Harmful Algae最新文献

{"title":"Response of heterocyst differentiation of Dolichospermum to different forms of nitrogen deficiency","authors":"","doi":"10.1016/j.hal.2024.102742","DOIUrl":"10.1016/j.hal.2024.102742","url":null,"abstract":"<div><div>In recent years, initiatives aimed at mitigating eutrophication have successfully reduced nitrogen and phosphorus concentrations in numerous lakes across China. Notably, the management of total nitrogen levels has prompted a shift in the dominant genera responsible for harmful algal blooms. Among these, <em>Dolichospermum</em>, a typical diazotrophic cyanobacterium, exhibits the ability to differentiate heterocysts for atmospheric N₂ fixation under nitrogen-limited conditions. However, the underlying mechanisms driving heterocyst differentiation in response to the absence of specific nitrogen compounds remain poorly understood. This study analyzed the driving factors influencing heterocyst frequency using field data from Lake Chaohu collected between January and June 2022. Furthermore, an experiment was conducted utilizing NH₄Cl, NaNO₃ and urea as nitrogen sources, with specific nitrogen deficiencies created to investigate the response mechanisms of <em>Dolichospermum</em> under these conditions. The results indicated significant monthly variations in heterocyst frequency in Lake Chaohu, which were associated with the interaction of multiple driving factors. Nutrient changes emerged as the most intuitive driving factor, with heterocyst frequency showing a significant negative correlation with total nitrogen and dissolved total nitrogen levels. Experimental results demonstrated that the absence of NO₃<img>N promoted both the biomass and heterocyst frequency of <em>Dolichospermum</em>. When NH_4<img>N was limited, the proliferation of <em>Dolichospermum</em> was inhibited, leading to an extended period of heterocyst development. Although a lack of urea eventually increased heterocyst frequency in <em>Dolichospermum</em>, there was no significant increase in biomass. The concentrations of the three nitrogen sources exhibited a negative correlation with heterocyst differentiation, with the effects of NO₃<img>N and urea deficiency on heterocyst differentiation being significantly stronger than those of NH₄<img>N. Moreover, heterocyst differentiation frequency was positively correlated with photosynthetic efficiency, which indicated that the acquisition and distribution of photosynthetic energy between heterocysts and vegetative cells also influence the differentiation process of heterocysts to some extent. The findings highlight the differing responses of heterocyst differentiation to various forms of nitrogen, emphasizing the importance of prioritizing NH₄<img>N removal in nutrient control. However, further research is needed to determine the key threshold concentrations of different nitrogen sources that trigger heterocyst differentiation.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571861","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":"Identification of novel microcystins in algal extracts by a liquid chromatography–high-resolution mass spectrometry data analysis pipeline","authors":"","doi":"10.1016/j.hal.2024.102739","DOIUrl":"10.1016/j.hal.2024.102739","url":null,"abstract":"<div><h3>Background</h3><div>Microcystins are an emergent public health problem. These toxins are secondary metabolites of harmful cyanobacterial blooms, with blooms becoming more prevalent with eutrophication of water. Exposure to microcystins can result in sickness, liver damage, and even death. Over 300 microcystins have been identified to date, with differences in toxicity based on the specific amino acid composition. Because of this diversity in microcystins, as well as the likelihood of detecting as yet undiscovered microcystins, it is vital to establish a methodological workflow to identify any microcystin in a complex sample, regardless of the availability of a reference standard. Additionally, ascribing varying levels of confidence to these identifications is critical to effectively communicate discoveries.</div></div><div><h3>Methods</h3><div>A liquid-chromatography–high-resolution mass spectrometry method was utilized to identify microcystins present in cyanobacterial extracts from a strain of <em>Microcystis aeruginosa</em> and an <em>Aphanizomenon</em> sp. First, microcystin congeners with available standards were identified in the cyanobacterial extract. These known-unknown microcystins were considered to have the highest confidence identifications due to availability of accurate masses, retention times, and library spectra for comparison. Utilizing the spectra of these microcystins, relatively high-abundance diagnostic product-ions were identified and employed to screen the data for additional candidate microcystins. Microcystins without a standard that had an exact mass matching a microcystin published in CyanoMetDB were considered semi-known-unknown microcystins. The remaining microcystins were considered unknown-unknown microcystins. The identities of the microcystins determined herein were additionally supported by product-ion analysis, thiol reactivity, esterification reactions, neutral loss analysis, and literature contextualization.</div></div><div><h3>Results</h3><div>In total, utilizing the systematic workflow presented herein, 23 microcystins were identified in the <em>M. aeruginosa</em> culture, including two not published previously: [<span>d</span>-Asp³]MC-LCit and the incompletely identified MC-L(C₇H₁₁NO₃).</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586526","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":"Connectivity of toxigenic Pseudo-nitzschia species assemblages between the Northeast U.S. continental shelf and an adjacent estuary","authors":"","doi":"10.1016/j.hal.2024.102738","DOIUrl":"10.1016/j.hal.2024.102738","url":null,"abstract":"<div><div><em>Pseudo-nitzschia</em> harmful algal blooms have recently caused elevated domoic acid in coastal environments of the Northeast United States. In 2017, the toxigenic species <em>P. australis</em> was observed in Narragansett Bay, Rhode Island, a temperate estuarine ecosystem, for the first time since 2009 when DNA monitoring for <em>Pseudo-nitzschia</em> species began. This highly toxic species likely contributed to toxin-related shellfish harvest closures and is hypothesized to have been introduced by an offshore source. Little is known about offshore <em>Pseudo-nitzschia</em> spp. populations in the Northeast Continental Shelf marine ecosystem or how often toxigenic species enter Narragansett Bay through physical processes. Here, we collected filtered biomass samples from multiple time series sites within Narragansett Bay and along the Northeast U.S. Shelf Long-Term Ecological Research transect in winter and summer to investigate the frequency and seasonality of potential <em>Pseudo-nitzschia</em> spp. inflow from the continental shelf to the estuary. Species were taxonomically identified using DNA sequencing of the ITS1 region and domoic acid concentrations were quantified by liquid chromatography with tandem mass spectrometry and multiple reaction monitoring. During six years of sampling, <em>Pseudo-nitzschia</em> species assemblages were more similar between Narragansett Bay and the Northeast shelf in winter than summer, suggesting greater ecosystem connectivity in winter. These winter assemblages were often accompanied by higher domoic acid. Several <em>Pseudo-nitzschia</em> species co-occurred most often with domoic acid and were likely responsible for toxin production in this region, including <em>P. pungens</em> var<em>. pungens, P. multiseries, P. calliantha, P. plurisecta, P. australis</em>, and <em>P. fraudulenta</em>. Domoic acid was detected during periods of relatively low macronutrient concentrations in both seasons, warmer sea surface temperatures in winter, and colder temperatures in summer within this dataset. This study represents some of the first domoic acid measurements on the offshore Northeast U.S. Continental Shelf, a region that supplies water to other coastal environments and could seed future harmful algal blooms. The elevated domoic acid and frequency of hypothesized inflow of toxigenic <em>Pseudo-nitzschia</em> spp. from the Northeast continental shelf to Narragansett Bay in winter indicate the need to monitor coastal and offshore environments for toxins and harmful algal bloom taxa during colder months.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571860","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":"Light-driven differences in bacterial networks and organic matter decomposition: Insights from an analysis of the harmful cyanobacterium Microcystis aeruginosa PCC 7806","authors":"","doi":"10.1016/j.hal.2024.102740","DOIUrl":"10.1016/j.hal.2024.102740","url":null,"abstract":"<div><div>Freshwater systems are critical yet often underestimated components of global carbon cycling, functioning both as carbon sinks and sources. Cyanobacteria play a key role in this cycle by capturing atmospheric carbon dioxide through photosynthesis. The captured carbon is either released back into the atmosphere or sequestered in sediments following organismal decay. This study examines the pivotal role of cyanobacteria, specifically <em>Microcystis aeruginosa</em> PCC 7806, in the biogeochemical cycling of carbon in freshwater ecosystems, with a focus on how light influences the degradation of cyanobacteria-derived organic matter. Using a combination of 16S rDNA sequencing and excitation-emission matrix coupled with parallel factor (EEM-PARAFAC) analysis, we conducted a 50-day experiment to investigate the dynamics of dissolved organic matter (DOM) and lysate organic matter (LOM) derived from <em>M. aeruginosa</em> PCC 7806 under light and dark conditions. Our results demonstrate that light significantly impacts bacterial community composition, gene functionality, and the decomposition of organic matter. The findings emphasize the crucial role of light in facilitating microbial adaptation, stabilizing microbial networks and driving organic substrate transformation. These insights underscore the influence of light on microbial community dynamics and organic matter degradation, revealing shifts in microbial populations under varying light conditions. This suggests a strong link between photochemical processes and microbial activity, with significant ecological implications.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561082","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":"Discovery of novel and known viruses associated with toxigenic and non-toxigenic bloom forming diatoms from the Northern Adriatic Sea","authors":"","doi":"10.1016/j.hal.2024.102737","DOIUrl":"10.1016/j.hal.2024.102737","url":null,"abstract":"<div><div>Algal blooms impact trophic interactions, community structure and element fluxes. Despite playing an important role in the demise of phytoplankton blooms, only few viruses infecting diatoms have been cultured. <em>Pseudo-nitzschia</em> is a widespread diatom genus that commonly blooms in coastal waters and contains toxin-producing species. This study describes the characterization of a novel virus infecting the toxigenic species <em>Pseudo-nitzschia galaxiae</em> isolated from the northern Adriatic Sea. The ssRNA virus PnGalRNAV has 29.5 nm ± 1.2 nm icosahedral virions and a genome size of 8.8 kb. It belongs to the picorna-like <em>Marnaviridae</em> family and shows high specificity for <em>P. galaxiae</em> infecting two genetically and morphologically distinct strains. We found two genetically distinct types of this virus and screening of the global virome database revealed matching sequences from the Mediterranean region and China, suggesting its global distribution. Another virus of similar shape and size infecting <em>Pseudo-nitzschia calliantha</em> was found, but its genome could not be determined. In addition, we have obtained and characterized a new virus that infects <em>Chaetoceros tenuissimus</em>. The replicase protein of this virus is very similar to the previously described ChTenDNAV type-II virus, but it has a unique genome and infection pattern. Our study is an important contribution to the collective diatom virus culture collection and will allow further investigation into how these viruses control diatom bloom termination, carbon export and toxin release in the case of <em>Pseudo-nitzschia</em>.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533604","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":"Accumulation and depuration of 4,5-dihydro-KmTx2 from Karlodinium veneficum in the bivalves, Mercenaria mercenaria and Sinonovacula constricta","authors":"","doi":"10.1016/j.hal.2024.102736","DOIUrl":"10.1016/j.hal.2024.102736","url":null,"abstract":"<div><div>Bivalves (e.g., clams, oysters, mussels, scallops) are a significant part of the global diet and are harvested for their nutritional value, but as filter feeders they are susceptible to the accumulation of toxins produced by certain species of phytoplankton. Karlotoxins (KmTxs) are a class of amphidinol-like compounds with hemolytic, ichthyotoxic, and cytotoxic properties that have been associated with harmful algal blooms, and the dinoflagellate <em>Karlodinium veneficum</em> uses KmTxs to facilitate prey capture and deter grazing by other organisms. In this work, we examined the accumulation and depuration of 4,5-dihydro-KmTx2, a karlotoxin previously isolated from <em>K. veneficum</em>, in two bivalves with different life habits, i.e., <em>Sinonovacula constricta</em> Lamarck and <em>Mercenaria mercenaria</em> Linnaeus. After both bivalves received <em>K. veneficum</em> GM5 in their feed for a long period of 10 days, 4,5-dihydro-KmTx2 was accumulated considerably in the visceral mass, but there was almost no toxin accumulation in the muscle. The accumulation was more severe for <em>M. mercenaria</em> than <em>S. constricta</em>. The toxin was cleared almost completely from the bivalves 5 days after <em>K. veneficum</em> GM5 was removed from the feed. For both bivalves, the bait microalgae <em>I. galbana</em> slowed both the accumulation and the depuration of the toxin.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533010","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":"Ciguatera poisoning: A review of the ecology and detection methods for Gambierdiscus and Fukuyoa species","authors":"","doi":"10.1016/j.hal.2024.102735","DOIUrl":"10.1016/j.hal.2024.102735","url":null,"abstract":"<div><div>Ciguatera poisoning is the most prevalent non-bacterial seafood illness globally, with an estimated 10,000 to 50,000 human cases reported annually. While most symptoms are generally mild, some cases can result in severe and long-lasting neurological and psychological damage, and in some instances, even death. The known causative agents of ciguatera poisoning are benthic toxic dinoflagellate species belonging to the genera <em>Gambierdiscus</em> and <em>Fukuyoa</em>. These species produce highly potent ciguatoxins that bioaccumulate through the marine food chain, eventually reaching humans through seafood consumption. Although <em>Gambierdiscus</em> and <em>Fukuyoa</em> species are widespread in tropical waters worldwide, the full extent of their distribution remains uncertain. This review provides a detailed examination of the ecological dynamics of these dinoflagellates and explores the diverse range of detection methods used to monitor them. These include a focus on molecular techniques for detection, alongside morphological methods, emerging technologies, and a toxin detection overview. Additionally, we offer recommendations on how the field can advance, highlighting novel solutions and next steps for improving detection and monitoring practices. By assessing the strengths and limitations of current approaches and proposing directions for future research, this review aims to support efforts in better understanding and mitigating the risk of ciguatera poisoning.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446134","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":"Defining algal bloom phenology in Lake Erie","authors":"","doi":"10.1016/j.hal.2024.102731","DOIUrl":"10.1016/j.hal.2024.102731","url":null,"abstract":"<div><div>Elucidating the impact of global climate change on aquatic ecosystems, particularly through phenological shifts in primary producers, is critical for understanding ecological resilience. Here, we focus on the phenological shifts in chlorophyll as a proxy for algae biomass and primary production in aquatic ecosystems, specifically in Lake Erie as well as concentrations of the toxin microcystin. By tracking temporal changes in each, we identified key phenological phases important to estimate duration, magnitude, and intensity of harmful algal blooms (HABs). Determining which influential biotic and abiotic factors such as temperature, wind speed, nutrient availability, and climate change is most important, is a long-term management need for Lake Erie, which can be explored using our methodology. Our novel statistical framework employing Bayesian generalized additive mixed models described seasonal chlorophyll and particulate microcystin concentration from Lake Erie and our simple geometric method identified the start, peak, and end of algal blooms. This research enhances our understanding of the ecological effects of nutrient pollution on aquatic ecosystems and provides a repeatable method for determining phenological events without the need for user defined cutoffs which aids in the management and mitigation of HABs, safeguarding water quality in regions dependent on lakes for drinking water.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533605","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":"Predator-induced defense decreases growth rate and photoprotective capacity in a nitrogen-limited dinoflagellate, Alexandrium minutum","authors":"","doi":"10.1016/j.hal.2024.102734","DOIUrl":"10.1016/j.hal.2024.102734","url":null,"abstract":"<div><div>Some dinoflagellates produce toxic secondary metabolites that correlate with increased resistance to grazers. The allocation costs of toxin production have been repeatedly addressed, but with conflicting results. Few studies have considered the potential costs of this defense to the photosystem, even though defense toxins (e.g., karlotoxins and brevetoxins) are closely linked to the photoprotective process. Here, we used chemical cues from copepods to induce paralytic shellfish toxin (PST) production in resource-limited <em>Alexandrium minutum</em> and quantitatively determined the growth rate and potential trade-offs with the photosystem process. The results show that grazer-induced, more toxic <em>A. minutum</em> had larger cell volume, lower cell division rate, and lower pigment content under nitrogen-limited conditions than control cells. In addition, predator cues led to a lower relative abundance of photoprotective xanthophylls and a reduced de-epoxidation efficiency of the xanthophyll cycle under high light conditions, reducing the ability of the cells to resist photodamage. Decreased photoprotective capacity may reflect an overlooked defense cost of toxin production.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142417518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The occurrence patterns and alternative host use of the generalist parasitoid Parvilucifera infectans (Alveolata, Perkinsozoa) of marine dinoflagellates revealed by a high-frequency time series microscopic data at a temperate coastal site","authors":"","doi":"10.1016/j.hal.2024.102732","DOIUrl":"10.1016/j.hal.2024.102732","url":null,"abstract":"<div><div>Species belonging to the genus <em>Parvilucifera</em> (Alveolata, Perkinsozoa) are known as generalist parasitoids that can infect a variety of marine dinoflagellates and ultimately kill the host cell. Despite the accumulation of knowledge on <em>Parvilucifera</em> parasitoids over the last twenty years, the occurrence pattern and use of alternative hosts for persistent transmission within fluctuating natural dinoflagellate host communities have received relatively little attention. To address this, high-frequency (i.e., daily) time series protist monitoring was conducted for 411 days, from April 2020 to May 2021, at a temperate coastal site in Jinhae Bay, Republic of Korea. This site was characterized by frequent blooms of mixed dinoflagellates throughout most of the year. Nonetheless, <em>Parvilucifera</em> infections were detected only in the spring seasons, and its occurrence pattern was primarily governed by the presence and cell density of its primary dinoflagellate host, <em>Akashiwo sanguinea</em>. As long as the primary host was present at high densities (greater than 10⁴ cells L^-1), this primary host alone could support the transmission and persistence of the parasitoid. However, if the cell density of the primary host started to decline, then <em>Parvilucifera</em> searched for and exploited alternative hosts for its continued survival. Taken together, this study suggests that the presence and cell density of its preferred primary host species and the duration for which the density remains above the threshold level are key factors that regulate the timing of <em>Parvilucifera</em> occurrence and alternative host use.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142417519","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}