Harmful Algae最新文献

{"title":"Diversity, toxicity, and distribution of potentially toxic diatoms in Antarctic waters––With description of Pseudo-nitzschia meridionalis sp. nov. and P. glacialis sp. nov.","authors":"Nina Lundholm ,&nbsp;Anneliese L. Christensen ,&nbsp;Anna K.J. Olesen ,&nbsp;Bánk Beszteri ,&nbsp;Sarah Lena Eggers ,&nbsp;Bernd Krock ,&nbsp;Andreas Altenburger","doi":"10.1016/j.hal.2024.102724","DOIUrl":"10.1016/j.hal.2024.102724","url":null,"abstract":"<div><div>Diatoms of the genus <em>Pseudo-nitzschia</em>, known for their potential toxicity, are integral to the phytoplankton community of the Southern Ocean, which surrounds Antarctica. Despite their ecological importance, the diversity and toxicity of <em>Pseudo-nitzschia</em> in this region remain underexplored. Globally, these diatoms are notorious for forming harmful algal blooms in temperate and tropical waters, causing significant impacts on marine life, ecosystems, and coastal economies. However, detailed information on the diversity, morphology, and toxicity of <em>Pseudo-nitzschia</em> species in Antarctic waters is limited, with molecular characterizations of these species being particularly scarce.</div><div>During three research expeditions to the Southern Ocean, monoclonal strains of <em>Pseudo-nitzschia</em> were isolated and cultivated. Stored samples from a fourth expedition, the Brategg expedition, were used to complete the description of particularly <em>P. turgidula</em>. Through electron microscopy and molecular analysis, two novel species were identified—<em>Pseudo-nitzschia meridionalis</em> sp. nov. and <em>Pseudo-nitzschia glacialis</em> sp. nov.—alongside the previously described species <em>P. subcurvata, P. turgiduloides</em>, and <em>P. turgidula</em>. Toxin assays revealed no detectable levels of domoic acid in <em>P. turgiduloides, P. turgidula, P. meridionalis</em> sp. nov. and <em>P. glacialis</em> sp. nov. Conversely, <em>P. subcurvata</em> was reported in a related study to produce domoic acid and its isomer, isodomoic acid C.</div><div>These findings emphasize the need for comprehensive research on the phytoplankton of Antarctic waters, which is currently a largely uncharted domain. With the looming threat of climate change, understanding the dynamics of potentially harmful algal populations in this region is becoming increasingly critical.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"139 ","pages":"Article 102724"},"PeriodicalIF":5.5,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324001574/pdfft?md5=7e59ef19d51e6398fbe85782b7c1ad4b&pid=1-s2.0-S1568988324001574-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142312680","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":"Enhanced eDNA monitoring for detection of viable harmful algal bloom species using propidium monoazide","authors":"Kun-woo Yun,&nbsp;Hwa-seong Son,&nbsp;Min-jun Seong,&nbsp;Seung-min Lee,&nbsp;Mu-chan Kim","doi":"10.1016/j.hal.2024.102725","DOIUrl":"10.1016/j.hal.2024.102725","url":null,"abstract":"<div><p>This study investigated the use of propidium monoazide (PMA) to improve the accuracy of environmental DNA (eDNA) monitoring by selectively detecting intracellular DNA (iDNA) from living cells, while excluding extracellular DNA (exDNA) from dead organisms. eDNA samples were collected from various depths off the coast of Tongyeong, South Korea, and analyzed alongside environmental factors, such as temperature, dissolved oxygen, turbidity, and nutrient levels. The results showed that PMA-treated iDNA provided a more accurate estimate of viable harmful algal bloom species (HABs) than total eDNA and DNase-treated iDNA. Strong correlations were found between iDNA (PMA) and environmental factors, particularly nutrient levels and turbidity, suggesting its effectiveness in biological environments. The iDNA (PMA) concentrations were higher in the surface and bottom layers, indicating that these layers were more indicative of living organisms in marine environments. The application of PMA in eDNA monitoring reduces false positives and enhances the detection accuracy of viable HAB species, representing a promising tool for real-time monitoring and management of marine ecosystems.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"139 ","pages":"Article 102725"},"PeriodicalIF":5.5,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142232184","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":"Intracellular abundance, localization, and enzymatic activity of a saxitoxin biosynthesis enzyme, SxtG, in two sister subclones of the dinoflagellate Alexandrium catenella with extremely different levels of paralytic shellfish toxins","authors":"Yuko Cho ,&nbsp;Shizu Hidema ,&nbsp;Takuo Omura ,&nbsp;Shigeki Tsuchiya ,&nbsp;Keiichi Konoki ,&nbsp;Yasukatsu Oshima ,&nbsp;Mari Yotsu-Yamashita","doi":"10.1016/j.hal.2024.102723","DOIUrl":"10.1016/j.hal.2024.102723","url":null,"abstract":"<div><p>Paralytic shellfish poisoning is caused by saxitoxin (STX), and its analogues (paralytic shellfish toxins (PSTs)) produced by marine dinoflagellates. SxtA and SxtG are the most essential enzymes in STX biosynthesis. Previous studies investigated the abundance and subcellular localization (<em>i.e.</em>, chloroplasts) of SxtA in dinoflagellates using immunostaining. The present study characterized SxtG, and positive signals were detected in sister subclones of <em>Alexandrium catenella</em> (Group I) with extremely different levels of PSTs. Multiplex fluorescence immunostaining detection of a PST-positive subclone revealed co-localization of SxtA and SxtG, suggesting that SxtG localizes to chloroplasts. <em>In vitro</em> amidino-transfer from arginine to Int-A’, the first intermediate product in the biosynthesis, was presumed to be catalyzed by SxtG, and the reaction was established using crude extracts of PST-positive and negative <em>A. catenella</em> subclones. These analyses suggested that the PST-negative subclone expresses active SxtG but not SxtA. These findings support our hypothesis that decrease of SxtA leads to the loss of toxicity in the PST-negative subclone of <em>A. catenella</em>. Our results identified a key reaction that could enhance understanding of the biochemistry of STX biosynthesis in dinoflagellates.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"139 ","pages":"Article 102723"},"PeriodicalIF":5.5,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324001562/pdfft?md5=fee179787431db79717ed90aee60f386&pid=1-s2.0-S1568988324001562-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142239857","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":"Temperature-dependent akinete formation strategies of the harmful cyanobacterium Dolichospermum circinale","authors":"Chae-Hong Park ,&nbsp;Dae-Ryul Kwon ,&nbsp;Keonhee Kim ,&nbsp;Youn-Bo Sim ,&nbsp;Soon-Jin Hwang","doi":"10.1016/j.hal.2024.102722","DOIUrl":"10.1016/j.hal.2024.102722","url":null,"abstract":"<div><p>Cyanobacteria from the orders Nostocales and certain Stigonematales form akinetes, spore-like dormant cells that allow them to survive adverse environmental conditions. Temperature is known to be one of the key factors affecting akinete formation, but there is currently little known about akinete formation during cell growth over a wide range of temperature conditions and its relation to the overall survival strategy of cyanobacteria. Therefore, in the current study, we conducted a temperature-controlled experiment to analyze the akinete formation of a harmful cyanobacterium <em>Dolichospurmum circinale</em> using a growth chamber. We measured the concentration and size of both vegetative cells and different types of akinetes (free, attached, and empty type) under varying temperatures (5–25 °C). We also analyzed the buoyant ability and vertical migration velocity of trichomes along with changes in the volume of vegetative cells and akinetes. The total akinete concentration and ratio (number of akinetes to total number of cells) were both found to be higher at high temperatures (20–25°C) than they were at low temperatures (5–10°C) (p&lt;0.05). Meanwhile, the rate of formation of akinetes (both free and attached akinetes) was highest at low temperature (10 °C) and decreased with increasing temperature. The rate of empty akinete formation increased with increasing temperature and was highest at 25°C, indicating that most of the akinetes produced under high temperature conditions germinated. The change in vegetative cell size was proportional to the increase in the growth rate in response to increasing temperature (p&lt;0.05). At high temperature, vegetative cells exhibited positive buoyancy and higher vertical migration velocity, while at low temperature, they exhibited negative buoyancy and relatively low migration velocity. Akinete size was larger at low temperature than it was at high temperature. These findings suggest that akinetes play an important role in maintaining populations in the water column, with a link between akinete formation and germination during summer cyanobacteria blooms. This information is expected to contribute to a deeper understanding of the <em>D. circinale</em> life cycle.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"139 ","pages":"Article 102722"},"PeriodicalIF":5.5,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324001550/pdfft?md5=750f603cbc5db879adfb904424002aef&pid=1-s2.0-S1568988324001550-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142164739","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 green convergence: United States lakes are collectively moving toward a eutrophic state","authors":"Edna G. Fernandez-Figueroa ,&nbsp;Stephanie R. Rogers ,&nbsp;Matthew N. Waters ,&nbsp;Alan E. Wilson","doi":"10.1016/j.hal.2024.102721","DOIUrl":"10.1016/j.hal.2024.102721","url":null,"abstract":"<div><p>Nutrient enrichment and climate change promote algal blooms, leading to many lakes being characterized as eutrophic (i.e., green) worldwide. We examined recent eutrophication trends of freshwater lakes at a national scale by collating 32 years (1990–2021) of growing season (July-September) <em>in situ</em> chlorophyll-<em>a</em>, nutrient, transparency, and climate data for 1,082 lakes across 32 freshwater ecoregions in the United States. Based on chlorophyll-<em>a</em>, 78.2 % (427/546) of lakes initially exhibited eutrophic conditions and have remained eutrophic. Moreover, non-eutrophic lakes converged toward a eutrophic state, with oligotrophic (i.e., clear) or mesotrophic (i.e., moderately clear) lakes becoming greener, and hypereutrophic (i.e., very green) becoming less green. Optimized Hot Spot Analysis suggests lakes in the Appalachian Piedmont and Apalachicola freshwater ecoregions eutrophied more rapidly than other locations. Results suggest nutrient management targeting eutrophic lakes has hindered further degradation, but poor preventative management of clear lakes has led to their eutrophication.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"139 ","pages":"Article 102721"},"PeriodicalIF":5.5,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324001549/pdfft?md5=c9f590cbb4747410140f7230d0b5becb&pid=1-s2.0-S1568988324001549-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142228856","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":"Toxic effects of the emerging Alexandrium pseudogonyaulax (Dinophyceae) on multiple trophic levels of the pelagic food web","authors":"Kristof Möller ,&nbsp;Urban Tillmann ,&nbsp;Magdalena Pöchhacker ,&nbsp;Elisabeth Varga ,&nbsp;Bernd Krock ,&nbsp;Francesco Porreca ,&nbsp;Florian Koch ,&nbsp;Thomas M. Harris ,&nbsp;Cédric L. Meunier","doi":"10.1016/j.hal.2024.102705","DOIUrl":"10.1016/j.hal.2024.102705","url":null,"abstract":"<div><p>The dinoflagellate <em>Alexandrium pseudogonyaulax</em>, a harmful algal bloom species, is currently appearing in increasing frequency and abundance across Northern European waters, displacing other <em>Alexandrium</em> species. This mixotrophic alga produces goniodomins (GDs) and bioactive extracellular substances (BECs) that may pose a threat to coastal ecosystems and other marine resources. This study demonstrated the adverse effects of <em>A. pseudogonyaulax</em> on four marine trophic levels, including microalgae (<em>Rhodomonas salina</em>), microzooplankton (<em>Polykrikos kofoidii</em>) and mesozooplankton (<em>Acartia tonsa</em>), as well as fish gill cells (RTgill-W1, <em>Oncorhynchus mykiss</em>), ultimately leading to enhanced mortality and cell lysis. Furthermore, cell-free supernatants collected from <em>A. pseudogonyaulax</em> cultures caused complete loss of metabolic activity in the RTgill-W1 cell line, indicating ichthyotoxic properties, while all tested GDs were much less toxic. In addition, cell-free supernatants of <em>A. pseudogonyaulax</em> led to cell lysis of <em>R. salina</em>, while all tested GDs were non-lytic. Finally, reduced egg hatching rates of <em>A. tonsa</em> eggs exposed to cell-free supernatants of <em>A. pseudogonyaulax</em> and impaired mobility of <em>P. kofoidii</em> and <em>A. tonsa</em> exposed to <em>A. pseudogonyaulax</em> were also observed. Altogether, bioassay results suggest that the toxicity of <em>A. pseudogonyaulax</em> is mainly driven by BECs and not by GDs, although further research into factors modulating the lytic activity of <em>Alexandrium</em> spp. are needed.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"138 ","pages":"Article 102705"},"PeriodicalIF":5.5,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324001380/pdfft?md5=09b15ebc00116d8ada14edbd05d929d9&pid=1-s2.0-S1568988324001380-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142098057","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":"Nutrient availability in a freshwater-to-marine continuum: Cyanobacterial blooms along the Lake Okeechobee Waterway","authors":"Brian E. Lapointe,&nbsp;Rachel A. Brewton,&nbsp;Malcolm N. McFarland,&nbsp;Nicole Stockley","doi":"10.1016/j.hal.2024.102710","DOIUrl":"10.1016/j.hal.2024.102710","url":null,"abstract":"<div><p>Water from the Lake Okeechobee watershed historically flowed south through the Everglades. Hydrologic alterations created the Lake Okeechobee Waterway, where lake water is periodically shunted east to the St. Lucie Estuary (C-44 canal) and west to the Caloosahatchee River and Estuary (C-43 canal). Within the last two decades, <em>Microcystis</em> blooms have developed in Lake Okeechobee and been discharged to the downstream urbanized estuaries, resulting in negative environmental and human health impacts. To better understand drivers of cyanobacterial blooms across this modified waterway, two cruises were conducted from the St. Lucie Estuary through Lake Okeechobee to the Caloosahatchee River Estuary during 2019 and 2020. Opportunistic sampling was also conducted during <em>Microcystsis</em> blooms. Cruise stations were sampled for environmental parameters, dissolved nutrients, chlorophyll <em>a</em>, cyanobacterial cell concentrations, and microcystins, as well as particulate organic matter (POM) nutrient properties. Higher ammonium (NH₄⁺), nitrate + nitrite (NO₃^-), dissolved inorganic nitrogen (DIN), soluble reactive phosphorus (SRP), total dissolved phosphorus (TDP), and POM stable N isotope (δ¹⁵N) values were observed in the estuaries and Kissimmee River than in Lake Okeechobee. The nitrogen to phosphorus ratio (N:P), microcystins, and <em>Microcystis</em> cell concentrations were higher in Lake Okeechobee than documented over past decades. During <em>Microcystis</em> blooms, high NH₄⁺, SRP, total dissolved nitrogen (TDN), TDP, and sucralose were observed with elevated algal δ¹⁵N. These results demonstrate the importance of local basin contributions, including those within the lake, to estuarine <em>Microcystis</em> blooms. This suggests that decreasing nutrient loading within the St. Lucie and Caloosahatchee estuaries would help to mitigate these urban blooms. High POM δ¹⁵N values, NO₃^- concentrations, and N:P ratios in the Kissimmee River suggest that expanding urbanization north of the lake represents an increasing human N source contributing to cyanobacterial blooms in Lake Okeechobee.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"139 ","pages":"Article 102710"},"PeriodicalIF":5.5,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142164738","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":"Nitrogen availability controls response of microcystin concentration to phosphorus reduction: Evidence from model application to multiple lakes","authors":"Charlotte Schampera,&nbsp;Ferdi L. Hellweger","doi":"10.1016/j.hal.2024.102711","DOIUrl":"10.1016/j.hal.2024.102711","url":null,"abstract":"<div><p>Microcystis blooms are a global contemporary problem and the mechanisms underlying strain-level ecology (e.g. toxigenic fraction) and toxin (microcystin, MC) production are not sufficiently understood. Recent research suggests that MC synthesis depends on the availability of nitrogen and light, and that they protect toxigenic cells against damage by H₂O₂. The non-toxigenic strains employ the alternative strategy of enzymatic degradation of H₂O₂. Thus, MC-producing cells may have an advantage at high nitrogen and light availability. A model based on this mechanism was able to reproduce the observed patterns of toxigenic fraction and MC concentration in Lake Erie. However, it is unclear if this mechanism also applies to other systems. We investigated this by modeling nine different cases (i.e. lakes, stations, years). The model can reproduce observed patterns (toxigenic fraction, concentration of MC, biomass, nutrients and if available H₂O₂) for all cases, which constitutes support for the proposed mechanism. To explore lake management, we simulated single and dual nutrient (i.e. nitrogen and/or phosphorus) reduction, which predicts two types of outcomes. For lakes with nitrogen limitation at some time during the blooming season (e.g. Lake Erie) a phosphorus only reduction does not reduce MC concentration proportionally and may even increase it. Reducing phosphorus lowers biomass, which increases nitrogen and light availability and raises MC production and toxigenic fraction. For lakes with replete nitrogen (e.g. Lake Taihu) MC concentration is predicted to decrease. Here, further nitrogen availability will not increase MC production. These results advance mechanistic understanding of <em>Microcystis</em> strain ecology and toxin production and provide guidance for management.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"139 ","pages":"Article 102711"},"PeriodicalIF":5.5,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324001446/pdfft?md5=02f09fc27ccfbf35eb3945757c8b3ef9&pid=1-s2.0-S1568988324001446-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142228855","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":"Optimal growth conditions of the haptophyte Chrysochromulina leadbeateri causing massive fish mortality in Northern Norway","authors":"Mathias Fon ,&nbsp;Luka Šupraha ,&nbsp;Tom Andersen ,&nbsp;Silvio Uhlig ,&nbsp;Bente Edvardsen","doi":"10.1016/j.hal.2024.102709","DOIUrl":"10.1016/j.hal.2024.102709","url":null,"abstract":"<div><p>The haptophyte <em>Chrysochromulina leadbeateri</em> formed the most devastating fish-killing algal bloom ever recorded in Norway, in May and June 2019. The bloom resulted in the death of 14,500 tons of farmed salmon in Nordland and Troms Counties and large economic losses to the aquaculture industry in the region. Fish mortalities due to blooms of this species have occurred before in this region in 1991. Environmental conditions promoting bloom formation and growth of <em>C. leadbeateri</em> are, however, still poorly understood. Here we investigated growth as a function of temperature, salinity and irradiance in combinations using a high throughput experimental set-up. Three strains of <em>C. leadbeateri</em> isolated from the 2019 event and an earlier bloom in 1991 were examined. The highest maximal specific growth rate was found at salinities 28–30 and temperatures between 13 and 15 °C, with growth rate generally increasing with irradiance. The upper temperature tolerance for growth for all strains was at 17–19 °C. Further, analyses of the geographical distribution of <em>C. leadbeateri</em> in previous DNA-based studies compiled in the metaPR2 database revealed several ribotypes, and that a cold-water ribotype of <em>C. leadbeateri</em> caused both the 1991 and 2019 blooms.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"139 ","pages":"Article 102709"},"PeriodicalIF":5.5,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324001422/pdfft?md5=8fae5eeaff6d933b38f06aec3e57d5c5&pid=1-s2.0-S1568988324001422-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142058561","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":"Investigating the role of allelochemicals in the interaction between Alexandrium monilatum and other phytoplankton species","authors":"Sylvain Gaillard ,&nbsp;Hamish J. Small ,&nbsp;Nour Ayache ,&nbsp;Simon Tanniou ,&nbsp;Philipp Hess ,&nbsp;Damien Réveillon ,&nbsp;Constance M. Harris ,&nbsp;Thomas M. Harris ,&nbsp;Gail P. Scott ,&nbsp;Alanna MacIntyre ,&nbsp;Kimberly S. Reece","doi":"10.1016/j.hal.2024.102706","DOIUrl":"10.1016/j.hal.2024.102706","url":null,"abstract":"<div><p>Species of the dinoflagellate genus <em>Alexandrium</em> can release bioactive extracellular compounds with allelopathic effects (e.g., immobilization, inhibition of growth, photosynthesis or lysis) towards other phytoplanktonic organisms. In the lower Chesapeake Bay, Virginia, US, succession or co-occurrence of blooms of <em>Akashiwo sanguinea, Margalefidinium polykrikoides</em> and the goniodomin-producing <em>A. monilatum</em> tend to be common during summer months, however the allelopathic potential of <em>A. monilatum</em>, and how it may affect bloom dynamics, has not be studied. We used a rapid fluorescence-based bioassay as well as flow cytometry and an assessment of immobilization to determine the potential effects of <em>A. monilatum</em> culture supernatants on <em>M. polykrikoides, A. sanguinea</em> and the diatom <em>Chaetoceros muelleri</em> (included as a reference strain). In addition, we also investigated the effects of standards of known <em>A. monilatum</em> toxins goniodomin A (GDA) and GDA seco-acid (GDA-sa). Exposure of <em>C. muelleri</em> to culture supernatants from two different strains of <em>A. monilatum</em> resulted in an inhibition of the maximum quantum yield of the photosystem II (F_v/F_m) and cell lysis of the diatom, with strain-specific variation observed, highlighted by a 30-fold difference in the effective concentration resulting in 10 % inhibition (EC₁₀) and 2-fold difference in the lethal concentration resulting in 50 % mortality (LC₅₀) between the two <em>A. monilatum</em> strains tested. Exposure of <em>M. polykrikoides</em> to <em>A. monilatum</em> culture supernatants resulted in a decrease in motility (at ≥ 500 eq. cells mL^-1) along with a decrease in F_v/F_m (at ≥ 1,500 cells mL^-1) and altered cellular morphology (at ≥ 3,500 eq. cells mL^-1). No effect was observed when <em>A. sanguinea</em> was exposed to <em>A. monilatum</em> culture supernatants (at the concentrations tested in these studies). When <em>M. polykrikoides</em> was exposed to the GDA standard, its F_v/F_m (at ≥ 1,951 nM) and motility (at ≥ 390 nM) decreased, and its morphology (at ≥ 975 nM) was modified. The study of supernatant time- and temperature-stability, and the absence of a relationship between observed effects and goniodomin concentrations suggested the presence of additional unknown allelochemicals distinct from goniodomins, as has been observed for other <em>Alexandrium</em> species. Immobilization of <em>M. polykrikoides</em> by <em>A. monilatum</em> culture supernatants and GDA standard in laboratory-based exposure experiments may indicate that <em>A. monilatum</em> has a competitive advantage when both species co-occur in the Chesapeake Bay and this warrants further testing.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"139 ","pages":"Article 102706"},"PeriodicalIF":5.5,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142058560","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}