Harmful Algae最新文献

{"title":"The toxin-producing diversity of Prorocentrum lima (Dinophyceae) populations of coastal China","authors":"Caihong Chen ,&nbsp;Jixing Peng ,&nbsp;Haoyu Zhang ,&nbsp;Guanchao Zheng ,&nbsp;Zhijun Tan ,&nbsp;Haiyan Wu","doi":"10.1016/j.hal.2025.102915","DOIUrl":"10.1016/j.hal.2025.102915","url":null,"abstract":"<div><div><em>Prorocentrum lima</em> (<em>P. lima)</em> is distributed in the four major seas of China. The diversity distribution of <em>P. lima</em> is confirmed by existing studies. The impact of this diversity feature on the difference of diarrhetic shellfish toxins (DSTs) components requires immediate investigation. Ten strains of <em>P. lima</em> were isolated from four major seas of China to explore the geographical differences in growth, toxicity production, and esterified composition. After 21 days of cultivation, strains isolated from the Bohai and Yellow China Sea (SHG and QD) exhibited slow growth and a maximum cell density of 3.3 × 10⁴ cells·mL^–1, whereas strains from the South China Sea (WZD and 3XS) demonstrated the highest growth rate and maximum algal density of 9.4 × 10⁴ cells·mL^–1. The total toxin content in single cells varied from 4.8 to 10.1 pg·cell^–1, with SHG and QD displaying the highest total toxin content at 10.1 pg·cell^–1. A total of 24 kinds of esterified components were identified across all ten strains of <em>P. lima</em>, comprising 43.9 %–92.2 % of total toxins, with the highest levels found in SHG and QD strains. Growth, toxicity production, and esterification of <em>P. lima</em>, taken from the four major sea areas of China, were significantly different. The contrasts in growth and toxicity potential revealed the existence of adaptive mechanisms of <em>P. lima</em> in different geographic environments, and the role of toxins in the adaptation mechanism requires further exploration.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"148 ","pages":"Article 102915"},"PeriodicalIF":5.5,"publicationDate":"2025-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144581039","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":"Physiological changes and gene expression in the mixotrophic haptophyte, Prymnesium parvum, respond to mixed nitrogen sources","authors":"Fengmiao Li ,&nbsp;Hailong Huang ,&nbsp;Qinfei Zhang ,&nbsp;Yun Shen ,&nbsp;Ningjian Luo ,&nbsp;Xinwei Wang ,&nbsp;Weizhong Chen ,&nbsp;Kaho Pak ,&nbsp;Jie Han ,&nbsp;Zhibing Jiang ,&nbsp;Chengxu Zhou ,&nbsp;Haibo Jiang","doi":"10.1016/j.hal.2025.102916","DOIUrl":"10.1016/j.hal.2025.102916","url":null,"abstract":"<div><div><em>Prymnesium parvum</em> is a toxin-producing haptophyte that adapts to various conditions in aquaculture wastewater, using strategies like allelopathy, toxicity, and predation to survive. However, knowledge about physiological and genetic responses of <em>P. parvum</em> to mixed nitrogen sources in aquaculture wastewater is still limited. Here, we cultured <em>P. parvum</em> in simulated aquaculture wastewater nitrogen composition, and revealed physiological and gene expression responses of <em>P. parvum</em> to mixed nitrogen sources. Under high concentrations mixed nitrogen sources (8.83 × 10³ μmol/L), <em>P. parvum</em> shows strong adaptability and competitiveness, predisposing it to harmful algal blooms (HABs) outbreaks. At low concentrations 8.83 × 10¹ μmol/L), it compensates by consuming other algae and producing toxins for defense. Transcriptomic data indicate that <em>P. parvum</em> upregulates nitrogen-related genes when transitioning from nitrate to mixed nitrogen, and downregulates them with increasing concentrations, significantly impacting glutamate metabolism and potentially enhancing direct ammonia conversion to <span>l</span>-glutamate, bypassing <span>l</span>-glutamine. Metabolic reprogramming in <em>P. parvum</em> may drive cell proliferation and HABs formation, with ecological consequences for aquaculture nitrogen dynamics.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"148 ","pages":"Article 102916"},"PeriodicalIF":5.5,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144548669","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":"High molecular diversity of potentially harmful heterotrophic dinophytes in tropical shrimp aquaculture ponds reveals a new dinophyte Malayana penaeicida gen. et sp. nov. (Peridiniales, Dinophyceae)","authors":"Siti Nursyuhada Baharudin ,&nbsp;Kieng Soon Hii ,&nbsp;Nur Fatihah Mohd Azmi ,&nbsp;Nur Syazwani Kassim ,&nbsp;Nursyahida Abdullah ,&nbsp;Sing Tung Teng ,&nbsp;Minlu Liu ,&nbsp;Koyo Kuwata ,&nbsp;Mitsunori Iwataki ,&nbsp;Haifeng Gu ,&nbsp;Po Teen Lim ,&nbsp;Chui Pin Leaw","doi":"10.1016/j.hal.2025.102906","DOIUrl":"10.1016/j.hal.2025.102906","url":null,"abstract":"<div><div>Shrimp aquaculture plays a pivotal role in global seafood production, particularly in Southeast Asia, where it significantly contributes to the economy and food security. The sustainability of this industry, however, is threatened by frequent mass mortality outbreaks with unknown causes. Despite the significant impact, there is a notable lack of information on the occurrence and diversity of harmful dinophytes in this system. This study, therefore, aimed to assess the diversity of potentially harmful dinophytes in shrimp ponds by utilizing advanced microscopy and high-throughput short- and long-read amplicon sequencing for metabarcoding. The metabarcoding results of 18S rDNA V7-V9 region revealed diverse dinophyte communities in the shrimp ponds, with compositions differing among ponds over the shrimp rearing period. While a variety of core dinophytes was detected, considerably high prevalence of harmful heterotrophic dinophytes, including <em>Pfiesteria piscicida, P. shumwayae, Luciella masanensis</em>, and <em>Gyrodinium jinhaense</em> were observed. Notably, a relatively high cell abundance of a peridinialean dinophyte, with cell densities that reached 10⁶ cells L⁻¹, was observed. The cells exhibited distinct thecal morphologies, corroborated by the concatenated phylogenetic tree of 18S–ITS–28S rDNA obtained from long-read sequencing and the 18S and 28S sequences from single-cell isolation, which herein assigned to a new genus <em>Malayana</em>, as <em>Malayana penaeicida</em> gen. <em>et</em> sp. nov.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"148 ","pages":"Article 102906"},"PeriodicalIF":4.5,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144860285","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":"Utilization of two types of dissolved organic phosphate by axenic and nonaxenic harmful Amphidinium carterae: Response of photosynthetic and hemolytic activity","authors":"Lianhong Tu ,&nbsp;Lingling Zhan ,&nbsp;Yu Gu ,&nbsp;Kehan Yi ,&nbsp;Mengmeng Tong","doi":"10.1016/j.hal.2025.102913","DOIUrl":"10.1016/j.hal.2025.102913","url":null,"abstract":"<div><div>Phosphorus (P) is a major limiting nutrient of phytoplankton in the current coastal ocean due to the overload of nitrogen; however, the dominance of the harmful dinoflagellate <em>Amphidinium carterae</em> has increased in the coastal ocean, leading to the hypothesis that <em>A. carterae</em> potentially utilizes dissolved organic phosphate (DOP)<em>.</em> Therefore, a series of experiments were conducted on axenic and nonaxenic <em>A. carterae</em> to investigate how dissolved inorganic phosphate (DIP) and two types of DOP (β-glycerol phosphate disodium salt hydrate (BGP) and 2-aminoethylphosphonic acid (2-AEP)) interact with the photosynthetic and hemolytic activities of <em>A. carterae</em>. The results showed that <em>A. carterae</em> could directly utilize BGP (C-O-P bonds of DOP) but had a limited ability to use 2-AEP (C-P bonds of DOP). A low amount of DIP (&lt;0.36 µM) reduced the growth, biomass, and photosynthetic activity of <em>A. carterae</em>; in contrast, it induced the hemolytic activity of <em>A. carterae</em>. However, the reduction in the hemolytic activity of <em>A. carterae</em> mostly relied on cell division rather than the utilization of DIP or DOP, as indicated by the significant negative relationship between the growth rate and hemolytic activity of <em>A. carterae</em>. The healthier the cells (high value of photosynthetic efficiency), the lower the hemolytic activity of <em>A. carterae</em>. Taken together, the ability to utilize the BGP makes it possible for <em>A. carterae</em> to become dominant in a BGP-sufficient environment, whereas the stress of cells, i.e., in P-limited conditions, may drive toxic events during blooms of <em>A. carterae</em>.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"148 ","pages":"Article 102913"},"PeriodicalIF":5.5,"publicationDate":"2025-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144501598","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":"Three-dimensional micro-mapping of microorganisms in the plastisphere using laser scanning confocal fluorescence microscopy","authors":"Aya Yamamoto Hoshihara ,&nbsp;Tetsuichi Fujiki ,&nbsp;Tetsuro Ikuta ,&nbsp;Shinji Shimode ,&nbsp;Youta Sugai ,&nbsp;Victor S. Kuwahara","doi":"10.1016/j.hal.2025.102914","DOIUrl":"10.1016/j.hal.2025.102914","url":null,"abstract":"<div><div>We investigated the attachment patterns of microorganisms within plastispheres on plastic surfaces through three-dimensional (3D) micro-mapping of the plastisphere using multichannel laser scanning confocal fluorescence microscopy (DNA staining, chlorophyll autofluorescence, exopolysaccharides staining, and reflection). This approach allowed us to focus on information derived from the 3D structures of the plastisphere. Four-channel observations of four types of plastics—polyethylene terephthalate (PET), polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), and polycarbonate (PC)—and glass plates immersed in coastal Sagami Bay for 10 days revealed the layered 3D structure of plastispheres composed mainly of diatoms and bacteria. Some dinoflagellates were also observed in the plastispheres. Morphological characteristics and chlorophyll content indicated that the observed dinoflagellates were in a vegetative form and included potentially toxic and/or red-tide-causing harmful dinoflagellates. This reaffirms previous concerns about environmental changes caused by toxic dinoflagellates captured on plastics and drifting in the ocean as hitchhikers, thereby spreading over a wider area than their original dispersion. Quantitative analysis of the 3D micro-mapped plastispheres suggested that a biofilm layer a few micrometers thick was required for dinoflagellates to attach to the plastic surface. Since extracellular polymeric substances (EPS) may be associated with the stickiness of the plastisphere, we performed five-channel observations, including exopolysaccharide staining to label EPS. These results suggested that the viscosity of EPS was responsible for these dinoflagellates’ attaching to plastic surfaces. These results provided a new perspective on the potential for the formation of plastispheres containing dinoflagellates.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"148 ","pages":"Article 102914"},"PeriodicalIF":5.5,"publicationDate":"2025-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144510738","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":"Deciphering nonlinear effects of climate and eutrophication synergies on Microcystis blooms using a causal inference framework","authors":"Jingkai Wang ,&nbsp;Mengqi He ,&nbsp;Min Pan ,&nbsp;Lirong Song ,&nbsp;Qichao Zhou ,&nbsp;Kun Shan","doi":"10.1016/j.hal.2025.102911","DOIUrl":"10.1016/j.hal.2025.102911","url":null,"abstract":"<div><div>Harmful cyanobacterial blooms (CyanoHABs) pose a significant threat to global water quality. Although eutrophication and climate change are recognized as key drivers of CyanoHABs proliferation, their synergistic effects remain elusive, hindering effective mitigation strategies. Here, we present a causal inference framework that leverages state-space reconstruction and empirical dynamic modeling to unravel the complex, nonlinear interactions governing CyanoHABs dynamics. Focusing on <em>Microcystis</em> blooms dynamics in Dianchi Lake (China), our approach uniquely integrates causal inference with time-series embedding, reconstructing the ecosystem’s hidden dynamics in a higher-dimensional geometric space. This foundation enables us to rigorously quantify causal drivers—such as nutrient loading and temperature—while overcoming the limitations of traditional correlation-based analyses. Our causal network analysis reveals distinct nonlinear responses of chlorophyll-<em>a</em> (Chl-<em>a</em>) concentration and <em>Microcystis</em> density to different nutrient drivers. Specifically, we found that in-lake total phosphorus (TP) exerts a stronger causal influence on overall algal dynamics than total nitrogen (TN). In contrast, external nutrient loading shows greater influence over <em>Microcystis</em> density compared to in-lake nutrients. Through scenario simulations, we further demonstrate that rising air temperatures amplify Chl-<em>a</em> concentration and <em>Microcystis</em> biomass through increased water temperatures, whereas precipitation-induced nutrient changes preferentially stimulate Chl-<em>a</em> production over <em>Microcystis</em> growth. Notably, we identified contrasting seasonal response patterns, with Chl-<em>a</em> exhibiting greater sensitivity to dry-season conditions while <em>Microcystis</em> density responded more strongly to wet-season drivers. By bridging mechanistic understanding and predictive modeling, our work offers a transformative tool for forecasting and managing CyanoHABs in changing climates.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"148 ","pages":"Article 102911"},"PeriodicalIF":5.5,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144501597","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":"Determinism of anatoxin-a production in Phormidium-dominated biofilms of a regulated river (Ain, France)","authors":"Charlotte Robichon ,&nbsp;Delphine Latour ,&nbsp;Fanny Perrière ,&nbsp;Sylvain Dolédec ,&nbsp;Joël Robin","doi":"10.1016/j.hal.2025.102912","DOIUrl":"10.1016/j.hal.2025.102912","url":null,"abstract":"<div><div>Benthic cyanobacteria have been increasingly held responsible for bird and mammal deaths along riverbanks in the last decades. However, little is known about the environmental conditions that favor their development, spatiotemporal dynamics and associated toxins. In the summer of 2020, we monitored physical, chemical and biological variables, quantified benthic cyanobacteria and measured anatoxin-a concentration in the biofilms of four reaches of the dam-regulated Ain River, France. The main potential anatoxin producer was <em>Phormidium</em>, often associated with <em>Oscillatoria</em> mats in the same field campaigns. Anatoxin-a detectable concentrations ranged from 0.5 to 197µg/g of dry weight showing a high spatial heterogeneity. According to structural equation modelling, anatoxin-a concentrations increased with water depth in a range of 20 to 80 cm. In contrast, the chlorophyta biovolume and the flow velocity were the main factors negatively correlated with anatoxin-a concentrations. Although flow velocity did not limit the biovolume of potential anatoxin producers, it could induce stress to the cyanobacterial mats within the river, causing a limitation of anatoxin-a concentrations. Finally, the effects of these drivers on anatoxin-a production demonstrated a high variability over the summer. This high temporal variability of both benthic cyanobacteria biomass and anatoxin-a concentration makes risk assessment relatively challenging.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"148 ","pages":"Article 102912"},"PeriodicalIF":5.5,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144517090","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":"Sailing together: A review of the pelagic Sargassum microbiome","authors":"D.D. Cox ,&nbsp;A.K. Stiffler ,&nbsp;V. Hervé ,&nbsp;M. Léger-Pigout ,&nbsp;L.C. Powers ,&nbsp;P.J. Lopez ,&nbsp;O.A. Sosa ,&nbsp;R.J. Parsons","doi":"10.1016/j.hal.2025.102904","DOIUrl":"10.1016/j.hal.2025.102904","url":null,"abstract":"<div><div>Pelagic <em>Sargassum</em>, denoting the two species <em>S. natans</em> and <em>S. fluitans</em>, has become a focal point of both scientific and public interest due to recent superbloom events. As a result, investigation into the dynamics of <em>Sargassum</em>-associated microbiota, which was previously quite limited, has regained momentum in the past five years. This review collates the current state of knowledge relating to the <em>Sargassum</em> microbiome as well as synthesizes relevant biogeochemical findings which may aid future efforts in this field. We explore microbiome composition and functional roles within this holobiont, specifically in terms of taxonomic diversity, macronutrient cycling, and the fate of <em>Sargassum</em>-derived organic matter. Despite progress, significant gaps remain in our understanding of the dynamic interactions within these microbial communities and their broader ecological significance. Future research directions are identified alongside recommendations for standardized protocols, emphasizing the need for more in-depth studies utilizing advanced molecular and biogeochemical techniques to unravel the full complexity of the <em>Sargassum</em> microbiome.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"148 ","pages":"Article 102904"},"PeriodicalIF":5.5,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144518941","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":"History, current status and future perspectives of sargassum management in the Eastern Caribbean SIDS: A story from the frontline","authors":"Kristie S.T. Alleyne ,&nbsp;Richéda Speede ,&nbsp;Hazel A. Oxenford ,&nbsp;Patrick McConney","doi":"10.1016/j.hal.2025.102910","DOIUrl":"10.1016/j.hal.2025.102910","url":null,"abstract":"<div><div>Mass influxes of pelagic <em>Sargassum</em> spp. in the Wider Caribbean region, since their inception in 2011, continue to present authorities with unprecedented management challenges relating to clean up, disposal and development of possible uses. To address these challenges, there have been many initiatives aimed at enhancing national capacity for the management of sargassum inundations and improving adaptation to influx events, and numerous technical and academic papers published on this topic. However, literature with specific relevance to the Eastern Caribbean Small Island Developing States (EC SIDS) is limited and somewhat fragmented. In this narrative review of the Eastern Caribbean sargassum management literature, together with our own knowledge and experience in this area, we examine the timeline of sargassum management, the current status of management, and highlight research and policy gaps that need to be addressed to improve management. In so doing we document how small island countries within the Eastern Caribbean have transitioned from simply reacting to sargassum influx events as a hazard, towards long-term adaptation and offer our perspectives on future management of sargassum in these SIDS. Throughout the years, the EC SIDS have excelled in knowledge dissemination, networking, research and securing some financial support, however, progress with implementation of management plans and improving institutional capacity has been comparatively slow. Advancing sustainable sargassum management in this region will require stronger governance, improved coordination, and sustained investment from both national governments and regional intergovernmental bodies. The key lessons from this review are likely to be highly relevant to other SIDS across the globe that are facing macroalgal blooms with similar resource and governance constraints.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"148 ","pages":"Article 102910"},"PeriodicalIF":5.5,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144306322","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":"Ocean acidification changes the interspecific competition of Sargassum fusiforme and Ulva lactuca by regulating carbon and nitrogen metabolism","authors":"Cong Cao ,&nbsp;Dongya Bao ,&nbsp;Lili Xu ,&nbsp;Zengling Ma ,&nbsp;Mingjiang Wu ,&nbsp;Guang Gao ,&nbsp;Kit Wayne Chew ,&nbsp;Shuaipeng Tian ,&nbsp;Binbin Chen","doi":"10.1016/j.hal.2025.102908","DOIUrl":"10.1016/j.hal.2025.102908","url":null,"abstract":"<div><div>Due to different response mechanisms of cultivated <em>Sargassum fusiforme</em> and its main epiphyte <em>Ulva lactuca</em> to ocean acidification caused by increased CO₂ concentrations, the effects of <em>U. lactuca</em> on its host may be different at elevated CO₂ concentrations. In this study, the effects of <em>U. lactuca</em> on the photosynthetic carbon assimilation process of <em>S. fusiforme</em> were studied under the condition of elevated CO₂ concentration. The results showed that co-culture with <em>U. lactuca</em> significantly inhibited the growth, photosynthesis and nitrogen metabolism of <em>S. fusiforme</em>, up-regulated the expression of its carbon assimilation-related genes such as antenna protein, phosphoglycerate kinase (PGK), ribulose-1,5-diphosphate carboxylase/oxygenase (RuBisCo), and down-regulated the expression of genes associated with growth and nitrogen metabolism. Under monoculture conditions, the growth and photosynthesis of <em>S. fusiforme</em> were significantly enhanced by elevated CO₂, and the expressions of photosynthetic carbon assimilation and antenna protein-related genes were up-regulated, reflecting the promotion of <em>S. fusiforme</em> photosynthesis. However, the enzyme activity and gene expression of nitrogen metabolism were inhibited. Under co-culture condition, the increase of CO₂ concentration also promoted the photosynthesis and growth of <em>S. fusiforme</em>, and up-regulated the expression of genes related to photosystem Ⅱ (PSⅡ) central proteins (including D1 and D2 proteins). The results of this study showed that <em>U. lactuca</em> inhibited the photosynthesis, growth and nitrogen metabolism of <em>S. fusiforme</em>, while ocean acidification promoted the photosynthesis of <em>S. fusiforme</em> by increasing activity of PSII, changing the carbon and nitrogen metabolism strategy, thus greatly alleviating the interspecific stress from its epiphyte <em>U. lactuca</em>. These results had important implications for exploring the ecological significance of seaweed farming and carbon sequestration efficiency in the context of future climate change.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"148 ","pages":"Article 102908"},"PeriodicalIF":5.5,"publicationDate":"2025-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144254428","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}