Harmful Algae最新文献

{"title":"An effective algaecide for the targeted destruction of Karenia brevis","authors":"Istiak Hossain ,&nbsp;Briana Mays ,&nbsp;Sydney L Hanhart ,&nbsp;John Hubble ,&nbsp;Pedram Azizihariri ,&nbsp;T.I. McLean ,&nbsp;Richard Pierce ,&nbsp;Vince Lovko ,&nbsp;Vijay T John","doi":"10.1016/j.hal.2024.102707","DOIUrl":"10.1016/j.hal.2024.102707","url":null,"abstract":"<div><p>We address the targeted destruction of <em>Karenia brevis</em> using the algaecide calcium peroxide, in tandem with the flocculation and sinking of the species. The specific aspect of the approach is the incorporation of the algaecide within the floc to rapidly kill <em>K. brevis</em>, thus minimizing escape of cells from the floc and reentry to the water column. CaO₂ gradually produces H₂O₂, which diffuses through cell membranes and induces oxidative stress, leading to cell death via excessive reactive oxygen species (ROS) formation. The effect of varying doses of calcium peroxide on <em>K. brevis</em> cells was measured with pulse amplitude modulated fluorometry and indicated that doses as low as 30 mg/L when integrated into flocs are effective in suppressing photosynthesis. Cell viability assays also indicate that such low levels are sufficient to cause cell death in a 3-6 hour time period. Thus, the proposed technology involving the incorporation of calcium peroxide in a cationic flocculating agent (polyaluminum chloride, PAC) leads to an inexpensive and scalable technology to mitigate harmful algal blooms of <em>K. brevis</em>.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102707"},"PeriodicalIF":5.5,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324001409/pdfft?md5=95ab6523ef548c8c89c66b465c436cc8&pid=1-s2.0-S1568988324001409-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142040689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The queen scallop Aequipecten opercularis: A slow domoic acid depurator?","authors":"José Luis García-Corona,&nbsp;Caroline Fabioux,&nbsp;Hélène Hégaret","doi":"10.1016/j.hal.2024.102708","DOIUrl":"10.1016/j.hal.2024.102708","url":null,"abstract":"<div><p>Domoic acid (DA) is a dangerous phycotoxin produced by several strains of diatoms of the genus <em>Pseudo-nitzschia,</em> and responsible for Amnesic Shellfish Poisoning (ASP) in humans. The increasingly intense ASP-outbreaks along the English Channel over the last three decades have forced persistent harvest closures of economically important and highly contaminated bivalve stocks exhibiting slow DA-depuration rates, like the king scallop <em>Pecten maximus</em>. Under this scenario, other pectinid species, such as the queen scallop <em>Aequipecten opercularis</em> have been empirically proposed as alternative resources to redress the high economic losses due to the banning of the exploitation of <em>P. maximus</em>. Nevertheless, the kinetics of DA depuration in <em>A. opercularis</em> have not been assessed so far, and its direct extraction after ASP-episodes could represent a serious threat to public health. Hence, the main objective of this work was to estimate the DA-depuration rate in the digestive gland (DG) of naturally contaminated scallops <em>A. opercularis</em> after a toxic <em>Pseudo-nitzschia australis</em> bloom subjected to experimental depuration in the laboratory for 30 days. This study also intended to go further in the knowledge about the anatomical distribution of DA in scallop tissues, and corroborate the implications of autophagy in DA-sequestration in the DG of this species as recently hypothesized. In the DG, the DA-depuration rate (0.018 day⁻¹) suggested that even with toxin burdens as low as 40 mg⋅kg⁻¹ in the DG, queen scallops may remain contaminated for about 70 days, thus longer under intensely contamination scenarios. The subcellular analyses corroborated DA-sequestration mainly through late-autophagy within residual bodies in the DG, without differences in the frequencies of anti-DA labeled residual bodies across the entire depuration process. These results revealed that <em>A. opercularis</em> cannot be considered a fast DA-depurator, and represent a baseline knowledge for decision-making about harvesting natural beds of queen scallops after toxic <em>Pseudo-nitzschia</em> blooms. The findings of this work also represent a cornerstone for further research to accelerate DA-depuration in this species.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102708"},"PeriodicalIF":5.5,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141964609","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":"Allelochemicals determine competition and grazing control in Alexandrium catenella","authors":"Stefanie D. Moorthi ,&nbsp;Michaela Busch ,&nbsp;Ulrike Feudel ,&nbsp;Urban Tillmann ,&nbsp;Bernd Krock ,&nbsp;Bob W. Kooi ,&nbsp;Jana Brinkmann ,&nbsp;Subhendu Chakraborty","doi":"10.1016/j.hal.2024.102704","DOIUrl":"10.1016/j.hal.2024.102704","url":null,"abstract":"<div><p>The production of allelochemicals by the toxigenic dinoflagellate <em>Alexandrium catenella</em> is one of the suggested mechanisms to facilitate its bloom formation and persistence by outcompeting other phototrophic protists and reducing grazing pressure. In Southern California, toxic events caused by <em>A. catenella</em> and paralytic shellfish toxins (PSTs) regularly impact coastal ecosystems; however, the trophic interactions and mechanisms promoting this species in a food web context are still not fully understood. In the present study, we combined a dynamical mathematical model with laboratory experiments to investigate potential toxic and allelochemical effects of an <em>A. catenella</em> strain isolated off the coast of Los Angeles, Southern California, on competitors and a common zooplankton consumer. Experiments were conducted using three toxigenic strains of <em>A. catenella</em>, comparing the new Californian isolate (Alex Cal) to two strains previously described from the North Sea, a lytic (Alex2) and non-lytic (Alex5) strain, testing for donor density-dependent effects on two phytoplankton species (<em>Rhodomonas salina, Tetraselmis</em> sp.) and on the rotifer <em>Brachionus plicatilis</em>. Bioassays revealed a steep decline in competitor and consumer populations with increasing Alex Cal concentrations, indicating an intermediate lytic activity compared to the North Sea strains (lytic Alex2 and non-lytic Alex5). The rotifer fed and grew well on the PST- toxic, but non-lytic Alex5 strain, while its survival significantly decreased with increasing concentrations of the two lytic strains Alex Cal and Alex 2, indicating that negative effects on the rotifer were mediated by allelochemicals rather than PST-toxins. Mixed culture experiments including both competitors and consumers demonstrated that the intensity of allelochemical effects not only depended on the <em>A. catenella</em> density but also on the target density. Negative effects on grazers were alleviated by co-occurring competitors with a lower sensitivity to allelochemicals, thus reducing harmful compounds and allowing grazing control on the dinoflagellate to come into effect again. Results from mixed culture experiments were supported by the mathematical approach used in this study which was calibrated with data from simple monoculture growth, pairwise competition and predator-prey experiments, demonstrating the applicability of this model approach to predict the outcome of more complex food web dynamics at the community level.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102704"},"PeriodicalIF":5.5,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324001379/pdfft?md5=ae622d24fdffe1176b6f0d883cee3929&pid=1-s2.0-S1568988324001379-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141952734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatiotemporal dynamics of 2-methylisoborneol produced by filamentous cyanobacteria and associated driving factors in Lake Taihu, China","authors":"Donghao Wu ,&nbsp;Mingxin Chen ,&nbsp;Aichun Shen ,&nbsp;Yadong Shi","doi":"10.1016/j.hal.2024.102703","DOIUrl":"10.1016/j.hal.2024.102703","url":null,"abstract":"<div><p>The proliferation of filamentous cyanobacteria in lakes can result in the generation of odor-causing compounds, predominantly 2-methylisoborneol (2-MIB), which pose odor-related challenges. In an effort to elucidate the spatiotemporal dynamics of 2-MIB and related influencing factors in East Lake Taihu, monthly investigations were undertaken from April 2022 to March 2023. In addition to the monthly survey, a whole-lake survey was conducted during the high-temperature period from July to September. The monthly survey revealed a distinct unimodal fluctuation in the concentration of 2-MIB in East Lake Taihu, with an average concentration at 297.0 ng/L during the high-temperature period. During the high-temperature period, the filamentous cyanobacterial communities detected in East Lake Taihu consisted primarily of species belonging to genera <em>Leptolyngbya, Oscillatoria, Planktothricoides</em>, and <em>Pseudanabaena</em>. However, no significant correlations were found between their densities and 2-MIB concentration. In addition, the <em>mic</em> gene was predominantly detected in genera <em>Pseudanabaena</em> and <em>Planktothricoides</em>, with the latter being the primary contributor to 2-MIB production. Furthermore, a succession of cyanobacteria capable of producing 2-MIB was detected, with water temperature and radiation intensity being identified as the primary driving factors. The temporal variation of 2-MIB concentration within East Lake Taihu during the whole year was primarily modulated by factors such as water temperature, water transparency, dissolved oxygen, and chlorophyll-<em>a</em>. During the high-temperature period, the 2-MIB concentration in the alga-dominated zone of East Lake Taihu was approximately 1.7 times greater than that in the macrophyte-dominated zone, with nutrient and transparency being identified as the main influencing factors. Consequently, our findings are of great significance for monitoring the sources and variation of 2-MIB in shallow lakes, providing a scientific foundation and theoretical guidance for odor management.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102703"},"PeriodicalIF":5.5,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141932446","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":"Image-derived indicators of phytoplankton community responses to Pseudo-nitzschia blooms","authors":"Vitul Agarwal ,&nbsp;Virginie Sonnet ,&nbsp;Keisuke Inomura ,&nbsp;Audrey B. Ciochetto ,&nbsp;Colleen B. Mouw","doi":"10.1016/j.hal.2024.102702","DOIUrl":"10.1016/j.hal.2024.102702","url":null,"abstract":"<div><p>Phytoplankton populations in the natural environment interact with each other. Despite rising global concern with <em>Pseudo-nitzschia</em> blooms, which can produce the potent neurotoxin domoic acid, we still do not fully understand how other phytoplankton genera respond to the presence of <em>Pseudo-nitzschia</em>. Here, we used a 4-year high-resolution imaging dataset for 9 commonly found phytoplankton genera in Narragansett Bay, alongside environmental data, to identify potential interactions between phytoplankton genera and their response to elevated <em>Pseudo-nitzschia</em> abundance. Our results indicate that <em>Pseudo-nitzschia</em> tends to bloom either concurrently with or right after other phytoplankton genera. Such bloom periods coincide with higher water temperatures and lower salinity. <em>Pseudo-nitzschia</em> image abundance tends to increase the most from March-May and peaks during May-Jun, whereas the image-derived biovolume and width of <em>Pseudo-nitzschia</em> chains increase the most during Jan-Feb. For most phytoplankton genera, their relationship with <em>Pseudo-nitzschia</em> abundance is noticeably different from their relationship with <em>Pseudo-nitzschia</em> image features. Despite the complexity in the phytoplankton community, our analysis suggests several ecological indicators that may be used to determine the risk of harmful algal blooms.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102702"},"PeriodicalIF":5.5,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324001355/pdfft?md5=30ce5f6a2c1693a1687275ae8752ac2d&pid=1-s2.0-S1568988324001355-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141964607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phylogeny and ultrastructure of a non-toxigenic dinoflagellate Amphidoma fulgens sp. nov. (Amphidomataceae, Dinophyceae), with a wide distribution across Asian Pacific","authors":"Koyo Kuwata ,&nbsp;Wai Mun Lum ,&nbsp;Kazuya Takahashi ,&nbsp;Garry Benico ,&nbsp;Kazutaka Takahashi ,&nbsp;Po Teen Lim ,&nbsp;Chui Pin Leaw ,&nbsp;Hajime Uchida ,&nbsp;Mayu Ozawa ,&nbsp;Ryoji Matsushima ,&nbsp;Ryuichi Watanabe ,&nbsp;Toshiyuki Suzuki ,&nbsp;Mitsunori Iwataki","doi":"10.1016/j.hal.2024.102701","DOIUrl":"10.1016/j.hal.2024.102701","url":null,"abstract":"<div><p><em>Amphidoma languida</em>, a marine thecate dinoflagellate that produces the lipophilic toxin azaspiracids (AZAs), is primarily found in the Atlantic. Although this species has not been recorded in the Asian Pacific, environmental DNAs related to <em>Am. languida</em> have been widely detected in the region by metabarcoding analysis. Their morphology and AZA production remain unclear. In this study, the morphology, ultrastructure, phylogeny, and AZA production of nine <em>Amphidoma</em> strains isolated from Japan, Malaysia, and Philippines were investigated. Phylogenetic trees inferred from rDNAs (SSU, ITS, and LSU rDNA) showed monophyly of the nine Pacific strains and were sister to the <em>Am. languida</em> clade, including the toxigenic strains from the Atlantic. Cells were ellipsoid, 8.7–16.7 µm in length and 7.4–14.0 µm in width, with a conspicuous apical pore complex. A large nucleus in the hyposome, parietal chloroplast with a spherical pyrenoid in the episome, and refractile bodies were observed. Thecal tabulation was typical of <em>Amphidoma</em>, Po, cp, X, 6ʹ, 6ʹʹ, 6C, 5S, 6ʹʹʹ, 2ʹʹʹʹ. A ventral pore was located on the anterior of 1ʹ plate, beside the suture to 6ʹ plate. The presence of a ventral depression, on the anterior of anterior sulcal plate, was different from <em>Am. languida</em>. A large antapical pore, containing approximately 10 small pores, was observed. Cells were apparently smaller than <em>Am. trioculata</em>, a species possessing three pores (ventral pore, ventral depression, and antapical pore). TEM showed the presence of crystalline structures, resembling guanine crystals, and cytoplasmic invaginations into the pyrenoid matrix. Flagellar apparatus lacking the striated root connective is similar to peridinioids and related dinoflagellates. AZAs were not detected from the Pacific strains by LC-MS/MS. This non-toxigenic <em>Amphidoma</em> species, here we propose as <em>Amphidoma fulgens</em> sp. nov., is widely distributed in the Asian Pacific. Moreover, molecular comparison also suggested that most of the environmental DNA sequences previously reported as <em>Am. languida</em> or related sequences from the Asian Pacific were attributable to <em>Am. fulgens</em>.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102701"},"PeriodicalIF":5.5,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324001343/pdfft?md5=68c1354d5d3a3d7a2e7ffa30c042888e&pid=1-s2.0-S1568988324001343-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141848490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long-term changes in spatiotemporal distribution of Noctiluca scintillans in the southern North Sea","authors":"Katharina Kordubel ,&nbsp;Raúl O. Martínez-Rincón ,&nbsp;Burkard Baschek ,&nbsp;Maarten Boersma ,&nbsp;Martin Hieronymi ,&nbsp;David G. Johns ,&nbsp;Inga V. Kirstein ,&nbsp;Yoana G. Voynova ,&nbsp;Klas O. Möller","doi":"10.1016/j.hal.2024.102699","DOIUrl":"10.1016/j.hal.2024.102699","url":null,"abstract":"<div><p>To assess the spatiotemporal evolution of the heterotrophic dinoflagellate <em>Noctiluca scintillans</em> in the North Sea, the Helgoland Roads time series and Continuous Plankton Recorder survey were analysed using generalized additive models. Over the last decades, blooms of <em>N. scintillans</em> have occurred more frequently and intensively in many regions. This harmful algal bloom forming species can alter food webs, reduce ecosystem productivity, and lead to economic losses while causing lower aquacultural yields. After the 1990s, <em>N. scintillans</em> abundances have significantly increased by 1.65-fold and a significant prolongation of the bloom window was found (from 27.5 to 98 days in recent decades) off the island of Helgoland, Germany. Significant correlations were found between bloom initiation and nutrients, as well as light availability since these factors lead to increased prey availability. Highest abundances of <em>N. scintillans</em> were associated with water temperatures around 17 °C and wind speed below 6 ms⁻¹ causing dense surface accumulations. Solar radiation of more than 200 Wm⁻² was identified as a main driver for post-bloom conditions as it can deteriorate the cells and lead to the decline of <em>N. scintillans</em> abundances. In the southern North Sea, <em>N. scintillans</em> occurrences have intensified and spread since the 1980s with hotspots identified as the coastal waters adjacent to the estuaries of the Elbe and Rhine rivers.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102699"},"PeriodicalIF":5.5,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S156898832400132X/pdfft?md5=12b2081d230f3ba89ca3a5b2fd6b70d4&pid=1-s2.0-S156898832400132X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141781746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Co-occurrence between key HAB species and particle-attached bacteria and substrate specificity of attached bacteria in the coastal ecosystem","authors":"Hyun-Jung Kim ,&nbsp;Yu Jin Kim ,&nbsp;Donhyug Kang ,&nbsp;Hansoo Kim ,&nbsp;Sungho Cho ,&nbsp;Taek-Kyun Lee ,&nbsp;Sang Heon Lee ,&nbsp;Seung Won Jung ,&nbsp;Junsu Kang","doi":"10.1016/j.hal.2024.102700","DOIUrl":"10.1016/j.hal.2024.102700","url":null,"abstract":"<div><p>The ecological dynamics of particle-attached bacteria (PAB) were observed through changes in the core phytoplankton phycosphere, and were associated with the dynamics of free-living bacteria (FLB) using metabarcoding and microscopic analyses over 210 days (with weekly sampling intervals) in the Jangmok coastal ecosystem, South Korea. Cluster analysis and non-metric multidimensional scaling classified the phytoplankton community into six groups comprising core phytoplankton species, including the harmful algal species <em>Akashiwo sanguinea</em> (dinoflagellate) in late autumn, <em>Teleaulax amphioxeia</em> (cryptomonads) in early winter and spring, <em>Skeletonema marinoi-dohrnii</em> complex (diatom) in winter, <em>Pseudo-nitzschia delicatissima</em> (diatom) in early spring, and diatom complexes such as <em>Chaetoceros curvisetus</em> and <em>Leptocylindrus danicus</em> in late spring. We identified 59 and 32 indicators in PAB and FLB, respectively, which rapidly changed with the succession of the six core phytoplankton species. The characteristics of PAB were mainly divided into “Random encounters” or “Attraction of motivation by chemotaxis.” When <em>Akashiwo sanguinea</em> bloomed, bacteria of the genera <em>Kordiimonas</em> and <em>Polaribacter</em>, which are commonly observed in PAB and FLB, indicated “Random encounter” characteristics. In addition, <em>Sedimenticola</em> of PAB was uniquely presented in <em>Akashiwo sanguinea</em>, exhibiting characteristics of “Attraction of motivation by chemotaxis.” In contrast, FLB followed the strategy of “Random encounters” because it was not affected by specific habitats and energy sources. Thus, many common bacteria were PAB and FLB, thereby dictating the bacteria's strategy of “Random encounters.” “Attraction of motivation by chemotaxis” has characteristics of the species-specific interactions between PAB and specific harmful algal species, and is potentially influenced by organic matter of core phytoplankton cell surface and/or EPS released from phytoplankton.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102700"},"PeriodicalIF":5.5,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141845056","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 novel strategy of bloom forming cyanobacteria Microcystis sp. in response to phosphorus deficiency: Using non-phosphorus lipids substitute phospholipids","authors":"Zhenghan Liu ,&nbsp;Lingling Wan ,&nbsp;Jingjie Zhang ,&nbsp;Dong Bai ,&nbsp;Chunlei Song ,&nbsp;Yiyong Zhou ,&nbsp;Hong Shen ,&nbsp;Xiuyun Cao","doi":"10.1016/j.hal.2024.102694","DOIUrl":"10.1016/j.hal.2024.102694","url":null,"abstract":"<div><p>Despite significant reductions in phosphorus (P) loads, lakes still experience cyanobacterial blooms. Little is known regarding cellular P regulation in response to P deficiency in widely distributed bloom causing species such as <em>Microcystis</em>. In this study, we investigated changes in P containing and non-P lipids contents and their ratios concomitantly with the determinations of expression levels of genes encoding these lipids in cultural and field <em>Microcystis</em> samples. In the culture, the content of phosphatidylglycerol (PG) decreased from 2.1 μg g^-1 in P replete control to 1.2 μg g^-1 in P-deficient treatment, while non-P lipids, like sulfoquinovosyldiacylglycerol (SQDG) and monogalactosyldiacylglycerol (MGDG), increased dramatically from 13.6 μg g^-1 to 142.3 μg g^-1, and from 0.9 μg g^-1 to 16.74 μg g^-1, respectively. The expression of the MGDG synthesis gene, <em>mgd</em>E, also increased under low P conditions. Significant positive relationships between soluble reactive phosphorus (SRP) and ratios of P-containing lipids (PG) to non-P lipids, including SQDG, MGDG and digalactosyldiacylglycerol (DGDG) (<em>P</em> &lt; 0.05) were observed in the field investigations. Both cultural and field data indicated that <em>Microcystis</em> sp. might increase non-P lipids proportion to lower P demand when suffering from P deficiency. Furthermore, despite lipid remodeling, photosynthetic activity remained stable, as indicated by comparable chlorophyll fluorescence and <em>Fv/Fm</em> ratios among cultural treatments. These findings suggested that <em>Microcystis</em> sp. may dominate in P-limited environments by substituting glycolipids and sulfolipids for phospholipids to reduce P demand without compromising the photosynthetic activity. This effective strategy in response to P deficiency meant a stricter P reduction threshold is needed in terms of <em>Microcystis</em> bloom control.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102694"},"PeriodicalIF":5.5,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141702411","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":"Determining ecological interactions of key dinoflagellate species using an intensive metabarcoding approach in a semi-closed coastal ecosystem of South Korea","authors":"Yu Jin Kim ,&nbsp;Hyun-Jung Kim ,&nbsp;Taek-Kyun Lee ,&nbsp;Donhyug Kang ,&nbsp;Hansoo Kim ,&nbsp;Sungho Cho ,&nbsp;Jin Ho Kim ,&nbsp;Seung Won Jung","doi":"10.1016/j.hal.2024.102698","DOIUrl":"10.1016/j.hal.2024.102698","url":null,"abstract":"<div><p>Marine phytoplankton communities are pivotal in biogeochemical cycles and impact global climate change. However, the dynamics of the dinoflagellate community, its co-occurrence relationship with other eukaryotic plankton communities, and environmental factors remain poorly understood. In this study, we aimed to analyze the temporal changes in the eukaryotic plankton community using a 18S rDNA metabarcoding approach. We performed intensive monitoring for 439 days at intervals of three days during the period from November 2018 to June 2020 (<em>n</em> = 260) in Jangmok Bay Time-series Monitoring Site in South Korea. Among the 16,224 amplicon sequence variants (ASVs) obtained, dinoflagellates were the most abundant in the plankton community (38 % of total relative abundance). The dinoflagellate community was divided into 21 groups via cluster analysis, which showed an annually similar distribution of low-temperature periods. Additionally, we selected 11 taxa that had an occurrence mean exceeding 1 % of the total dinoflagellate abundance, accounting for 93 % of the total dinoflagellate community: namely <em>Heterocapsa rotundata, Gymnodinium</em> sp., <em>Akashiwo sanguinea, Amoebophrya</em> sp., <em>Euduboscquella</em> sp., <em>Spiniferites ramosus, Dissodinium pseudolunula, Sinophysis</em> sp., <em>Karlodinium veneficum</em>, and <em>Katodinium glaucum</em>. The key dinoflagellate species were well represented at temporally variable levels over an entire year. <em>Heterocapsa rotundata</em> was not significantly affected by water temperature, whereas its dynamics were largely influenced by strong predation pressure, competition, and/or the supplementation of food sources. The growth of <em>A. sanguinea</em> was associated with dissolved inorganic phosphorus concentrations, while <em>Euduboscquella</em> sp. showed a significant relationship with <em>D. pseudolunula</em> and <em>K. glaucum</em>, largely representing a positive association that implies possible parasitic mechanisms. This study demonstrated interactions between key dinoflagellate species and the environment, as well as parasites, predators, competitors, and feeders.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102698"},"PeriodicalIF":5.5,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141696705","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}