Harmful Algae最新文献

{"title":"Synchronic distribution of the dinoflagellate Protoceratium reticulatum and yessotoxins in a high stratified fjord system: Tidal or light modulation?","authors":"Patricio A. Díaz ,&nbsp;Gonzalo Álvarez ,&nbsp;Camila Schwerter ,&nbsp;Ángela M. Baldrich ,&nbsp;Iván Pérez-Santos ,&nbsp;Manuel Díaz ,&nbsp;Michael Araya ,&nbsp;María Gabriela Nieves ,&nbsp;Sergio A. Rosales ,&nbsp;Guido Mancilla-Gutiérrez ,&nbsp;Carla Arratia ,&nbsp;Rosa I. Figueroa","doi":"10.1016/j.hal.2024.102649","DOIUrl":"10.1016/j.hal.2024.102649","url":null,"abstract":"<div><p><em>Protoceratium reticulatum</em> is the main yessotoxin-producer along the Chilean coast. Thus far, the yessotoxin levels recorded in this region have not posed a serious threat to human health. However, a bloom of <em>P. reticulatum</em> during the austral summer of 2022 caused the first ban of shellfish collection, due to the high toxin levels. A bloom of <em>P. reticulatum</em> during the austral summer of 2020 allowed an evaluation of the fine-scale distribution of the dinoflagellate during a tidal cycle. High-resolution measurements of biophysical properties were carried out in mid-summer (February 18–19) at a fixed sampling station in Puyuhuapi Fjord, Chilean Patagonia, as part of an intensive 24-h biophysical experiment to monitor the circadian distributions of <em>P. reticulatum</em> vegetative cells and yessotoxins. High <em>P. reticulatum</em> cell densities (&gt;20 × 10³ cells L^–1) were found in association with a warmer (14.5–15 °C) and estuarine (23.5–24.5 g kg^–1) sub-surface water layer (6–8 m). <em>P. reticulatum</em> cell numbers and yessotoxins followed a synchronic distribution pattern consistent with the excursions of the pycnocline. Nevertheless, the surface aggregation of the cells was modulated by the light cycle, suggesting daily vertical migration. The yessotoxin content per <em>P. reticulatum</em> cell ranged from 9.4 to 52.2 pg. This study demonstrates both the value of fine-scale resolution measurements of biophysical properties in a highly stratified system and the potential ecosystem impact of <em>P. reticulatum</em> strains producing high levels of yessotoxins.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"135 ","pages":"Article 102649"},"PeriodicalIF":6.6,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141049850","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":"Ecophysiological responses of Ostreopsis towards temperature: A case study of benthic HAB facing ocean warming","authors":"K. Drouet ,&nbsp;R. Lemée ,&nbsp;E. Guilloud ,&nbsp;S. Schmitt ,&nbsp;A. Laza-Martinez ,&nbsp;S. Seoane ,&nbsp;M. Boutoute ,&nbsp;D. Réveillon ,&nbsp;F. Hervé ,&nbsp;R. Siano ,&nbsp;C. Jauzein","doi":"10.1016/j.hal.2024.102648","DOIUrl":"10.1016/j.hal.2024.102648","url":null,"abstract":"<div><p>Reports of the benthic dinoflagellate <em>Ostreopsis</em> spp. have been increasing in the last decades, especially in temperate areas. In a context of global warming, evidences of the effects of increasing sea temperatures on its physiology and its distribution are still lacking and need to be investigated. In this study, the influence of temperature on growth, ecophysiology and toxicity was assessed for several strains of <em>O.</em> cf. <em>siamensis</em> from the Bay of Biscay (NE Atlantic) and <em>O.</em> cf. <em>ovata</em> from NW Mediterranean Sea. Cultures were acclimated to temperatures ranging from 14.5 °C to 32 °C in order to study the whole range of each strain-specific thermal niche. Acclimation was successful for temperatures ranging from 14.5 °C to 25 °C for <em>O.</em> cf. <em>siamensis</em> and from 19 °C to 32 °C for <em>O.</em> cf. <em>ovata,</em> with the highest growth rates measured at 22 °C (0.54–1.06 d⁻¹) and 28 °C (0.52–0.75 d⁻¹), respectively. The analysis of cellular content of pigments and lipids revealed some aspects of thermal acclimation processes in <em>Ostreopsis</em> cells. Specific capacities of <em>O</em>. cf. <em>siamensis</em> to cope with stress of cold temperatures were linked with the activation of a xanthophyll cycle based on diadinoxanthin. Lipids (neutral reserve lipids and polar ones) also revealed species-specific variations, with increases in cellular content noted under extreme temperature conditions. Variations in toxicity were assessed through the <em>Artemia franciscana</em> bioassay. For both species, a decrease in toxicity was observed when temperature dropped under the optimal temperature for growth. No PLTX-like compounds were detected in <em>O.</em> cf. <em>siamensis</em> strains. Thus, the main part of the lethal effect observed on <em>A. franciscana</em> was dependent on currently unknown compounds. From a multiclonal approach, this work allowed for defining specificities in the thermal niche and acclimation strategies of <em>O</em>. cf. <em>siamensis</em> and <em>O.</em> cf. <em>ovata</em> towards temperature. Potential impacts of climate change on the toxic risk associated with <em>Ostreopsis</em> blooms in both NW Mediterranean Sea and NE Atlantic coast is further discussed, taking into account variations in the geographic distribution, growth abilities and toxicity of each species.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"135 ","pages":"Article 102648"},"PeriodicalIF":6.6,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141055100","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":"First evidence of the induction of domoic acid production in Pseudo-nitzschia australis by the copepod Temora longicornis from the French coast","authors":"Marie Deschler ,&nbsp;Céline Boulangé-Lecomte ,&nbsp;Aurélie Duflot ,&nbsp;Aurore Sauvey ,&nbsp;Caroline Arcanjo ,&nbsp;Romain Coulaud ,&nbsp;Orianne Jolly ,&nbsp;Nathalie Niquil ,&nbsp;Juliette Fauchot","doi":"10.1016/j.hal.2024.102628","DOIUrl":"https://doi.org/10.1016/j.hal.2024.102628","url":null,"abstract":"<div><p>Diatoms of the genus <em>Pseudo-nitzschia</em> are widespread in marine waters. Some of them can produce the toxin domoic acid (DA) which can be responsible for amnesic shellfish poisoning (ASP) when transferred into the food web. These ASP events are of major concern, due to their ecological and socio-economic repercussions, particularly on the shellfish industry. Many studies have focused on the influence of abiotic factors on DA induction, less on the role of biotic interactions. Recently, the presence of predators has been shown to increase DA production in several <em>Pseudo-nitzschia</em> species, in particular in Arctic areas. In order to investigate the relationship between <em>Pseudo-nitzschia</em> species and grazers from the French coast, exposures between one strain of three species <em>(P. australis, P. pungens, P. fraudulenta)</em> and the copepod <em>Temora longicornis</em> were conducted for 5 days. Cellular and dissolved DA content were enhanced by 1,203 % and 1,556 % respectively after the 5-days exposure of <em>P.australis</em> whereas no DA induction was observed in <em>P. pungens</em> and <em>P. fraudulenta. T. longicornis</em> consumed all three <em>Pseudo-nitzschia</em> species. The copepod survival was not related to DA content. This study is an essential first step to better understanding the interactions between planktonic species from the French coast and highlights the potential key role of copepods in the <em>Pseudo</em>-<em>nitzschia</em> bloom events in the temperate ecosystems.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"135 ","pages":"Article 102628"},"PeriodicalIF":6.6,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140844415","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":"Margalefidinium polykrikoides dinoflagellate blooms increase mortality of Acartia tonsa copepods","authors":"Heather K. Corson,&nbsp;Nicole C. Millette","doi":"10.1016/j.hal.2024.102634","DOIUrl":"https://doi.org/10.1016/j.hal.2024.102634","url":null,"abstract":"<div><p>Previous research on phytoplankton blooms has often focused on the initiation of blooms, while studies on the mechanisms underlying bloom decline and termination have been more limited. This study aimed to explore the extent of which <em>Acartia tonsa</em> (copepod) grazing does or does not contribute to <em>Margalefidinium polykrikoides</em> (dinoflagellate) bloom decline. <em>M. polykrikoides</em> is a prominent harmful algal bloom (HAB) species that forms dense blooms in coastal and estuarine systems around the world with known ichthyotoxic effects. Sampling occurred in the lower York River Estuary, Virginia, USA in 2021 and 2022 during two <em>M. polykrikoides</em> blooms. Prey removal experiments were conducted using organisms collected from the field to estimate <em>A. tonsa</em> ingestion rates on <em>M. polykrikoides</em>. While <em>A. tonsa</em> was capable of ingesting <em>M. polykrikoides</em> at low abundance, when <em>M. polykrikoides</em> abundance exceeded 2000 cells mL⁻¹, <em>A. tonsa</em> experienced nearly 100% mortality in the 24-hour prey removal experiments. This suggests that <em>A. tonsa</em> likely cannot exert any top-down control on <em>M. polykrikoides</em> blooms, rather, at high concentrations, <em>M. polykrikoides</em> may act as its own grazing deterrent. Extensive <em>M. polykrikoides</em> blooms could therefore continue to persist due to a reduction in grazing pressure, rather than an increase. This would suggest that the decline of <em>M. polykrikoides</em> blooms is likely caused by another factor. As the frequency, duration, and magnitude of HABs are expected to increase in the future, these findings provide key insights to the trophic interactions that may be influencing the duration of <em>M. polykrikoides</em> blooms.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"135 ","pages":"Article 102634"},"PeriodicalIF":6.6,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324000684/pdfft?md5=59edbc5f092b2be646316a3ffdde1131&pid=1-s2.0-S1568988324000684-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140924505","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":"Okadaic acid as a major problem for the seafood safety (Mytilus galloprovincialis) and the dynamics of toxic phytoplankton in the Slovenian coastal sea (Gulf of Trieste, Adriatic Sea)","authors":"Urška Henigman ,&nbsp;Patricija Mozetič ,&nbsp;Janja Francé ,&nbsp;Tanja Knific ,&nbsp;Stanka Vadnjal ,&nbsp;Jožica Dolenc ,&nbsp;Andrej Kirbiš ,&nbsp;Majda Biasizzo","doi":"10.1016/j.hal.2024.102632","DOIUrl":"https://doi.org/10.1016/j.hal.2024.102632","url":null,"abstract":"<div><p>This article presents the first results on shellfish toxicity in the Slovenian sea (Gulf of Trieste, Adriatic Sea) since the analytical methods for the detection of biotoxins (PSP, ASP, DSP and other lipophilic toxins) in bivalve molluscs were included in the national monitoring program in 2013. In addition to toxins, the composition and abundance of toxic phytoplankton and general environmental characteristics of the seawater (surface temperature and salinity) were also monitored.</p><p>During the 2014–2019 study period, only lipophilic toxins were detected (78 positive tests out of 446 runs), of which okadaic acid (OA) predominated in 97 % of cases, while dinophysistoxin-2 and yessotoxins only gave a positive result in one sampling event each. The number of samples that did not comply with the EC Regulation for the OA group was 17 or 3.8 % of all tests performed, all of which took place from September to November, while a few positive OA tests were also recorded in December, April, and May. This toxicity pattern was consistent with the occurrence pattern of the five most common DSP-producing dinoflagellates, which was supported by the development of warm and thermohaline stratified waters: <em>Dinophysis caudata, D. fortii, D. sacculus, D. tripos</em> and <em>Phalacroma rotundatum</em>. The strong correlation (<em>r</em> = 0.611, <em>p</em> &lt; 0.001) between <em>D. fortii</em>, reaching abundances of up to 950 cells <em>L</em>⁻¹, and OA suggests that <em>D. fortii</em> is the main cause of OA production in Slovenian waters.</p><p>Strong interannual variations in OA and phytoplankton dynamics, exacerbated by the effects of anthropogenic impacts in this coastal ecosystem, reduce the predictability of toxicity events and require continuous and efficient monitoring. Our results also show that the introduction of the LC-MS/MS method for lipophilic toxins has improved the management of aquaculture activities, which was not as accurate based on mouse bioassays.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"135 ","pages":"Article 102632"},"PeriodicalIF":6.6,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324000660/pdfft?md5=71bf147f98fb2f83990ce99ef02cfd92&pid=1-s2.0-S1568988324000660-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140952180","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":"Transoceanic ships as a source of alien dinoflagellate invasions of inland freshwater ecosystems","authors":"Lixia Shang ,&nbsp;Zhangxi Hu ,&nbsp;Yunyan Deng ,&nbsp;Jing Li ,&nbsp;Yuyang Liu ,&nbsp;Xiaoying Song ,&nbsp;Xinyu Zhai ,&nbsp;Zifeng Zhan ,&nbsp;Wen Tian ,&nbsp;Jinxiang Xu ,&nbsp;Yangchun Han ,&nbsp;Hao Shen ,&nbsp;Hua Ding ,&nbsp;Ying Zhong Tang","doi":"10.1016/j.hal.2024.102630","DOIUrl":"10.1016/j.hal.2024.102630","url":null,"abstract":"<div><p>Ships' ballast water and sediments have long been linked to the global transport and expansion of invasive species and thus have become a hot research topic and administrative challenge in the past decades. The relevant concerns, however, have been mainly about the ocean-to-ocean invasion and sampling practices have been almost exclusively conducted onboard. We examined and compared the dinoflagellate cysts assemblages in 49 sediment samples collected from ballast tanks of international and domestic routes ships, washing basins associated with a ship-repair yard, Jiangyin Port (PS), and the nearby area of Yangtze River (YR) during 2017–2018. A total of 43 dinoflagellates were fully identified to species level by metabarcoding, single-cyst PCR-based sequencing, cyst germination and phylogenetic analyses, including 12 species never reported from waters of China, 14 HABs-causing, 9 toxic, and 10 not strictly marine species. Our metabarcoding and single-cyst sequencing also detected many OTUs and cysts of dinoflagellates that could not be fully identified, indicating ballast tank sediments being a risky repository of currently unrecognizable invasive species. Particularly important, 10 brackish and fresh water species of dinoflagellate cysts (such as <em>Tyrannodinium edax</em>) were detected from the transoceanic ships, indicating these species may function as alien species potentially invading the inland rivers and adjacent lakes if these ships conduct deballast and other practices in fresh waterbodies. Significantly higher numbers of reads and OTUs of dinoflagellates in the ballast tanks and washing basins than that in PS and YR indicate a risk of releasing cysts by ships and the associated ship-repair yards to the surrounding waters. Phylogenetic analyses revealed high intra-species genetic diversity for multiple cyst species from different ballast tanks. Our work provides novel insights into the risk of bio-invasion to fresh waters conveyed in ship's ballast tank sediments and washing basins of shipyards.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"135 ","pages":"Article 102630"},"PeriodicalIF":6.6,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140779746","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":"Comparative toxicology of algal cell extracts and pure cyanotoxins: insights into toxic effects and mechanisms of harmful cyanobacteria Raphidiopsis raciborskii","authors":"Zhongshi He ,&nbsp;Youxin Chen ,&nbsp;Jin Gao ,&nbsp;Yewei Xu ,&nbsp;Xinya Zhou ,&nbsp;Rui Yang ,&nbsp;Ruozhen Geng ,&nbsp;Renhui Li ,&nbsp;Gongliang Yu","doi":"10.1016/j.hal.2024.102635","DOIUrl":"10.1016/j.hal.2024.102635","url":null,"abstract":"<div><p>Ongoing research on cyanotoxins, driven by the socioeconomic impact of harmful algal blooms, emphasizes the critical necessity of elucidating the toxicological profiles of algal cell extracts and pure toxins. This study comprehensively compares <em>Raphidiopsis raciborskii</em> dissolved extract (RDE) and cylindrospermopsin (CYN) based on <em>Daphnia magna</em> assays. Both RDE and CYN target vital organs and disrupt reproduction, development, and digestion, thereby causing acute and chronic toxicity. Disturbances in locomotion, reduced behavioral activity, and weakened swimming capability in <em>D. magna</em> have also been reported for both RDE and CYN, indicating the insufficiency of conventional toxicity evaluation parameters for distinguishing between the toxic effects of algal extracts and pure cyanotoxins. Additionally, chemical profiling revealed the presence of highly active tryptophan-, humic acid-, and fulvic acid-like fluorescence compounds in the RDE, along with the active constituents of CYN, within a 15-day period, demonstrating the chemical complexity and dynamics of the RDE. Transcriptomics was used to further elucidate the distinct molecular mechanisms of RDE and CYN. They act diversely in terms of cytotoxicity, involving oxidative stress and response, protein content, and energy metabolism, and demonstrate distinct modes of action in neurofunctions. In essence, this study underscores the distinct toxicity mechanisms of RDE and CYN and emphasizes the necessity for context- and objective-specific toxicity assessments, advocating nuanced approaches to evaluate the ecological and health implications of cyanotoxins, thereby contributing to the precision of environmental risk assessments.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"135 ","pages":"Article 102635"},"PeriodicalIF":6.6,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141056272","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":"Monitoring of toxic cyanobacterial blooms in Lalla Takerkoust reservoir by satellite imagery and microcystin transfer to surrounding farms","authors":"Richard Mugani ,&nbsp;Fatima El Khalloufi ,&nbsp;Minoru Kasada ,&nbsp;El Mahdi Redouane ,&nbsp;Mohammed Haida ,&nbsp;Roseline Prisca Aba ,&nbsp;Yasser Essadki ,&nbsp;Soukaina El Amrani Zerrifi ,&nbsp;Sven-Oliver Herter ,&nbsp;Abdessamad Hejjaj ,&nbsp;Faissal Aziz ,&nbsp;Naaila Ouazzani ,&nbsp;Joana Azevedo ,&nbsp;Alexandre Campos ,&nbsp;Anke Putschew ,&nbsp;Hans-Peter Grossart ,&nbsp;Laila Mandi ,&nbsp;Vitor Vasconcelos ,&nbsp;Brahim Oudra","doi":"10.1016/j.hal.2024.102631","DOIUrl":"https://doi.org/10.1016/j.hal.2024.102631","url":null,"abstract":"<div><p>Cyanobacterial harmful algal blooms (CyanoHABs) threaten public health and freshwater ecosystems worldwide. In this study, our main goal was to explore the dynamics of cyanobacterial blooms and how microcystins (MCs) move from the Lalla Takerkoust reservoir to the nearby farms. We used Landsat imagery, molecular analysis, collecting and analyzing physicochemical data, and assessing toxins using HPLC. Our investigation identified two cyanobacterial species responsible for the blooms: <em>Microcystis</em> sp. and <em>Synechococcus</em> sp. Our <em>Microcystis</em> strain produced three MC variants (MC-RR, MC-YR, and MC-LR), with MC-RR exhibiting the highest concentrations in dissolved and intracellular toxins. In contrast, our <em>Synechococcus</em> strain did not produce any detectable toxins. To validate our Normalized Difference Vegetation Index (NDVI) results, we utilized limnological data, including algal cell counts, and quantified MCs in freeze-dried <em>Microcystis</em> bloom samples collected from the reservoir. Our study revealed patterns and trends in cyanobacterial proliferation in the reservoir over 30 years and presented a historical map of the area of cyanobacterial infestation using the NDVI method. The study found that MC-LR accumulates near the water surface due to the buoyancy of <em>Microcystis</em>. The maximum concentration of MC-LR in the reservoir water was 160 µg L⁻¹. In contrast, 4 km downstream of the reservoir, the concentration decreased by a factor of 5.39 to 29.63 µgL⁻¹, indicating a decrease in MC-LR concentration with increasing distance from the bloom source. Similarly, the MC-YR concentration decreased by a factor of 2.98 for the same distance. Interestingly, the MC distribution varied with depth, with MC-LR dominating at the water surface and MC-YR at the reservoir outlet at a water depth of 10 m. Our findings highlight the impact of nutrient concentrations, environmental factors, and transfer processes on bloom dynamics and MC distribution. We emphasize the need for effective management strategies to minimize toxin transfer and ensure public health and safety.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"135 ","pages":"Article 102631"},"PeriodicalIF":6.6,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324000659/pdfft?md5=759a5964733231c82989ea2cb69c4517&pid=1-s2.0-S1568988324000659-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140823647","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":"A non-microcystin-producing Microcystis wesenbergii strain alters fish food intake by disturbing neuro-endocrine appetite regulation","authors":"Wenyu Long ,&nbsp;Keira Harshaw ,&nbsp;Yunfeng Wang ,&nbsp;Qianqian Xiang ,&nbsp;Yuanyan Zi ,&nbsp;Helene Volkoff ,&nbsp;Hugh J. MacIsaac ,&nbsp;Runbing Xu ,&nbsp;Minmin Niu ,&nbsp;Qiwen Xi ,&nbsp;Xuexiu Chang","doi":"10.1016/j.hal.2024.102647","DOIUrl":"https://doi.org/10.1016/j.hal.2024.102647","url":null,"abstract":"<div><p>Cyanobacterial harmful algal blooms (cHABs) are pervasive sources of stress resulting in neurotoxicity in fish. A member of the widely distributed Microcystis genus of bloom-forming cyanobacteria, <em>Microcystis wesenbergii</em> can be found in many freshwater lakes, including Dianchi Lake (China), where it has become one of the dominant contributors to the lake's recurrent blooms. However, unlike its more well-known counterpart <em>M. aeruginosa</em>, the effects of dense non-microcystin-containing <em>M. wesenbergii</em> blooms are seldom studied. The disturbance of appetite regulation and feeding behaviour can have downstream effects on the growth of teleost fish, posing a significant challenge to aquaculture and conservation efforts. Here we examined the effects of <em>M. wesenbergii</em> blooms on the food intake of <em>Acrossocheilus yunnanensis</em>, a native cyprinid in southern China. This fish species has disappeared in Dianchi Lake, and its reintroduction might be negatively affected by the presence of this newly-dominant <em>Microcystis</em> species. We co-cultured juvenile <em>A. yunnanensis</em> with a non-microcystin-producing strain of <em>M. wesenbergii</em> at initial densities between 5 × 10⁴ and 1 × 10⁶ cells/mL and monitored fish feeding behaviour and changes in neurotransmitter and hormone protein levels. High-density <em>M. wesenbergii</em> cultures increased the feeding rate of co-cultured fish, elevating concentrations of appetite-stimulating signalling molecules (Agouti-related protein and γ-aminobutyric acid), while decreasing inhibitory ones (POMC). These changes coincided with histopathological alterations and reduced somatic indices in brain and intestinal tissues. Given this potential for detrimental effects and dysregulation of food intake, further studies are necessary to determine the impacts of chronic exposure of <em>M. wesenbergii</em> in wild fish.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"135 ","pages":"Article 102647"},"PeriodicalIF":6.6,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1568988324000817/pdfft?md5=11b14e9e76d5182229ac65279b57af08&pid=1-s2.0-S1568988324000817-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141083670","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":"Potential gap in understanding cyanoHABs: Light-dependent morphological variations in colonial cyanobacterium Microcystis","authors":"Ganyu Feng ,&nbsp;Jun Cao ,&nbsp;Huaimin Chen ,&nbsp;Xiang-Zhou Meng ,&nbsp;Zhipeng Duan","doi":"10.1016/j.hal.2024.102622","DOIUrl":"10.1016/j.hal.2024.102622","url":null,"abstract":"<div><p>Colony formation is a crucial characteristic of <em>Microcystis</em>, a cyanobacterium known for causing cyanobacterial harmful algal blooms (cyanoHABs). It has been observed that as <em>Microcystis</em> colonies grow larger, they often become less densely packed, which correlates with a decrease in light penetration. The objective of this study was to investigate the effects of light limitation on the morphological variations in <em>Microcystis</em>, particularly in relation to the crowded cellular environment. The results indicated that when there was sufficient light (transmittance = 100 %) to support a growth rate of 0.11±0.01 day⁻¹, a significant increase in colony size was found, from 466±15 μm to 1030±111 μm. However, under light limitation (transmittance = 50 % – 1 %) where the growth rate was lower than 0, there was no significant improvement in colony size. <em>Microcystis</em> in the light limitation groups exhibited a loose cell arrangement and even the presence of holes or pores within the colony, confirming the negative correlation between colony size and cell arrangement. This pattern is driven by regional differences in growth within the colony, as internal cells have a significantly lower frequency of division compared to peripheral cells, due to intra-colony self-shading (ICSS). The research demonstrates that <em>Microcystis</em> can adjust its cell arrangement to avoid excessive self-shading, which has implications for predicting and controlling cyanoHABs. These findings also contribute to the understanding of cyanobacterial variations and can potentially inform future research on the diverse phycosphere.</p></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"134 ","pages":"Article 102622"},"PeriodicalIF":6.6,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140269613","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}