Harmful Algae最新文献

{"title":"Urban eutrophication enhances domoic acid production by Pseudo-nitzschia in the Southern California Bight","authors":"Marco Sandoval-Belmar ,&nbsp;Faycal Kessouri ,&nbsp;Jayme Smith ,&nbsp;Allison R. Moreno ,&nbsp;Clarissa Anderson ,&nbsp;Raphael M. Kudela ,&nbsp;Martha Sutula ,&nbsp;Minna Ho ,&nbsp;Pierre Damien ,&nbsp;Claudia Benitez-Nelson ,&nbsp;James C. McWilliams ,&nbsp;Daniele Bianchi","doi":"10.1016/j.hal.2025.103023","DOIUrl":"10.1016/j.hal.2025.103023","url":null,"abstract":"<div><div>The diatom genus <em>Pseudo-nitzschia</em> and its neurotoxin domoic acid (DA) are major contributors to harmful algal blooms (HABs) along the U.S. West Coast, affecting marine ecosystems and human health. Observations implicate anthropogenic nutrient inputs, upwelling, and climate variability, but their relative importance remains unclear. We couple a mechanistic DA-production model, constrained by culture experiments, to a three-dimensional ocean biogeochemical model to simulate the DA cycle in the Southern California Bight, an urbanized region with a population of 23 million. Using 1-km resolution simulations for 2006–2017 we compare two cases: (i) an anthropogenic scenario (ANTH), in which rivers and wastewater outfalls supply freshwater and enhanced nutrient loads, and (ii) a control (CTRL) with freshwater-only fluxes, and nutrient loads set to zero. Skill assessments show that ANTH captures observed seasonal patterns, vertical distributions, and horizontal gradients of particulate DA. Performance is highest in the San Pedro and Santa Barbara Channels, but lower elsewhere, indicating need for refinements to capture local HAB dynamics. Comparison of the two simulations shows that terrestrial nitrogen inputs enhance coastal diatom production and shift nutrient limitation from nitrogen to silica, amplifying DA production. Surface particulate DA along the coast increases on average by <span><math><mo>∼</mo></math></span>25% with anthropogenic inputs, suggesting a substantial enhancement of the region’s natural susceptibility to DA events. This study advances our ability to disentangle natural versus human drivers of <em>Pseudo-nitzschia</em> HABs, quantifying the role of anthropogenic inputs among the drivers of DA production in the Bight.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"151 ","pages":"Article 103023"},"PeriodicalIF":4.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577567","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 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":"2026-01-01","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":"A digital PCR assay for the dabA gene involved in domoic acid biosynthesis by Pseudo-nitzschia spp","authors":"Chloe Weinstock ,&nbsp;Christina Preston ,&nbsp;John K. Brunson ,&nbsp;William Ussler ,&nbsp;Holly Bowers ,&nbsp;Kevan Yamahara ,&nbsp;Greg Doucette ,&nbsp;John Ryan ,&nbsp;Andrew Allen ,&nbsp;Christopher Scholin ,&nbsp;James Birch","doi":"10.1016/j.hal.2025.103024","DOIUrl":"10.1016/j.hal.2025.103024","url":null,"abstract":"<div><div>Successful harmful algal bloom (HAB) prediction and monitoring employs a variety of observational and research strategies. We add to the existing suite of tools for detecting toxigenic <em>Pseudo-nitzschia</em> diatoms by developing a novel digital PCR (dPCR) assay targeting a key gene of the domoic acid biosynthetic pathway, dabA. Sequence alignments and synthetic gene fragments of dabA genes from <em>Pseudo-nitzschia australis, P. multiseries, P. multistriata</em>, and <em>P. seriata</em>, along with the closely-related red-algal genes kabA and radA, were used to design a dPCR assay and assess its specificity. This dPCR assay was demonstrated to be specific for dabA and can quantify concentrations &gt;1 copy µL^-1 in a reaction. The biogeography of published dabA genes suggests that the assay may be useful globally for target species. When screening a culture collection of <em>Pseudo-nitzschia</em> isolated from coastal California, the dPCR assay detected dabA genes from three of the eleven species tested<em>.</em> In samples collected during field campaigns in 2022 off Santa Barbara, CA and in 2023 in Monterey Bay, CA during toxic HAB events, <em>Pseudo-nitzschia</em> dabA genes were only detected in Monterey Bay samples. While the dPCR assay does not capture all dabA diversity, it is specific and provides a targeted means to assess the genetic potential of a toxic HAB event by dominant and potent toxin-producing <em>Pseudo-nitzschia</em> species in coastal California. Because dabA expression is a key indicator of DA production, using the assay to quantify gene transcription could speed the acquisition of data needed to forecast HABs before toxin is detected.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"151 ","pages":"Article 103024"},"PeriodicalIF":4.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577596","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":"Morphological, molecular and toxinological characterization of potentially toxigenic microalgal strains from the western Black Sea","authors":"Fuat Dursun ,&nbsp;Nina Dzhembekova ,&nbsp;Bernd Krock ,&nbsp;Jan Tebben ,&nbsp;Urban Tillmann","doi":"10.1016/j.hal.2025.103026","DOIUrl":"10.1016/j.hal.2025.103026","url":null,"abstract":"<div><div>Harmful algal blooms (HAB) of various toxic microalgae negatively affect the Black Sea but there is limited data on the sources of phycotoxins in this area. During the PHYCOB cruise in September 2021, two strains of one diatom and thirty strains of ten dinoflagellate species of potentially toxigenic plankton were characterized in terms of morphology, phylogeny, toxin profiles, and toxin cell quotas. Twenty strains of potentially yessotoxins (YTXs) producing dinoflagellate species were investigated. All six strains of <em>Protoceratium reticulatum</em> contained yessotoxin (YTX), with cell quotas between 1.9 and 5.4 pg cell^-1. Additionally, several YTX variants were detected in minor amounts in nine of twelve strains of <em>Lingulaulax polyedra</em>, whereas no YTXs were detected in two strains of other gonyaulacoids (<em>Gonyaulax</em> sp. and <em>Sourniaea diacantha</em>). All strains of <em>Alexandrium</em> spp. (four strains of <em>A. tamutum</em>, one strain each of <em>A. andersonii, A. ostenfeldii</em>, and <em>A. pseudogonyaulax</em>) were analyzed for all toxins known to be produced by the genus. None of the strains contained detectable levels of paralytic shellfish toxins (PSTs) or gymnodimines. <em>A. pseudogonyaulax</em> produced goniodomine A (GDA) and GDA-seco acid at cellular levels of 14.0 and 0.33 pg cell^-1, respectively. Moreover, four previously unreported spirolide analogues (SPX) were detected in the <em>A. ostenfeldii</em> strain, with cell quotas between 1.0 and 1.6 pg cell^-1. All strains of potentially ichthyotoxic species (<em>Karlodinium</em> sp., <em>Polykrikos hartmanii</em>) did not show extracellular lytic activity. In conclusion, these findings improve our understanding of the potential sources, diversity and dynamics of phycotoxins in the Black Sea.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"151 ","pages":"Article 103026"},"PeriodicalIF":4.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145688823","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":"RT-PCR assay development of ITS and toxin gene regions of, Aetokthonos hydrillicola, a known epiphyte of the invasive species Hydrilla verticillata","authors":"Theresa K. Hattenrath ,&nbsp;Erika Klar ,&nbsp;Katherine C. Callaghan ,&nbsp;Madelyn Caldwell ,&nbsp;Christopher Tucker ,&nbsp;Catherine A. McGlynn ,&nbsp;Susan B. Wilde","doi":"10.1016/j.hal.2025.103029","DOIUrl":"10.1016/j.hal.2025.103029","url":null,"abstract":"<div><div><em>Aetokthonos hydrillicola</em> is a toxic epiphytic cyanobacterium often associated with invasive water thyme (Hydrilla), <em>Hydrilla verticillata. A. hydrillicola</em> can produce a potent brominated neurotoxin, aetokthonotoxin (AETX), and a cytotoxic dolastatin analog, aetokthonostatin (AEST). The continued expansion of invasive Hydrilla across the United States, including New York State (NYS) waters, has highlighted the need for an accurate method to detect <em>A. hydrillicola</em> and its toxins due to the potential public health implications. A fast and accurate method for detecting <em>A. hydrillicola</em> and its toxins in aquatic plant materials was developed by targeting the rRNA ITS region (ITS1, ITS2) and biosynthetic gene clusters of AETX (aetxE, aetxA) and AEST (aestF, aestK). Samples from Southeastern United States and Southeastern NYS lakes and ponds were analyzed using the developed RT-PCR assays. Hydrilla from Lake Sebago tested positive for AEST genes, but was negative for both ITS and AETX genes, despite <em>A. hydrillicola</em> being confirmed via light microscopy. This is consistent with toxin analysis via LCMS finding no measurable AETX. The lack of AETX genes and the inability to amplify the Lake Sebago <em>A. hydrillicola</em> using current ITS primers/probes suggests that this is likely a different genetic variant. This data also suggests that AEST genes are likely conserved across genetic variants of <em>A. hydrillicola</em>. These RT-PCR assays will allow for an increased throughput of lakes surveyed for the presence of <em>A. hydrillicola</em> and its toxins, enabling environmental managers to make swift decisions regarding the prevention or reduction of impacts on wildlife and public health.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"151 ","pages":"Article 103029"},"PeriodicalIF":4.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577594","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":"2025-12-01","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":"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":"2025-12-01","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":"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":"2025-12-01","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 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":"2025-12-01","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":"Productivity, growth, and biogeochemistry of pelagic Sargassum in a changing world","authors":"Brian E. Lapointe,&nbsp;Deanna F. Webber,&nbsp;Rachel A. Brewton","doi":"10.1016/j.hal.2025.102940","DOIUrl":"10.1016/j.hal.2025.102940","url":null,"abstract":"<div><div>This review examines the changing distribution of pelagic <em>Sargassum</em> in the North Atlantic over the past four decades and how boundary current circulation enhances nutrient supply, productivity, and growth. Early explorers first described <em>Sargassum</em> in the Sargasso Sea and recognized the physical connectivity of “Gulfweed” to neritic populations in the Gulf of Mexico/America. In the 1980s, studies showed that <em>Sargassum</em> is more productive in neritic waters where it has lower carbon to nitrogen (C:N) and C to phosphorus (C:P) ratios. <em>Sargassum</em> productivity and growth are limited by both N and P, although P is often the primary limiting nutrient. The origin of the Great Atlantic <em>Sargassum</em> Belt (GASB) in 2011 was north the Amazon River mouth, suggesting this riverine nutrient source contributed to its development. This is supported by <em>Sargassum</em> tissue analysis and biomass increases/decreases between extreme flood/drought years in the Amazon basin. Comparison of the nutrient composition of <em>Sargassum</em> tissue (<em>n</em>= 849) from the 1980s with post-2010 and post-2020 showed increased %C (28 %), %N (55 % overall; 95 % in the Sargasso Sea), and N:P (50 %) but decreased %P (6 %) over the past four decades. Measurement of stable N isotopes (δ¹⁵N) in <em>Sargassum</em> revealed enriched δ¹⁵N correlated with increasing %N, pointing to the importance of terrestrial runoff, wastewater discharges, and coastal upwelling as potential N sources. We additionally report enriched levels of N and P in the western tropical region of the GASB, illustrating the importance of recent nutrient enrichment, especially P, to the excessive <em>Sargassum</em> biomass in the GASB.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"150 ","pages":"Article 102940"},"PeriodicalIF":4.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145047228","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}