Harmful Algae最新文献

{"title":"The ornithine-arginine cycle supported a toxic, metalimnic Planktothrix rubescens bloom","authors":"Brittany N. Zepernick ,&nbsp;David J. Niknejad ,&nbsp;Emily E. Chase ,&nbsp;Blessing A. Abiodun ,&nbsp;Meaghan J. Adler ,&nbsp;Katelyn A. Houghton ,&nbsp;Jason L. Olavesen ,&nbsp;Qudus Sarumi ,&nbsp;Alexander R. Truchon ,&nbsp;Jillian L. Walton ,&nbsp;Jack H. Cheshire ,&nbsp;Keara Stanislawczyk ,&nbsp;Lauren N. Hart ,&nbsp;Hans W. Paerl ,&nbsp;Justin D. Chaffin ,&nbsp;Gregory L. Boyer ,&nbsp;Hector F. Castro ,&nbsp;Shawn R. Campagna ,&nbsp;George S. Bullerjahn ,&nbsp;Steven W. Wilhelm","doi":"10.1016/j.hal.2025.103008","DOIUrl":"10.1016/j.hal.2025.103008","url":null,"abstract":"<div><div><em>Planktothrix rubescens</em> is distinct from other cyanobacterial harmful algal bloom (cHAB) genera: the crimson-red cHAB thrives in the cold, low-light, nutrient-limited metalimnion. Studies have attributed this ecological success to buoyancy regulation, low-light adaptations, and the uptake of nitrogen-rich amino acids. Yet, it remains to be mechanistically determined how this cHAB maintains physiological nutrient quotas in the metalimnion due to limited <em>in situ</em> molecular studies. We employed metagenomics and metabolomics to generate hypotheses concerning a toxigenic <em>P. rubescens</em> bloom in Mead's Quarry (Knoxville, TN, USA) observed in two separate years. Our results suggest a perennial, metalimnic <em>P. rubescens</em> population may exist, with spring turnover facilitating seasonal migration to the epilimnion. Although <em>P. rubescens</em> dominated the epilimnion and metalimnion, intracellular metabolite pools grouped by depth and suggested depth-discrete partitioning of the arginine deiminase-mediated ornithine-arginine cycle (OAC, <em>i.e.,</em> urea cycle) – while further indicating the presence of the arginine catabolic pathway. Though the arginine influx driving the OAC is unclear, we hypothesize this input is provided <em>via</em> the uptake of urea or nitrogen-rich amino acids. Further, we demonstrate arginine deiminase (<em>agrE/argZ</em>) is broadly distributed in <em>Planktothrix</em> genera and known microcystin producers, suggesting <em>agrE/argZ</em>-mediated arginine metabolism and the OAC may influence the fitness of toxigenic cHAB genera which require ample nitrogen to synthesize microcystins. Cumulatively, our results serve as a case study to provide insight on the metabolic pathways driving the ecological success of metalimnic <em>P. rubescens</em> blooms. On a broader scale, this work strengthens the case that alternative nitrogen metabolism – including urea utilization, amino acid catabolism, and the OAC – is a driver of toxigenic cHABs in fresh waters.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"151 ","pages":"Article 103008"},"PeriodicalIF":4.5,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145527431","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":"Cyanotoxin production in shallow subtropical lakes is driven by nutrient enrichment and primary producer abundance on the millennial scale","authors":"Savvas Paradeisis-Stathis ,&nbsp;Matthew N. Waters ,&nbsp;Debra A. Willard ,&nbsp;Sophia Foliano ,&nbsp;Richard S. Vachula","doi":"10.1016/j.hal.2025.103004","DOIUrl":"10.1016/j.hal.2025.103004","url":null,"abstract":"<div><div>Increased cyanotoxin concentrations from harmful algal blooms (HABs) in lake systems pose a global challenge to water quality. Although progress has been made in monitoring cyanotoxins in modern environments over recent decades, identifying the triggers of cyanotoxin release by cyanobacteria has yielded mixed results from experimental and analytical studies. Paleolimnological reconstructions can reveal whole-lake long-term changes, but few studies have directly measured cyanotoxins alongside other water quality proxies. Here, we investigated the drivers of sedimentary total microcystin (MC) concentrations on millennial scales in hypereutrophic Lakes Dora and Marian in central Florida, USA. We analyzed dated sediment records using paleolimnological techniques to reconstruct nutrient deposition, cyanobacteria abundance (photosynthetic pigments), and cyanotoxins (total MCs). The objective was to investigate the linkage between MC concentrations in the sediments with both biotic (cyanobacteria and other primary producers) and abiotic factors (nutrients and climate). We found that MC production occurred throughout the ∼7000-year period, progressing from periods of moderate to low, and then to high concentrations in both lakes. Statistical analyses showed that historical MC concentrations were correlated with sedimentary measurements of total phosphorus (TP), cyanobacteria abundance, and other primary producer groups, such as cryptophytes. However, there was only a minimal correspondence with climate proxies, such as charcoal and pollen, suggesting that internal nutrient cycling and human pressures were the dominant drivers of MC deposition. Our study demonstrates that cyanotoxins have occurred for millennia in both lakes with maintained relationships to nutrients and other environmental factors that existed both in historic and modern limnological conditions.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"151 ","pages":"Article 103004"},"PeriodicalIF":4.5,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145465113","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":"Taxonomy, distribution, and habitat associations of Gambierdiscus from coastal waters off Queensland, Australia","authors":"Joseph C. Perkins ,&nbsp;Kyall R. Zenger ,&nbsp;Angela Capper ,&nbsp;Yang Liu ,&nbsp;Jan M. Strugnell","doi":"10.1016/j.hal.2025.103006","DOIUrl":"10.1016/j.hal.2025.103006","url":null,"abstract":"<div><div>Ciguatera poisoning is the most prevalent non-bacterial seafood illness globally, with an estimated 10,000 to 50,000 cases reported annually. It is caused by consumption of seafood (mainly fish) that have accumulated ciguatoxins produced primarily by benthic dinoflagellates of the genus <em>Gambierdiscus</em>. Ciguatera poses a significant public health and fisheries challenge in tropical and subtropical regions. Although these dinoflagellates are widespread across tropical and subtropical marine ecosystems, their ecology, taxonomy, and environmental drivers remain poorly understood in many regions, limiting the capacity to monitor and predict ciguatera risk. This study uses DNA metabarcoding (targeting the V8-V9 regions of the 18S rRNA gene) to investigate the diversity, spatial distribution, and ecological associations of <em>Gambierdiscus</em> species across multiple coastal sites in Queensland, Australia. Results revealed the distribution of known species (<em>G. carpenteri, G. holmesii</em>) and several potential new phylotypes, notably a genetically distinct group (Clade II GBR) that may represent an undescribed lineage. Importantly, this study provides the first confirmed detection of <em>G. holmesii</em>, a known ciguatoxin producer, in Hervey Bay and Gladstone, extending its known geographic range from offshore to inshore reefs and coastal habitats of the Great Barrier Reef. This study is also the first documented record of any <em>Gambierdiscus</em> taxa in the Gladstone coastal region. Taxa composition was influenced by macroalgal host, and shallow coral reef habitats supported the highest species diversity and detection frequency, suggesting their role as ecological hotspots. Canonical correspondence analysis (CCA) identified associations between species and macroalgal hosts, including a strong link between <em>G. holmesii</em> and <em>Cladophora</em> sp., while <em>G. carpenteri</em> showed no specific host preference. Overall, this study provides ecological characterisation of <em>Gambierdiscus</em> communities across diverse tropical and subtropical habitats in Queensland, contributing to regional ciguatera risk assessment and global efforts to understand the ecology and distribution of benthic toxic dinoflagellates.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 103006"},"PeriodicalIF":4.5,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145416595","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":"Differential responses and adaptive mechanisms of diatoms and dinoflagellates to changes in dissolved organic nitrogen components","authors":"Haoyu Zhang ,&nbsp;Cui Zeng ,&nbsp;Xiansheng Zhang ,&nbsp;Xiulin Wang ,&nbsp;Keqiang Li","doi":"10.1016/j.hal.2025.103005","DOIUrl":"10.1016/j.hal.2025.103005","url":null,"abstract":"<div><div>Dissolved organic nitrogen (DON) composition critically influences phytoplankton community dynamics, yet the species-specific regulatory mechanisms remain unclear. Combining cultivation experiments and transcriptomics, we reveal distinct growth responses of the diatom <em>Chaetoceros curvisetus</em> and dinoflagellate <em>Prorocentrum minimum</em> to three DON components: plant-derived peptides in labile DON (LDON_P) as well as animal manure–derived humic in semilabile DON (SDON_H) and fulvic acids in refractory DON (RDON_F). Diatoms exhibited superior LDON_P utilization via upregulated nitrogen metabolism genes (<em>gdhA, GLT1, glnA</em>) and peptide transporters (<em>PTR</em>), while dinoflagellates dominated SDON_H assimilation through endocytosis-associated gene activation (<em>PLD, PIP5K</em>) and enhanced photosystem efficiency. RDON_F inhibited both species but triggered energy reallocation to the TCA and Calvin cycles. Fluorescence spectroscopy further linked bioavailability to molecular structure, with diatoms efficiently utilizing protein-like components (T) and dinoflagellates preferentially absorbing humic-like components (E). This study proposed a genomic insight of diatoms and dinoflagellates growth into adaptation to DON regimes. Ecologically, the molecular mechanistic framework might predict phytoplankton succession under shifting DON regimes in coastal ecosystems. These findings provide strategies to mitigate harmful algal blooms in eutrophic coastal waters through DON source management.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 103005"},"PeriodicalIF":4.5,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145358093","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":"2025-10-16","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":"A newly developed Germlings Harvester (GEHA) in combination with metabarcoding analysis detected numerous plankton species, particularly HABs-causing species, from in-situ germination of resting stage cells","authors":"Shuo Shi ,&nbsp;Zhe Tao ,&nbsp;Wanli Yang ,&nbsp;Fengting Li ,&nbsp;Ben Wei ,&nbsp;Caixia Yue ,&nbsp;Suzhi Pan ,&nbsp;Yunyan Deng ,&nbsp;Lixia Shang ,&nbsp;Zhaoyang Chai ,&nbsp;Ying Zhong Tang","doi":"10.1016/j.hal.2025.103002","DOIUrl":"10.1016/j.hal.2025.103002","url":null,"abstract":"<div><div>Germination of resting-stage cells (RSCs), including the resting cysts of dinoflagellates and raphidophytes and resting spores of diatoms, of plankton influence community composition, species abundance, and population dynamics, particularly the initiation of harmful algal blooms (HABs), in aquatic ecosystem. While the vital role played by resting cysts in seeding HABs has been well known in the HABs research community, in-situ detection of RSCs germination in the field sediment, however, remains largely unexplored due to the lack of feasible facility and accurate identification method, and many important groups of plankton have even not been systematically investigated for their life histories. We therefore developed a facility, named Germlings Harvester (GEHA), for the in-situ detection of the species diversity of plankton RSCs, particularly those with vital importance, that germinated from the natural marine sediment. Using GEHA in combination with eukaryote-targeted metabarcoding analysis and other approaches in Jiaozhou Bay, China, we identified 220 planktonic species germinated in situ, including 51 species of Dinoflagellata, 54 Bacillariophyta, 16 Ochrophyta, 18 Chlorophyta, 9 Haptophyta, 31 Ciliophora, 2 Euglenozoa, 3 Amoebozoa, and 36 others. Among these species, 38 are HABs-causing or toxic (notably <em>Akashiwo sanguinea, Azadinium polongum, Karlodinium veneficum, Margalefidinium fulvescens, Prorocentrum donghaiense, Pseudonitzschia</em> spp<em>., Heterosigma akashiwo, Aureococcus anophagefferens</em>, and <em>Phaeocystis globosa</em>, all being observed for their in-situ germinations of RSCs in the field for the first time), one ciliate reported to form “red tides”, and five parasites reported highly harmful to their hosts. It is also noteworthy that 128 of the 220 species were observed as novel RSC producers, and four are freshwater species. In addition, eight germinated species isolated from the germlings with GEHA were identified via establishing clonal cultures and sequencing or single-cell sequencing (e.g., <em>A. sanguinea</em>). Our results demonstrated not only the robustness of the GEHA-based approach in the field investigation of plankton population dynamics and particularly HABs ecology from the facet of germination dynamics of RSCs (cysts, spores and akinetes), but also their vital importance in understanding the general ecology of plankton and aquatic ecosystems and in the monitoring and forecasting of HABs.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 103002"},"PeriodicalIF":4.5,"publicationDate":"2025-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321123","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":"Grazing-induced cellular responses in toxic diatom Pseudo-nitzschia multiseries","authors":"Yuelei Dong ,&nbsp;Huiling Wang ,&nbsp;Wenqing Jiang ,&nbsp;Kaiyin Wu ,&nbsp;Panyu Chen ,&nbsp;Jianwei Zheng ,&nbsp;Xin Guo ,&nbsp;Lei Cui ,&nbsp;Yang Li","doi":"10.1016/j.hal.2025.102998","DOIUrl":"10.1016/j.hal.2025.102998","url":null,"abstract":"<div><div>Blooms of <em>Pseudo-nitzschia</em> are frequent in coastal areas, and many species have been confirmed to synthesize the neurotoxin domoic acid (DA). DA accumulates in filter-feeding marine organisms, posing a threat to human health. Grazing on <em>Pseudo-nitzschia</em> is considered a factor that affects the production of DA. There is a substantial body of literature focusing on the biotic and abiotic factors that influence DA accumulation, while the detailed molecular processes within the algal cells remain largely unexplored. Using co-culture of <em>Pseudo-nitzschia multiseries</em> and <em>Artemia salina</em> nauplii, we integrated multi-omics and physiological analyses to investigate the defense mechanisms of <em>P. multiseries</em> against grazing. The data revealed increased levels of secondary metabolites such as DA (0.20 pg/cell/day) and jasmonic acid (1.88-fold increase, by metabolomics), decreased metabolic efficiency, enhanced photosynthetic efficiency, and reduced cell growth rates. These observations suggest that algal cells respond to grazing by modulating their biochemical composition and energy metabolism pathways. Our findings provide a molecular basis for the resistance of toxic diatoms to grazing pressure.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102998"},"PeriodicalIF":4.5,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321121","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":"Ranking the cytotoxic potency of Ostreopsis cf. ovata, Ostreopsis cf. siamensis (O. sp. 9), and purified ovatoxins in human keratinocytes","authors":"Loïc Plessis ,&nbsp;Korian Lhaute ,&nbsp;Fabienne Hervé ,&nbsp;Madeleine Thimann ,&nbsp;Véronique Séchet ,&nbsp;Liliane Carpentier ,&nbsp;Ariana B. Moutinho ,&nbsp;Tiago Simões ,&nbsp;Ana Amorim ,&nbsp;Kevin Henry ,&nbsp;Jorge L.B. Neves ,&nbsp;Léana Gorse ,&nbsp;Margaux Paradis ,&nbsp;Stéphanie Brédif ,&nbsp;Philipp Hess ,&nbsp;Damien Réveillon","doi":"10.1016/j.hal.2025.103000","DOIUrl":"10.1016/j.hal.2025.103000","url":null,"abstract":"<div><div>Ovatoxins (OVTXs), a family of marine polyketides structurally similar to palytoxin (PLTX), are suspected to cause respiratory symptoms and skin irritation among coastal users during blooms of the dinoflagellate <em>Ostreopsis</em> cf. <em>ovata</em>. To investigate their role in cutaneous toxicity, crude extracts from six <em>O.</em> cf. <em>ovata</em> strains (OVTX(+) and OVTX(−)) and three <em>O.</em> cf. <em>siamensis</em> (<em>O</em>. sp. 9) strains (OVTX(−)), along with six purified OVTX analogs, were tested for cytotoxicity (MTT assay) and cell death phenotypes (microscopy) in human keratinocyte models. Interestingly, cytotoxicity was driven by OVTX content, while OVTX(−) extracts were, on average, 150-fold and &gt;1000-fold less potent for <em>O.</em> cf. <em>siamensis</em> and <em>O.</em> cf. <em>ovata</em>, respectively. Nevertheless, the latter two induced PLTX-like cell death, suggesting the presence of unidentified PLTX-like toxins. Purified OVTXs exhibited sub-nanomolar cytotoxicity, 3.5- to 12.5-fold lower than PLTX (IC₅₀ = 0.036–0.642 nM vs. 0.011–0.049 nM), ranking in potency: PLTX &gt; OVTX-d &gt; OVTX-b &gt; OVTX-a &gt; OVTX-c &gt; OVTX-e &gt;&gt;&gt; OVTX-h (non-toxic, likely due to ring-opening). This study demonstrates the high toxic potency of OVTXs, close to that of PLTX, while providing a comprehensive cytotoxicity assessment of OVTX analogs, which could be useful for assessing the risks of human exposure.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 103000"},"PeriodicalIF":4.5,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145358092","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":"Exposure to harmful algal blooms and socio-demographic patterns: Evidence from six decades of analysis in Florida, USA","authors":"Hao Chen ,&nbsp;Haoluan Wang","doi":"10.1016/j.hal.2025.102999","DOIUrl":"10.1016/j.hal.2025.102999","url":null,"abstract":"<div><div>Harmful algal blooms (HABs) have emerged as a critical environmental hazard in U.S. coastal waters, posing substantial risks to human health. This study examines six decades of HAB events (1960–2019) across 34 coastal counties in Florida, USA, to evaluate the relationship between HAB exposure and socio-demographic patterns. We further use the Gini coefficient to measure spatial disparities in exposure, with a particular focus on children and seniors, two groups especially vulnerable to environmental hazards. Our analysis reveals that HAB exposure is significantly linked to population decline and a reduced proportion of children in affected counties. In contrast, areas with greater HAB exposure tend to have a higher share of senior residents. Notably, spatial inequality is evident: counties with fewer children generally experience greater exposure, while those with more seniors face disproportionately higher exposure. These findings underscore the importance of addressing environmental justice in policy responses to HABs.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102999"},"PeriodicalIF":4.5,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321124","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":"From human-driven eutrophication to effective management: Controlling brown tides in the coastal waters of Qinhuangdao, China","authors":"Lei Cui ,&nbsp;Yue-Lei Dong ,&nbsp;Jian-Le Zhang ,&nbsp;Wei-Dong Yang ,&nbsp;Song-Hui Lu ,&nbsp;Lin-Jian Ou","doi":"10.1016/j.hal.2025.102997","DOIUrl":"10.1016/j.hal.2025.102997","url":null,"abstract":"<div><div>The coastal waters of Qinhuangdao, Bohai Sea, China, experienced recurrent brown tides caused by <em>Aureococcus anophagefferens</em> from 2009 to 2015, severely impacting scallop mariculture and coastal tourism. While eutrophication is a global phenomenon, <em>A. anophagefferens</em> blooms have been reported only in a small number of isolated ocean regions first in the USA and South Africa, and more recently in the coastal waters of Qinhuangdao, Bohai Sea, China. Mechanisms underlying such few isolated bloom patterns remain to be addressed. This study integrates historical water quality data, socioeconomic statistics, and field observations to investigate how rapid urbanization, industrialization, and agricultural development in the Qinhuangdao region, combined with intensive shellfish mariculture in the adjacent coastal waters, contributed to bloom formation. Increased nutrient loading—particularly dissolved organic nitrogen from land-based runoff and mariculture—together with phosphorus limitation (indicated by high ratios of inorganic nitrogen to phosphorus) and restricted water exchange, created conditions favorable for <em>A. anophagefferens</em>, consistent with global understanding of its bloom ecology. Genetic evidence suggests either ballast water introduction or indigenous activation from dormant sediment populations. Since 2012, comprehensive environmental policies, including wastewater treatment and aquaculture restructuring, have significantly reduced nutrient loads and improved water quality, leading to the cessation of brown tides after 2015 and a ∼95 % reduction in other harmful algal blooms (HABs) by 2018–2020. The Qinhuangdao case underscores the strong linkage between anthropogenic activities and HABs and provides a transferable management framework for other vulnerable coastal systems.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102997"},"PeriodicalIF":4.5,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145266753","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}