey Duval ,&nbsp;Karthiga Kumanan ,&nbsp;Nelly Quéré Le Goïc ,&nbsp;Lucy Thompson ,&nbsp;Damien Réveillon ,&nbsp;Fabienne Hervé ,&nbsp;Andrew I. Selwood ,&nbsp;Hélène Hégaret ,&nbsp;Kirsty F. Smith ,&nbsp;Malwenn Lassudrie","doi":"10.1016/j.hal.2025.102991","DOIUrl":"10.1016/j.hal.2025.102991","url":null,"abstract":"<div><div>Harmful algal blooms (HABs) can cause mass mortalities of marine fauna, leading to major economic losses in aquaculture and fisheries worldwide. Toxicity varies widely among strains of the same HAB species, making broad assumptions of toxicity inaccurate. This study investigated the ichthyotoxic activity of <em>Karlodinium veneficum</em>, a HAB species of risk for aquaculture in France (FR) and New Zealand (NZ). Five <em>K. veneficum</em> strains (3 FR, 2 NZ) were cultured and extracted under standardized conditions. Following inter-laboratory assay comparison, crude (culture) and methanolic intra- and extracellular extracts were tested on <em>in vitro</em> models: rainbow trout gill cells (RTgill-W1) and Pacific oyster, <em>Crassostrea</em> (=<em>Magallana</em>) <em>gigas,</em> sperm.</div><div>Crude and methanolic extracts showed toxicity to both cell types, with variation between intra- (IN) and extracellular (EX) fractions. Of the crude extracts, only CAWD93 IN was toxic to gill and sperm cells, inducing 44 % and 81 % mortality, respectively, at 8.75 × 10⁴ equiv. cells mL^-1. Most methanolic extracts were toxic; MAR1F7 EX and CAWD93 IN induced the highest mortality rates, with EC₅₀’s reaching cell concentrations equivalent to high environmental bloom levels.</div><div>Karlotoxin analysis of methanolic extracts revealed distinct profiles by country. Karlotoxins were detected only in the three most toxic strains (MAR1F7, IFR-CC-20-44, CAWD93) and cytotoxicity was only weakly correlated with karlotoxin concentration, suggesting involvement of additional toxic compounds.</div><div>This study highlights strain-specific toxicity in <em>K. veneficum</em>, underscoring the importance of testing local HAB strains. The bioassays used offer a rapid, cost-effective, high-throughput, and ethical approach to evaluating HAB toxicity—crucial as ichthyotoxic blooms become more frequent globally.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102991"},"PeriodicalIF":4.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217318","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":"Identification of Gambierdiscus species from La Réunion and evaluation of toxicity and toxin profile","authors":"Lourdes Barreiro-Crespo ,&nbsp;Andres Sanchez-Henao ,&nbsp;Sandra Gimeno-Monforte ,&nbsp;Jaume Reverté ,&nbsp;Mònica Campàs ,&nbsp;María García-Altares ,&nbsp;Alina Tunin-Ley ,&nbsp;Fanny Maillot ,&nbsp;Cintia Flores ,&nbsp;Nicolas Chomérat ,&nbsp;Gwenaël Bilien ,&nbsp;Takeshi Tsumuraya ,&nbsp;Núria Fontanals ,&nbsp;Francesc Borrull ,&nbsp;Jean Turquet ,&nbsp;Jorge Diogène ,&nbsp;Maria Rambla-Alegre","doi":"10.1016/j.hal.2025.103003","DOIUrl":"10.1016/j.hal.2025.103003","url":null,"abstract":"<div><div>Five different species of <em>Gambierdiscus</em> have been identified in La Réunion (<em>G. belizeanus, G. balechii, G. pacificus, G. silvae</em> and <em>G</em>. ribotype 2) by morphological observations in Scanning Electron Microscopy (SEM) and molecular identification and phylogenetic analysis. Growth rates of cultures have also been evaluated showing values from 0.09 to 0.36 <span>d</span>^-1.</div><div>The toxicity and toxin profile of thirteen strains have been analysed by a multidisciplinary approach with Neuro-2a cell-based assay (CBA), magnetic bead-based immunoassay, liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) and LC coupled to high-resolution mass spectrometry (LC<img>HRMS). <em>G. balechii</em> showed the highest toxicity by CBA (∼627 fg equiv. CTX1B·cell ^-1) followed by <em>G.</em> ribotype 2 (76 to 13 fg equiv. CTX1B·cell ^-1), <em>G. balechii</em> (63 to 7 fg equiv. CTX1B·cell ^-1), <em>G. belizeanus</em> (30 to 20 fg equiv. CTX1B·cell ^-1) and <em>G. pacificus</em> with values close to LOQ but not conclusive. The toxin profile for the 13 strains was evaluated by LC-MS/MS using seven different methods and being gambierone and 44-methylgambierone the two only known compounds, found in high concentrations in all samples. Gambierone was detected from 2.05 pg ·cell^-1 in <em>G. balechii</em> (P-0414B) to 12.91 pg·cell^-1 in <em>G. balechii</em> (P-0414A) and 44-methylgambierone was detected from 1.93 pg·cell^-1 in <em>G. belizeanus</em> (P-0414B) to 14.95 pg·cell^-1 in <em>G. pacificus</em> (P-0304). These samples were analysed also by LC<img>HRMS, confirming gambierone and 44-methylgambierone the main compounds detected. Additionally, a potential polyether sulphur-containing compound corresponding to the novel molecular formula C₆₂H₉₄O₂₃S ([M+NH₄]⁺, <em>m/z</em> 1256.6234) were tentatively identified.</div><div>This study combining morphological and molecular data is the first to mention such diversity in the area. It is also the first time that toxicity and toxin profile of <em>Gambierdiscus</em> from La Réunion have been evaluated.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 103003"},"PeriodicalIF":4.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145358091","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":"Sub-lethal effects of natural cyanobacterial blooms on fish: Enzymatic activity and swimming performance in Gasterosteus aculeatus","authors":"Francesco Masnadi ,&nbsp;Xuewei Qi ,&nbsp;John M. Taylor ,&nbsp;Joachim Sturve ,&nbsp;Valentina Di Santo ,&nbsp;Agnes M.L. Karlson","doi":"10.1016/j.hal.2025.102965","DOIUrl":"10.1016/j.hal.2025.102965","url":null,"abstract":"<div><div>Cyanobacterial blooms are intensifying worldwide due to eutrophication and climate change, increasing cyanotoxin exposure to aquatic organisms. This study investigated the physiological, biochemical, and behavioural impacts of cyanobacterial blooms on the three-spined stickleback (<em>Gasterosteus aculeatus</em>), a widespread mesopredatory fish. Adult sticklebacks were exposed for two weeks to naturally collected bloom material dominated by toxic <em>Nodularia spumigena</em>, non-toxic <em>Aphanizomenon</em> sp., or a 50:50 mix. We measured toxin accumulation (NOD_eq), hepatic enzymatic activities (ethoxyresorufin-O-deethylase [EROD], glutathione S-transferases [GSTs], glutathione reductase [GR], and catalase [CAT]), and escape swimming performance (centre-of-mass velocity, angular velocity, distance, and duration) in a multiparametric endpoints approach. Sub-lethal toxin levels in muscle tissue ranged from 0.006 to 0.077 µg g⁻¹ d.w. Results showed that fish exposed to toxic-dominated treatments showed significantly elevated EROD activity (up to 200 % increase), moderate increases in GR and GSTs, and reduced CAT activity compared to controls. Notably, distance travelled during escape responses was reduced by ∼50 % in the high-toxicity treatment and showed an inverse correlation with EROD activity, suggesting a trade-off between detoxification effort and swimming performance. Overall, our results demonstrate that EROD is a sensitive biomarker for cyanotoxin exposure in fish under natural bloom conditions. This finding highlights the need to consider natural cyanotoxin effects when interpreting environmental assessments, particularly given the projected increase in bloom frequency and severity under future climate scenarios.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102965"},"PeriodicalIF":4.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145005228","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":"Two dueling Dolichospermum strains in an Oregon lake determine occurrence of cyanotoxic blooms","authors":"Theo W. Dreher ,&nbsp;Connie S. Bozarth ,&nbsp;Jonathan W. Shepardson ,&nbsp;Norman L. Buccola ,&nbsp;Ryan S. Mueller ,&nbsp;Elijah Welch ,&nbsp;Claudia S. Maier","doi":"10.1016/j.hal.2025.102993","DOIUrl":"10.1016/j.hal.2025.102993","url":null,"abstract":"<div><div>There is a common perception that cyanobacterial harmful algal blooms (CyanoHABs) occur relatively consistently over consecutive years in a given lake or reservoir. Description of the CyanoHAB properties of a lake should thus be a useful managerial tool allowing the development of monitoring tools focused on problem cyanobacteria, particularly those producing cyanotoxins. We describe the characterization of CyanoHABs in Detroit Lake, Oregon, over a 12-year period. This time span encompassed two periods of relatively consistent CyanoHABs, but also a marked shift occurring between the two extended periods of stability. During 2012–2017, CyanoHABs in Detroit Lake consisted of short-lived (∼2 weeks) early-season blooms producing high levels of 7‑epi-cylindrospermopsin (CYN); very little microcystin (MC) was present. 2018 was a year in which levels of both CYN and MC were high, with MC produced from mid-May through July. During 2019–2024, MC concentrations were typically higher than CYN, and the early season CYN peaks were much lower than in previous years. Detroit Lake thus appears to have experienced two distinct periods of CyanoHAB character during the decade of study. We infer these changes to reflect changes in the dynamics of the two known cyanotoxin-producing <em>Dolichospermum</em> strains, <em>Dolichospermum</em> sp. DET 69 (CYN-positive) and <em>Dolichospermum</em> sp. DET73 (MC-positive), which appear to be the only significant cyanotoxin producers among the lake’s planktonic phytoplankton community. Occasional HABs dominated by nontoxigenic <em>Aphanizomenon flos-aquae</em> and <em>Gloeotrichia echinulata</em> were also a feature of the later years, although <em>Dolichospermum</em> spp. were the dominant cyanobacteria during most of the bloom season. This study illustrates how a lake’s CyanoHABs profile can change even in the absence of obvious changes in management or surrounding land use, and how an in-depth study of the CyanoHABs occurring in a lake over a few years can identify the problematical cyanobacteria and provide the information for developing a monitoring program targeting the HABs they produce.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102993"},"PeriodicalIF":4.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145266756","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":"2025-12-01","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":"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":"2025-12-01","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":"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":"2025-12-01","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":"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":"2025-12-01","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":"More sustained, more severe blooms and shifting monthly patterns of the toxigenic dinoflagellate Karenia brevis on the West Florida Shelf","authors":"Patricia M. Glibert ,&nbsp;Cynthia A. Heil ,&nbsp;Ming Li","doi":"10.1016/j.hal.2025.102967","DOIUrl":"10.1016/j.hal.2025.102967","url":null,"abstract":"<div><div>Various recent reports, based on different approaches, data sets and time periods, have yielded different conclusions with regard to whether blooms of the Florida red tide dinoflagellate, <em>Karenia brevis</em>, have increased over time. Without question, however, there have been a number of recent blooms that have been long lasting, continuing through the summer months normally taken to be outside the ideal temperature niche for <em>K. brevis</em>. Here, using a recently developed bloom severity index, the time series of blooms from 1970 to 2019 is examined, focusing on how monthly patterns have changed over time. More severe blooms have been found since the mid 1990s, now lasting 4- to 5-months longer than in previous decades, a trend related to the Oceanic Niño Index (El Niño -Southern Oscillation). Since the mid-1990s, water temperature anomalies have been related to bloom severity with lags of 3 to 6 months. The most significant temperature increases have occurred in the latter months of the year when <em>K. brevis</em> growth typically is highest. Increased flow from the Caloosahatchee River, and its total nitrogen load, are also predictors of recent bloom severity with lags of several months. Cells that survive the now-warmer winter dry season have adequate nutrients and may experience more favorable nitrogen forms as the summer wet season develops, and as nutrients are recycled, may “over summer”. The stresses of increased warming and increased nutrient pollution on <em>K. brevis</em> blooms will continue to make managing these blooms a challenge for management as climate change trajectories continue.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102967"},"PeriodicalIF":4.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145047216","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":"Mechanistic insights into Ginkgo-nerolidol compound preparation against the bloom-forming dinoflagellate Prorocentrum donghaiense","authors":"Anglu Shen ,&nbsp;Aixue Qian ,&nbsp;Wuyou Shen ,&nbsp;Xinfeng Dai ,&nbsp;Liu Shao","doi":"10.1016/j.hal.2025.102994","DOIUrl":"10.1016/j.hal.2025.102994","url":null,"abstract":"<div><div><em>Prorocentrum donghaiense</em> is a major bloom-forming species in the East China Sea and has severe adverse effects on marine ecosystems. To address this issue, the development of efficient and eco-friendly algal inhibitors is essential. However, research in this area remains limited. In this study, <em>Ginkgo biloba</em> extract (GB), nerolidol (NE), and a compound preparation (GN = GB + NE) were selected as algae-inhibiting materials, and the mechanisms of action of GB, NE, and GN on <em>P. donghaiense</em> were analyzed via RNA-seq. In total, 59,151, 152, and 25,363 differentially expressed genes (DEGs) were identified in algae treated with GB, NE, and GN, respectively. The top three GO- and KEGG-annotated DEGs were shared between GB and GN treatments, indicating that GB was the primary active component of GN. KEGG enrichment further showed that photosynthesis-related pathways were among the top five pathways affected by GN. Key genes in photosystem II (<em>PsbA-E</em>), cytochrome <em>b₆/f</em> complex (<em>PetD</em>), and ATP synthase (<em>atpD</em>) were downregulated, and 10 photosynthesis-antenna protein genes (<em>Lhca1–4, Lhcb1–6</em>) were upregulated under GN treatment. However, most of these genes did not show significant expression under the GB treatment, except for <em>Lhca1</em> and <em>Lhcb1–2</em>. Furthermore, NE treatment upregulated <em>ushA</em> and downregulated <em>pncC</em>, disrupting algal nucleotide and NAD⁺ biosynthesis. This suggests that NE may accelerate GB-induced inhibition of photosynthesis-related pathways. These findings provide new insights into the molecular mechanisms underlying <em>P. donghaiense</em> exposure to GN and provide a theoretical basis for the prevention and control of harmful algal blooms.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102994"},"PeriodicalIF":4.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217317","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}