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The Arctic Ocean is currently undergoing significant transformations due to climate change, leading to profound changes in its microbial planktonic communities. These communities consist of a wide range of organisms, including photoautotrophic prokaryotes and eukaryotes, as well as heterotrophic, phagotrophic, and mixotrophic protistan species. Here, for simplicity, we refer to these single-celled species as phytoplankton. Within this diversity, potentially toxic and/or harmful algal species (hereafter abbreviated as "HA") are of particular concern. These organisms have the potential to spread into Arctic waters, posing threats to both human and ecosystem health. Despite their importance, the spatial and temporal distribution of phytoplankton communities, including HA species, in the North American Arctic, remains poorly understood. To address this gap, we compiled and synthesized the largest possible body of data from different databases, individual published and unpublished datasets, and partitioned it into nine regions based on the Large Marine Ecosystem classification. Our dataset contains 385 800 individual georeferenced data points and 18 268 unique sampling events, revealing greater diversity than previously thought, with 1445 unique taxa. Heterokontophyta (which notably included diatoms) and Dinoflagellata were the most dominant phyla. Our results indicate distinct spatial patterns of diversity, with the highest diversity observed in Atlantic-influenced regions of the North American Arctic. For most of the HA species recorded in our database, no evidence was found for an increase in the northernmost latitude where HA species are observed over the years, meaning that there is no substantial spread of HA species into the North American part of the Arctic. Our study challenges the traditional view of the Arctic as being unsuitable for toxin-producing and harmful algae and highlights the importance of extensive and long-term sampling efforts to understand the region's biodiversity. Overall, our findings provide new insights into the spatial patterns and biodiversity of phytoplankton and other protists in the North American Arctic and have implications for understanding the ecological functioning and response of this region to ongoing climate change. [ABSTRACT FROM AUTHOR]

As the eutrophication of natural water bodies becomes more and more serious, the frequency of outbreaks of harmful algal blooms (HABs) mainly formed by harmful algae also increases. HABs have become a global ecological problem that poses a serious threat to human health and food safety. Therefore, it is extremely important to establish methods that can rapidly detect harmful algal species for early warning of HABs. The traditional morphology-based identification method is inefficient and inaccurate. In recent years, the rapid development of molecular biology techniques has provided new ideas for the detection of harmful algae and has become a research hotspot. The current molecular detection methods for harmful algal species mainly include fluorescence in situ hybridization, sandwich hybridization, and quantitative PCR (qPCR), but all of these methods can only detect single harmful algal species at a time. The establishment of methods for the simultaneous detection of multiple harmful algal species has become a new trend in the development of molecular detection technology because various harmful algal species may coexist in the natural water environment. The established molecular techniques for multiple detections of harmful algae mainly include gene chip, multiplex PCR, multiplex qPCR, massively parallel sequencing, antibody chip, and multiple isothermal amplification. This review mainly focuses on the principles, advantages and disadvantages, application progress, and application prospects of these multiple detection technologies, aiming at providing effective references not only for the fisheries but also for economic activities, environment, and human health. [ABSTRACT FROM AUTHOR]

The toxin‐producing dinoflagellate Alexandrium pseudogonyaulax has become increasingly abundant in northern European waters, replacing other Alexandrium species. A. pseudogonyaulax produces goniodomins and lytic substances, which can be cytotoxic toward other organisms, including fish, but we still know little about the environmental conditions influencing its growth and toxicity. Here, we investigated the impacts of different nitrogen sources and light intensities, common bottom‐up drivers of bloom formation, on the growth and toxin content of three A. pseudogonyaulax strains isolated from the Danish Limfjord. While the growth rates were significantly influenced by nitrogen source and light intensity, the intracellular toxin contents only showed strong differences between the exponential and stationary growth phases. Moreover, the photophysiological response of A. pseudogonyaulax showed little variation across varying light intensities, while light‐harvesting pigments were significantly more abundant under low light conditions. This study additionally highlights considerable physiological variability between strains, emphasizing the importance of conducting laboratory experiments with several algal strains. A high physiological plasticity toward changing abiotic parameters points to a long‐term establishment of A. pseudogonyaulax in northern European waters. [ABSTRACT FROM AUTHOR]

DINOPHYSIS NUTRITIONAL SOURCES I Dinophysis i species are obligate mixotrophs that require ciliate prey (e.g., I Mesodinium i species), light, and nutrients for sustained growth (Hansen et al., [16]; Kim, Kim, et al., [22]). These two issues are dealt with and all available results related to I Dinophysis i and their toxins in the United States are reviewed in: "A survey of I Dinophysis i spp. and their potential to cause diarrhetic shellfish poisoning in coastal waters of the United States" (Ayache et al., [3]). A synoptic view of the current distribution of I Dinophysis i species and reported DSP events (Figure 1) confirms that occurrence of toxic outbreaks is determined by the composition (profile and content) of local strains and the shellfish species affected (Blanco, [4]). Species of I Dinophysis i produce diarrhetic toxins and pectenotoxins and frequently cause harvesting bans in intensive shellfish cultivation sites in Western Europe, Chile, Perú, and Japan (Reguera et al., [29]). [Extracted from the article]

The evaluation of water quality is commonly conducted by measuring physicochemical parameters. However, to enable identification of water quality changes of aquatic ecosystems, such as lakes, requires long time series data sampling. In this study, we performed water quality assessments by utilising the presence of potential harmful algae presence in Lake Ranu Grati, Indonesia. We conducted water sampling to evaluate 13 water quality parameters (in-situ and ex-situ) and identified the phytoplankton community structure of the lake at seven sampling sites from December 2018 to February 2019. To assess the water quality of the lake, we used two approaches. First, calculated the classical water quality index using the STORET method. Second, identified the potential harmful algae from the phytoplankton community structure of Lake Ranu Grati, and then determined the water quality factors related to its occurrence using canonical correspondence analysis. The results showed that water quality condition of Lake Ranu Grati was optimum except for COD, BOD and ammonia. The STORET index also classified the seven sites in Lake Ranu Grati as lightly polluted and moderately polluted. Considering the presence of potentially harmful algae from the Cyanophyta and Euglenophyta divisions, it was suggested that Sites 6 and 7 were the most polluted areas of Lake Ranu Grati, which corresponded to the high concentration of COD and BOD. This finding indicates that agricultural and aquaculture activities around the lake need to be controlled to maintain the sustainability of the water quality condition of Lake Ranu Grati. [ABSTRACT FROM AUTHOR]

Various harmful microalgae coexist in the marine environment, seriously affecting the survival of aquatic animals, the sustainable development of fisheries, and pose a great threat to the safety of aquatic food. Consequently, monitoring these harmful microalgae in the marine aquaculture environment is an urgent issue that needs to be addressed. This paper focused on developing a multiplex polymerase chain reaction (MPCR) assay for the simultaneous detection of representative harmful microalgae commonly distributed in the aquaculture environment along the Chinese coast, including Karenia mikimotoi, Alexandrium tamarense, Chattonella marina, Prorocentrum minimum and Heterosigma akashiwo. First, the internal transcribed spacer and large subunit rDNA of target algal species were selected as target for the design of MPCR primers, the specificity of which was subsequently verified. Next, the MPCR system was established and the reaction conditions were optimized, including primer concentration, dNTP concentration, Mg2+ concentration, the concentration of Taq DNA polymerase, and annealing temperature. Specificity test showed that the established MPCR did not cross-react with all of the control algal species and thus can be used for specific detection of target algal species. The sensitivity test showed that the established MPCR could still detect all of the target algae when the concentration of genomic DNA was as low as 1 ng µL–1. Moreover, the MPCR could still detect K. mikimotoi when the concentration of genomic DNA was as low as 1 pg µL–1. The stability test indicated that the performance of the developed MPCR was not affected by the interfering algal species. In addition, the practicality of the established MPCR assay was evaluated using spiked water samples. The tests with the spiked samples indicated that the detection limit of MPCR for the all of the target algal species was approximately 4 cells mL−1, which can meet the requirement for the warning of HABs caused by them. In conclusion, the MPCR assay established here is characterized with strong specificity and good stability and is expected to be promising for daily monitoring of harmful microalgae in the aquaculture environment as an important alternative to traditional morphology-based methods. [ABSTRACT FROM AUTHOR]

Cyanobacteria harmful algal blooms (cHABs) are increasingly becoming an emerging threat to aquatic life, ecotourism, and certain real estate investments. Their spontaneous yet sporadic occurrence has made mitigation measures a cumbersome task; moreover, current trends regarding anthropogenic activities, especially in agriculture and industry portend further undesirable events. Apart from the aesthetic degeneration they create in their respective habitats, they are equally capable of secreting toxins, which altogether present grave environmental and medical consequences. In this paper, we gave an update on factors that influence cHABs, cyanotoxin exposure routes, and environmental public health implications, especially impacts on fish, pets, and livestock. We discussed social economic impacts, risk assessment, and management problems for cHABs and, thereafter, assessed the extant management approaches including prevention, control, and mitigation of the proliferation of cyanobacterial blooms. In light of this, we suggest that more intensified research should be directed to the standardization of procedures for cyanotoxin analysis. Also, the provision of standardized reference material for the quantification of cyanotoxins is vital for routine monitoring as well as the development of strong in situ sensors capable of quantifying and detecting HABs cells and toxins in waterbodies to prevent the adverse impacts of cHABs. Also, more investigations into the natural and environmentally friendly approach to cyanobacteria management and the necessary and appropriate deployment of artificial intelligence are required. Finally, we wish to redirect the focus of public health authorities to protecting drinking water supply sources, agriculture products, and food sources from cyanotoxins contamination as well as to implement proper monitoring and treatment procedures to protect citizens from this potential health threat. [ABSTRACT FROM AUTHOR]

To develop a variety of algaecides for harmful algae control that cause water pollution, we synthesized a series of 79 derivatives based on the structure of N1-benzyl-N3, N3-diethylpropane-1,3-diamine and analyzed their structure-activity relationships toward a harmful and a harmless algal species. Among the derivatives, the best algicidal activities with LC50 values of 0.49 (compound 24) and 0.42 µM (compound 34) in Cyanobacteria, respectively were achieved when CH3 and F groups were substituted at the R2 position, with CH3CH3 group at the R3 position, and amine chain length 3 at the R4 position after fixing Cl substituent group at the R1 position of the benzaldehyde group. The compounds 24 and 34 decreased the chlorophyll content of treated groups by approximately 75–80% as compared to the control. Algicidal activities for harmful algal species were as follows, in the order of greatest to the least: Microcystis sp. > Microcystis aeruginosa > Hererocapsa circularisquama > Chattonella marina > Heterosigma akashiwo. The acute toxicities of compounds 24 and 34 against Daphnia magna showed EC50 values of 20.18 and 22.32 µM, respectively, which were approximately 46.4 and 44.69 times higher than the LC50 value against Microcystis sp., showing low ecotoxicity. In the case of Danio rerio, they showed very low ecotoxicity with EC50 values of 94.97 and 45.97 µM, respectively. These results indicate that compounds 24 and 34 could be potential agents for selectively controlling harmful algal blooms. [ABSTRACT FROM AUTHOR]

Freshwater cyanobacterial harmful algae blooms (cHABs) are a major threat to human and environmental health and are increasing globally in frequency and severity. To manage this threat in a timely manner, science must focus on increasing our ability to predict the growth and toxigenicity of specific taxa of cyanobacteria.Recent molecular research has revealed striking genomic and metabolic diversity among the many morphologically indistinguishable sub‐species and strains of cyanobacteria. Assemblage‐level molecular metabolic capability surveys promise to improve our ability to predict cyanobacterial responses to environmental forcing, but many of these cutting‐edge techniques are not widely available or cost‐effective enough to be employed in routine monitoring programmes to support management decisions. Taxonomic ambiguity, cryptic functional specialisation, incongruence between genomic capability and phylogeny, and genomic flexibility impose severe challenges to our ability to ascribe autecological attributes at a level of taxonomic resolution that is attainable under current management strategies (i.e. Linnaean species). This lack of knowledge prohibits reliable predictions of species' responses to environmental stressors.Cyanobacterial species comprise consortia of metabolically diverse, morphologically indistinct strains that span a range of ecological specialisation. Under current, broadly applied taxonomic concepts, these species functionally embody a generalist ecological strategy—persisting and/or proliferating where other specialised competitors are negatively impacted.We postulate that within current management frameworks, characterising of cyanobacterial species as competing generalists, as well as considering abundance trajectories of well‐characterised, non‐cyanobacterial specialist phytoplankton will generate more scalable, mechanistic, and management‐relevant insight into increasing cHAB frequency and severity in suitable time frames.Here we recommend that cHAB management considers the competitive framework of phytoplankton communities, including cyanobacteria, wherein diverse environmental changes lead to deterministic responses by readily identifiable, documented specialist taxa. Characterising these changes in community structure will quantify the relative importance of altered stressors and resource availability that can be exploited by metabolically flexible cyanobacteria. [ABSTRACT FROM AUTHOR]

Harmful algae blooms (HABs) are unwelcome annual events on waterbodies in California (USA). The unseemly sights of lifeless fish drifting ashore and the mammalian illnesses resulting from close contacts with HABs once in ahile are telltale signs of their presence. California as such tracks HABs closely for immediate public warnings. That said, a lack of statewide monitoring standards for producing comparable and high-quality data, however, hinders a deeper insight into HABs on California's inland waterbodies. In their absence, the current study demonstrates the utility of empirical dataset in advancing an understanding of spatiotemporal distribution of HABs on inland waterbodies. With a 2016–2021 mostly observational data, the questions asked are whether HABs incidences are expanding in California with time, whether there are localities more prone to HABs than others, and whether bivariate relationships exist between HABs reports and population density, or waterbody size, land area and geographical location. Overall, the frequency with which HABs are observed is found to increase statewide, an increase not correlated with population density, but with land area and inland waterbody size. Results also show that North Coast, Central Valley, and San Diego are the most affected regions of California. Also revealed by this mostly observational data were recent HABs spikes in the January months (California winter) which, if proven, may be signaling an emerging year-round problem that California will have to contend with. [ABSTRACT FROM AUTHOR]

Simple Summary: Harmful algae are those which release toxins to the aquatic ecosystems. Excessive growth of these algae can kill fish, create anoxia, impede aquaculture activities and contaminate aquatic food. Therefore, it is important to investigate their occurrence, diversity and abundance in pond aquaculture systems. In this study, we have identified 81 genera of harmful algae from 30 coastal homestead ponds mainly consisting of Microcystis spp. (30.14%) and Actinoptycus spp. (18.32%). Based on taxonomic classes, the community assemblage was dominated by Cyanophyceae, Chlorophyceae and Bacillariophyceae. Statistical analyses demonstrated that that dissolved oxygen, nitrates, phosphates, sulphates, salinity and transparency influence the abundance of identified algal genera. Algae are the naturally produced food for fish in any aquatic ecosystem and an indicator of a productive pond. However, excess abundance of harmful algae can have detrimental effects on fish health. In this study, the algal communities of 30 coastal homestead fish ponds were investigated to identify the diversity, assemblage and controlling environmental variables of harmful algae from a tropical coastal area. The findings showed that 81 of the 89 genera of identified algae were harmful, with the majority of them being in the classes of Cyanophyceae (50.81%), Chlorophyceae (23.75%), Bacillariophyceae (9.5%), and Euglenophyceae (8.47%). Microcystis spp. alone contributed 28.24% to the total abundance of harmful algae. Significant differences (p < 0.05) in algal abundance were found among the ponds with the highest abundance (470 ± 141.74 × 103 cells L−1) at pond (S25) near agricultural fields and the lowest abundance (109.33 ± 46.91 × 103 cells L−1) at pond (S14) which was lacking sufficient sunlight and nutrients. Diversity indices, e.g., dominance (D), evenness (J′), richness (d) and Shannon diversity index (H′) ranged from 0.17 to 0.44, 0.23 to 0.6, 0.35 to 2.23 and 0.7 to 1.79, respectively, indicating a moderate range of diversity and community stability. Community composition analysis showed the assemblage was dominated by Cyanophyceae, Chlorophyceae and Bacillariophyceae, whereas, multivariate cluster analyses (CA) identified 11 major clusters. To identify the factors controlling their distribution or community assemblages, eight environmental variables (temperature, pH, dissolved oxygen (DO), salinity, transparency, nitrates, phosphates and sulphate) were measured. ANOVA analysis showed that the variables significantly differed (p < 0.05) among the ponds, and canonical correspondence analysis (CCA) demonstrated that DO, nitrates, phosphates, sulphates, salinity and transparency have the most impact on the abundance of algal genera. In addition, analyses with Pearson's correlation coefficient showed that the abundance of total algae, diversity and community were mainly governed by phosphates and sulphates. These results can be used to identify and control these toxic algal groups in the local aquaculture sector. [ABSTRACT FROM AUTHOR]

Phytoplankton plays an essential role in the biogeochemical cycle because it is at the top of the food chain and is a source of oxygen. Eutrophication causes coastal areas to deteriorate as industrialization accelerates, leading to harmful algal blooms (HABs), severely affecting human and ecological health. The frequency and extent of HAB events potentially may increase due to climate change. HAB outbreaks have led to substantial losses for major coastal economies globally, and therefore have emerged as a critical research focus in environmental sciences. However, the lack of an overview of diverse factors influencing HABs complicates the cause identification and the effective countermeasure development for HAB occurrence, thereby impeding the formulation of targeted strategies for prediction and mitigation. Therefore, this review summarizes the influential factors affecting HABs in coastal areas, including water quality factors (nutrients, salinity, stratification, and biological factors) and climatological factors (temperature, pH and pCO2 , and irradiance and light). Recent work with several harmful algae species suggested that warmer temperatures combined with nutrient variation, stronger stratification, and ocean acidification may increase the growth of some toxic dinoflagellate species. Although the effects of factors vary for different species and locations, the intensification of anthropogenic activities and climate change likely will increase the frequency, outbreak scale, and severity of most coastal HABs. Because predicting HABs is crucial for understanding the factors and synergy affecting their growth and minimizing losses for decision makers and stakeholders, we reviewed models for predicting HABs, including process-based models, traditional statistical-empirical models, and data-driven machine learning models. Predicting HABs becomes more challenging as the spatial distribution of harmful algae is influenced by future climate patterns. This review paper presents a comprehensive overview of the various factors impacting HABs in coastal areas, serving as a valuable resource for decision makers and researchers to design targeted research and mitigation strategies. [ABSTRACT FROM AUTHOR]

Algal blooms formed by some phytoplankton species can produce toxins or alter environmental conditions that can affect aquatic organisms and water quality, with impacts on the aquaculture and fisheries industries that can pose a risk to public health. The ABSa15 cell line and fish erythrocytes were the most sensitive to these extracts (up to 74.5% loss of viability and 100% haemolysis, respectively), confirming the haemolytic and cytotoxic effects of this dinoflagellate [[19]]. A previous study confirmed the sensitivity of the RTgill-W1 cells towards the two brevetoxins PbTx-2 and PbTx-3 purified from I K. brevis i , the karlotoxin KmTx-2 from the dinoflagellate I Karlodinium veneficum i , and paralytic shellfish toxins from I Alexandrium i spp. [[28], [31]], confirming the suitability of this assay for I in vitro i - I in vivo i correlations. 34564605 36 Industry - Aquaculture New ZealandAvailable online: https://www.aquaculture.org.nz/resources/general(accessed on 7 May 2023) 37 Rolton A., Rhodes L., Hutson K.S., Biessy L., Bui T., Mackenzie L., Symonds J.E., Smith K.F. Effects of Harmful Algal Blooms on Fish and Shellfish Species: A Case Study of New Zealand in a Changing Environment. [Extracted from the article]

Myriophyllum aquaticum has shown potential allelopathic effects for the biocontrol of cyanobacteria and cyanotoxins. However, the composition of allelochemicals and their biological effects may be influenced by seasonal changes. In this study, we investigated the impact of aqueous extracts of M. aquaticum collected in different seasons on the growth of Microcystis aeruginosa and the concentration of microcystin-LR. Plant samples were extracted using ultrasound cycles in aqueous solutions, and extracts at varying concentrations (0.1, 10, and 100 mg/L) and a control treatment were inoculated with M. aeruginosa, and cell growth was analyzed using a Neubauer chamber. Photosynthetic pigment quantification was used to measure physiological effects and liquid chromatography was used to evaluate the microcystin-LR concentrations. The extracts of plants collected during autumn and winter exhibited higher inhibition of M. aeruginosa growth and a reduction in photosynthetic pigments compared to those collected during spring and summer. These results can be explained by the higher presence of phenolic compounds in the composition of extracts from autumn and winter. Microcystin-LR concentrations were decreased at 10 and 100 mg/L, with the highest efficiency observed in autumn, while spring showed lower efficiency. Our findings suggest that M. aquaticum extracts have inhibitory potential on M. aeruginosa, particularly during the autumn season, making them a promising nature-based solution for the biocontrol of harmful algal blooms. [ABSTRACT FROM AUTHOR]

To assist the researches of toxic and harmful algae and provide government workers with judgment basis for decision-making related events, we established a biological information management system for toxic and harmful algae in China's offshore to assist relevant research. In this study, Karenia mikimotoi was studied as a typical toxic and harmful algae species, and the basic biological information and biogeographic distribution information of K. mikimotoi were systematically studied and collected. In the part of basic biological information, the name, toxin, and molecular characteristic sequence of K. mikimotoi were sorted out by literature searching and website browsing. Through experimental means, the relevant information of morphological identification, pigment composition, and lipid composition were obtained. In the part of biogeographic distribution information, this study sorted out the information of K. mikimotoi, analyzed the characteristics of its occurrence, and completed the standardized construction of biogeographic distribution information. Through the collation of basic biological information and biogeographic distribution information of K. mikimotoi, the standardization of related information was completed, which provided template and method reference for information collection of other toxic and harmful algae species, which was beneficial to the database analysis and design. [ABSTRACT FROM AUTHOR]

The "harmful algae and algal toxins in coastal waters of China: investigation and database" project (HAATC) is funded (US$2.3 million) by the Ministry of Science and Technology of China for 60 months starting on the 1st Jan 2019. Since the 1990s, national projects and other related work have greatly improved harmful algal bloom (HAB) research in China. However, the existing research on HABs is often limited to specific sea areas or specific algal bloom disasters, which is insufficient for understanding the long-term evolution of HAB occurrence under the influence of intensified human activity and global change. The HAATC project intends to determine the overall distribution of marine harmful microalgae and macroalgae, and marine algal toxins (in phytoplankton and shellfish) through a large-scale investigation in the coastal waters of China and continuous investigation in key sea areas. It also aims to observe biotic and abiotic processes during harmful red tides and green tides, and establish an open database and query platform of HABs in China. The research consortium, led by chief scientist Prof. Tian YAN, includes approximately 100 scientists and students. More than 2 years of work have shown the increased distribution of HAB species (including cysts) and algal toxins in China's coastal waters, the increased occurrence of macroalgae blooms (mainly by Ulva prolifera and Sargassum horneri) in the Southern Yellow Sea, increased amount of causative species being identified due to the use of molecular technologies in taxonomy, and new records of algal toxins such as azaspiracid, cycloimines and neurotoxins β-N-methylamino-l-alanine have been detected, which complicates the research in algal toxins and toxicology. Eventually, the project will provide systematic basic data and techniques for the rapid and accurate identification of harmful algae species to support the research, monitoring, and control of harmful algal blooms, as well as seafood safety management in China. [ABSTRACT FROM AUTHOR]

Climate change is leading to an increase in severity, frequency, and distribution of harmful algal blooms across the globe. For many harmful algae species in eutrophic lakes, the formation of such blooms is controlled by three factors: the lake hydrodynamics, the vertical motility of the algae organisms, and the ability of the organisms to form colonies. Here, using the common cyanobacterium Microcystis aeruginosa as an example, we develop a model that accounts for both vertical transport and colony dynamics. At the core of this treatment is a model for aggregation. For this, we used Smoluchowski dynamics containing parameters related to Brownian motion, turbulent shear, differential setting, and cell‐to‐cell adhesion. To arrive at a complete description of bloom formation, we place the Smoluchowski treatment as a reaction term in a set of one‐dimensional advection‐diffusion equations, which account for the vertical motion of the algal cells through molecular and turbulent diffusion and self‐regulating buoyant motion. Results indicate that Smoluchowski aggregation qualitatively describes the colony dynamics of M. aeruginosa. Further, the model demonstrates wind‐induced mixing is the dominant aggregation process, and the rate of aggregation is inversely proportional to algal concentration. Because blooms of Microcystis typically consist of large colonies, both of these findings have direct consequences to harmful algal bloom formation. While the theoretical framework outlined in this manuscript was derived for M. aeruginosa, both motility and colony formation are common among bloom‐forming algae. As such, this coupling of vertical transport and colony dynamics is a useful step for improving forecasts of surface harmful algal blooms. [ABSTRACT FROM AUTHOR]

Harmful algae bloom (HAB) forecasting has developed rapidly over recent decades, but predicting harmful levels of marine biotoxins in shellfish is still a challenge. New discoveries suggest that predator‐prey interactions may be an important driver in the formation of HABs. Key species of harmful algae respond to copepod infochemicals with increased toxin production. In addition, copepods feed selectively on less defended prey, which may further promote harmful taxa. Here we explore if eavesdropping on predator‐prey dynamics by monitoring zooplankton can improve HAB forecasting. We first examine an 8‐yr time series including copepod biomass, harmful algae cells (Dinophysis spp.), and diarrhetic shellfish toxins in blue mussels (Mytilus edulis) using generalized additive models. Models including copepod biomass more accurately predicted okadaic acid in mussels than phytoplankton alone. We then apply this connection more narrowly by analyzing the specific copepod exudates known to induce toxin production, copepodamides, from the mussels sampled in biotoxin monitoring. Adding copepodamide data from shellfish extracts increased model performance compared to copepod biomass. Results suggest that including grazing effects through copepodamide measurements may provide a cost‐efficient way to improve accuracy and lead time for predicting the accumulation of microalgal toxins in shellfish. [ABSTRACT FROM AUTHOR]

Harmful algal blooms (HABs) are common disastrous ecological anomalies in coastal waters. An effective algae monitoring approach is important for natural disaster warning and environmental governance. However, conducting rapid and sensitive detection of multiple algae is still challenging. Here, we designed an ultrasensitive, rapid and portable double-layer microfluidic biochip for the simultaneous quantitative detection of six species of algae. Specific DNA probes based on the 18S ribosomal DNA (18S rDNA) gene fragments of HABs were designed and labeled with the fluorescent molecule cyanine-3 (Cy3). The biochip had multiple graphene oxide (GO) nanosheets-based reaction units, in which GO nanosheets were applied to transfer target DNA to the fluorescence signal through a photoluminescence detection system. The entire detection process of multiple algae was completed within 45 min with the linear range of fluorescence recovery of 0.1 fM–100 nM, and the detection limit reached 108 aM. The proposed approach has a simple detection process and high detection performance and is feasible to conduct accurate detection with matched portable detection equipment. It will have promising applications in marine natural disaster monitoring and environmental care. [ABSTRACT FROM AUTHOR]

The monitoring of harmful phytoplankton is very important for the maintenance of the aquatic ecological environment. Traditional algae monitoring methods require professionals with substantial experience in algae species, which are time-consuming, expensive, and limited in practice. The automatic classification of algae cell images and the identification of harmful phytoplankton images were realized by the combination of multiple convolutional neural networks (CNNs) and deep learning techniques based on transfer learning in this work. Eleven common harmful and 31 harmless phytoplankton genera were collected as input samples; the five CNNs classification models of AlexNet, VGG16, GoogLeNet, ResNet50, and MobileNetV2 were fine-tuned to automatically classify phytoplankton images; and the average accuracy was improved 11.9% when compared to models without fine-tuning. In order to monitor harmful phytoplankton which can cause red tides or produce toxins severely polluting drinking water, a new identification method of harmful phytoplankton which combines the recognition results of five CNN models was proposed, and the recall rate reached 98.0%. The experimental results validate that the recognition performance of harmful phytoplankton could be significantly improved by transfer learning, and the proposed identification method is effective in the preliminary screening of harmful phytoplankton and greatly reduces the workload of professional personnel. [ABSTRACT FROM AUTHOR]

The harmful algal bloom (red tides) (HAB) phenomenon is an issue for desalination facilities. This paper reviews the causes and impacts of HABs on desalination plants. Some HABs are linked to the creation of natural pollutants, dissolved oxygen depletion, and other negative consequences. Because desalination facilities are the principal source of freshwater for communities, agriculture, and industry for middle eastern arid nations, the disruption of plant operations by red tide poses a danger to the availability of drinkable water and can constitute an extraordinary HABs impact. Desalination plants are responsible for pollutants added to the Gulf seawater via outfall systems. Consequently, desalination projects must undergo an environmental impact assessment (EIA), considering accepted environmental characteristics and criteria. EIA assesses the potential effects on air, land, and sea water qualities, techniques to mitigate their impact. [ABSTRACT FROM AUTHOR]

Phytoplankton blooms, including harmful algal blooms (HABs), have serious impacts on ecosystems, public health, and productivity activities. Rapid detection and monitoring of marine microalgae are important in predicting and managing HABs. We developed a toolkit, the Suitcase Lab, to detect harmful algae species in the field. We demonstrated the Suitcase Lab's capabilities for sampling, filtration, DNA extraction, and loop-mediated isothermal amplification (LAMP) detection in cultured Alexandrium catenella cells as well as Chilean coastal waters from four sites: Repollal, Isla García, Puerto Montt, and Metri. A LAMP assay using the Suitcase Lab in the field confirmed microscopic observations of A. catenella in samples from Repollal and Isla García. The Suitcase Lab allowed the rapid detection of A. catenella, within 2 h from the time of sampling, even at a single cell per milliliter concentrations, demonstrating its usefulness for quick and qualitative on-site diagnosis of target toxic algae species. This method is applicable not only to detecting harmful algae but also to other field studies that seek a rapid molecular diagnostic test. [ABSTRACT FROM AUTHOR]

Application of algicidal bacteria is a promising technology to control harmful algal blooms (HABs). In this study, algicidal bacteria strains Shigella sp. H3 and Alcaligenes sp. H5 were obtained via two different isolation methods from the same lake water sample, with optimal algicidal efficiencies 96% and 74% against algae mixture. The Shigella sp. H3 and Alcaligenes sp. H5 lysed algae cells through cells-to-cells direct contact and secretion of algicidal metabolites, respectively. The stronger algicidal capability of Shigella sp. H3 was also attributable to its higher efficiency for triggering reactive oxygen species, which led to broken down of the antioxidant system and more severe damage to the bacterial cells. The antioxidant enzyme activities in Alcaligenes sp. H5 group were still expressed because of its relatively weaker algicidal capability and some intact algal cells were remained. The liquid carbohydrates from algal lysis in both groups increased significantly, whereas the quantities of liquid protein decreased, which might be assimilated by algicidal bacteria. Nonetheless, the whole algicidal process resulted in the increase of total released organic matters content. This study revealed the algicidal pathways of diverse bacterial strains, and the possible secondary environmental problem caused by the algal released organic matters should be considered when applying bacteria to control HABs. [ABSTRACT FROM AUTHOR]

Harmful algal bloom (HAB) species Alexandrium catenella and Dinophysis acuminata are associated with paralytic shellfish poisoning (PSP) and diarrhetic shellfish poisoning (DSP) in humans, respectively. While PSP and DSP have been studied extensively, less is known about the effects of these HAB species or their associated toxins on shellfish. This study investigated A. catenella and D. acuminata toxicity in a larval oyster (Crassostrea virginica) bioassay. Larval activity and mortality were examined through 96-h laboratory exposures to live HAB cells (10–1000 cells/mL), cell lysates (1000 cells/mL equivalents), and purified toxins (10,000 cells/mL equivalents). Exposure to 1000 cells/mL live or lysed D. acuminata caused larval mortality (21.9 ± 7.0%, 10.2 ± 4.0%, respectively) while exposure to any tested cell concentration of live A. catenella, but not lysate, caused swimming arrest and/or mortality in >50% of larvae. Exposure to high concentrations of saxitoxin (STX) or okadaic acid (OA), toxins traditionally associated with PSP and DSP, respectively, had no effect on larval activity or mortality. In contrast, pectenotoxin-2 (PTX2) caused rapid larval mortality (49.6 ± 5.8% by 48 h) and completely immobilized larval oysters. The results indicate that the toxic effects of A. catenella and D. acuminata on shellfish are not linked to the primary toxins associated with PSP and DSP in humans, and that PTX2 is acutely toxic to larval oysters. [ABSTRACT FROM AUTHOR]

The deployment of Remote Monitoring Systems (RMS) based on Internet of Things (IoT) technologies and data management in the cloud is a cutting-edge solution for water management agencies to track harmful algae blooms (HABs). However, each environment presents different intrinsic characteristics, hence the reliability and representativeness of collected data may vary according to the selected RMS architecture. This study aims to implement the same RMS in two different water bodies in Spain: the freshwater As Conchas reservoir and the shallow L’Albufera brackish water lagoon. We firstly evaluate the pros and cons of current technologies available on the market and then we select an RMS based on a combination of plug-and-play (YSI-based) and customisable solutions (Libelium-based). The deployment of nodes on buoys allows big data collection from different areas of water bodies, their continuous transfer and storage on a web server, and their subsequent visualisation on the web interface in real time. Secondly, in order to know whether the selected RMS architecture and monitored environment influence the representativeness of the collected data, we perform a Pearson correlation test between the deployed nodes and satellite images. The results point out that the more heterogeneous the environment is, the more nodes must be deployed in different areas for a longer time to obtain a realistic view of the water body status. Therefore, this study provides critical and empirical data to implement a profitable and effective real-time monitoring system in other HAB-affected areas. [ABSTRACT FROM AUTHOR]

Germination of cysts serves as inoculum for the proliferation of some dinoflagellates, and cyst abundance in sediments represents crucial information to understand and possibly predict Harmful Algae Blooms (HABs). Cyst distribution is related to the physical characteristics of the sediments and the hydrodynamics (circulation) of a particular region. In the northern Gulf of California (nGC) several Gymnodinium catenatum HABs have been recorded. However, the presence of resting cysts and the effect of hydrodynamics on their distribution in the nGC have not been investigated. This study evaluated cyst abundance, distribution and their relation to local circulation in surface sediments during two periods that coincided with a non-bloom year condition (July 2016) and after a major HAB registered in the nGC that occurred in January 2017. Also, a numerical ocean model was implemented to characterize the transport and relocation of cysts and sediments in the region. Gymnodinium catenatum cysts were heterogeneously distributed with some areas of high accumulation (as high as 158 cyst g−1, and 27% of total cyst registered). Cysts seemed to be transported in an eastward direction after deposition and accumulated in an extensive area that probably is the seedbed responsible for the initiation of HABs in the region. The nGC is a retention area of cysts (and sediments) that permit the formation of seedbeds that could be important for G. catenatum HAB development. Our results provide key information to understand G. catenatum ecology and specifically, to understand the geographic and temporal appearance of HABs in the nGC. [ABSTRACT FROM AUTHOR]

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Herbivores play an essential role in the health and recovery of a coral reef ecosystem. The lack of recovery of the keystone herbivore Diadema antillarum has had long‐lasting effects, evidenced with many reefs persisting in algal dominance. This study restocked 756 lab‐reared D. antillarum to four coral reefs on the east and south coast of Puerto Rico. Sea urchins were placed in experimental plots ("corrals") for 2 months, and the change in benthic composition was measured. Significant changes in the benthic structure were observed during the first week after the restocking. Significant reductions of fleshy macroalgae (Dictyota spp.) and thick turf algal/sediment mats (TAS), both unsuitable substrates (e.g. coral settlement), contributed to this change. Also, restocked D. antillarum significantly reduced the cover of encrusting red algae, Ramicrusta spp. By the end of the study, the abundance of fleshy macroalgae decreased by a mean of 77% (max of 100%) and Ramicrusta and TAS by 53% (max 71%) and 56% (max 100%), respectively. Clean substrate ("pavement"), crustose coralline algae (CCA), and filamentous turf algae increased between one to two orders of magnitude. The restoration of native sea urchins is a non‐invasive and useful approach to aid in the mitigation of algae, especially potentially dangerous alga like Ramicrusta. The results of this study highlight the importance of herbivores in improving the conditions on coral reefs. [ABSTRACT FROM AUTHOR]

Global ocean change threatens marine life, yet a mechanistic understanding of how organisms are affected by specific stressors is poorly understood. Here, we identify and compare the unique and common transcriptomic responses of an organism experiencing widespread fisheries declines, Argopecten irradians (bay scallop) exposed to multiple stressors including high pCO2, elevated temperature, and two species of harmful algae, Cochlodinium (aka Margalefidinium) polykrikoides and Aureococcus anophagefferens using high‐throughput sequencing (RNA‐seq). After 48 hr of exposure, scallop transcriptomes revealed distinct expression profiles with larvae exposed to harmful algae (C. polykrikoides and A. anophagefferens) displaying broader responses in terms of significantly and differentially expressed (DE) transcripts (44,922 and 4,973; respectively) than larvae exposed to low pH or elevated temperature (559 and 467; respectively). Patterns of expression between larvae exposed to each harmful algal treatment were, however, strikingly different with larvae exposed to A. anophagefferens displaying large, significant declines in the expression of transcripts (n = 3,615; 87% of DE transcripts) whereas exposure to C. polykrikoides increased the abundance of transcripts, more than all other treatments combined (n = 43,668; 97% of DE transcripts). Larvae exposed to each stressor up‐regulated a common set of 21 genes associated with protein synthesis, cellular metabolism, shell growth, and membrane transport. Larvae exposed to C. polykrikoides displayed large increases in antioxidant‐associated transcripts, whereas acidification‐exposed larvae increased abundance of transcripts associated with shell formation. After 10 days of exposure, each harmful algae caused declines in survival that were significantly greater than all other treatments. Collectively, this study reveals the common and unique transcriptional responses of bivalve larvae to stressors that promote population declines within coastal zones, providing insight into the means by which they promote mortality as well as traits possessed by bay scallops that enable potential resistance. [ABSTRACT FROM AUTHOR]

The mathematical concept of multiplier robust control is applied to a dam operation problem, which is an urgent issue on river water environment, as a new industrial application of stochastic optimal control. The goal of the problem is to find a fit‐for‐purpose and environmentally sound operation policy of the flow discharge from a dam so that overgrowth of the harmful algae Cladophora glomerata Kützing in its downstream river is effectively suppressed. A minimal stochastic differential equation for the algae growth dynamics with uncertain growth rate is first presented. The performance index to be maximized by the operator of the dam while minimized by nature is formulated within the framework of differential games. The dynamic programming principle leads to a Hamilton‐Jacobi‐Bellman‐Isaacs equation whose solution determines the worst‐case optimal operation policy of the dam, ie, the policy that the operator wants to find. Application of the model to overgrowth suppression of Cladophora glomerata Kützing just downstream of a dam in a Japanese river is then carried out. Values of the model parameters are identified with which the model successfully reproduces the observed population dynamics. A series of numerical experiments are performed to find the most effective operation policy of the dam based on a relaxation of the current policy. [ABSTRACT FROM AUTHOR]

Cyanobacterial harmful algal blooms (CyanoHABs) are increasingly being reported worldwide owing to several reasons, including widespread eutrophication and enhanced scientific monitoring. Catchment and water management, organisations, industry, farmers and local governments are all confronting the effects of climate change, which stimulate the growth of cyanobacteria and affect the efficacy of adaptation measures in water systems. To tackle climate change and CyanoHABs growth, actors at different levels require both 'top-down' and 'bottom-up' assessments to help them in formulating and implementing adaptation measures. Potential solutions must also be assessed locally to limit associated adverse effects, in particular, negative effects on water quality. Thus, having a better understanding of the synergies, conflicts and trade-offs between adaptation practices and climate-change effects on CyanoHABs makes a valuable contribution to a more integrated climate policy and the effective climate-proofing of our water bodies. This article examines adaptation practices focused on tackling CyanoHABs occurrence in a changing climate. It fills an important gap between a major environmental problem and potential solutions. The practices and measures advanced as a result of the analysis can be used by persons with different expertise and skill levels for improving the relevant institutional frameworks and policies to protect their local water bodies. The vulnerability of water resources to the impacts of climate change is not simply determined by geographic location. It is also influenced by how water users and local communities are coping with climate-change impacts. This article examines adaptation practices focused on tackling CyanoHABs occurrence in developing economies under changing climate. [ABSTRACT FROM AUTHOR]

To evaluate how the decay of bloom-forming algae affect the coastal dissolved oxygen, a laboratory simulation was conducted in terms of three typical harmful algae, Alexandrium catenella, Prorocentrum donghaiense, and Skeletonema costatum. Algae of same biomass (55 μg/mL) were conducted in lightproof columns, and the cell density, dissolved oxygen (DO), and ammonia nitrogen of different layers were monitored at certain time series. Results show that the decomposition of algae significantly decreased the DO, and increased the ammonia nitrogen in all layers; and significant deference between different species was observed. The A. catenella treatment showed the lowest DO (average concentration of 3.4 mg/L) and the highest ammonia nitrogen (average concentration of 0.98 mg/L) at the end of test, followed by P. donghaiense; and the S. costatum showed relatively high DO and low ammonia nitrogen due to slow decay rate. Results indicate that decomposition of harmful bloom algae, especially dinoflagellate, would cause significantly DO depletion and toxic ammonia nitrogen increase, which will detrimentally affect both pelagic and benthic ecosystem. [ABSTRACT FROM AUTHOR]

Harmful algal blooms (HABs) are a naturally occurring global phenomena that have the potential to impact fisheries, leisure and ecosystems, as well as posing a significant hazard to animal and human health. There is significant interest in the development and application of methodologies to study all aspects of the causative organisms and toxins associated with these events. This paper reports the first application of nanopore sequencing technology for the detection of eukaryotic harmful algal bloom organisms. The MinION sequencing platform from Oxford Nanopore technologies provides long read sequencing capabilities in a compact, low cost, and portable format. In this study we used the MinION to sequence long-range PCR amplicons from multiple dinoflagellate species with a focus on the genus Alexandrium. Primers applicable to a wide range of dinoflagellates were selected, meaning that although the study was primarily focused on Alexandrium the applicability to three additional genera of toxic algae, namely; Gonyaulax , Prorocentrum , and Lingulodinium was also demonstrated. The amplicon generated here spanned approximately 3 kb of the rDNA cassette, including most of the 18S, the complete ITS1, 5.8S, ITS2 and regions D1 and D2 of the 28S. The inclusion of barcode genes as well as highly conserved regions resulted in identification of organisms to the species level. The analysis of reference cultures resulted in over 99% of all sequences being attributed to the correct species with an average identity above 95% from a reference list of over 200 species (see Supplementary Material 1). The use of mock community analysis within environmental samples highlighted that complex matrices did not prevent the ability to distinguish between phylogenetically similar species. Successful identification of causative organisms in environmental samples during natural toxic events further highlighted the potential of the assay. This study proves the suitability of nanopore sequencing technology for taxonomic identification of harmful algal bloom organisms and acquisition of data relevant to the World Health Organisations "one health" approach to marine monitoring. [ABSTRACT FROM AUTHOR]

The Phaeocystis globosa widely exists in the seawater, which becomes a great threat for the health of humans and animals in the ecological ecosystem. In this work, we reported a promising control strategy with quercetin(QT) enhanced cellulose nanocrystals (CNC). The quercetin enhanced cellulose nanocrystals (QT/CNC) was characterized through Atomic Force Microscopy (AFM), Fourier Transform Infrared Spectrometer (FTIR) and X-ray diffractometer (XRD). The effects of concentrations of CNC and QT on controlled Phaeocystis globosa were investigated. The results showed that the removal rate of Phaeocystis globosa exhibited an optimal value (92.1 %) at 0.05 g L-1 CNC and 0.1 g L-1 QT. Furthermore, the chlorophyll-a content in the Phaeocystis globosa exhibited a remarkable decrease from 3.72 mg L−1 to 0.21 mg L−1 when QT/CNC was interacted. On the basis of these results, we concluded that Phaeocystis globosa could be removed by QT/CNC effectively. During the removal of Phaeocystis globosa, the pH of algal solution decreased from 9.45 to 7.36, indicating that QT/CNC could maintain the normal pH of water. In addition, the testing result of the QT/CNC zeta potentials was negative, which revealed that Phaeocystis globosa was removed through inhibition and flocculation. Accordingly, a possible removal mechanism of Phaeocystis globose by QT/CNC was presumed. This study suggested that QT/CNC might be a potential treatment materials on the removal of Phaeocystis globosa. [ABSTRACT FROM AUTHOR]

Photocatalysis has attracted much attention as an emerging algae removal technology, but the inactivation performance is inevitably affected by the extracellular polymeric substance (EPS) produced by algae. In this study, a photocatalyst (Ag2O/g‐C3N4) with efficient algae inactivation is adopted to investigate the interactions with EPS, and the impact of EPS on photocatalytic algae removal is studied. The results show that EPS can adhere to the surface of Ag2O/g‐C3N4 by electrostatic force. The interaction with EPS decreases the surface zeta potential of the Ag2O/g‐C3N4 from 7.71 to −22.3 mV with the increase in EPS concentration, and the maximum ratio of particle size increases from 825 to 1281 nm. In addition, the interaction with EPS inhibits the release of Ag+ in Ag2O/g‐C3N4 by half, thus, the toxicity of metal ions will be alleviated. Meanwhile, EPS can also be degraded by Ag2O/g‐C3N4, indicating that EPS can work as a radical scavenger to protect the algae cells. Without the protection of EPS, 97.8% of algae cells are inactivated after 5 h photocatalysis. Therefore, more attention should be given to the interaction between EPS and photocatalyst to promote the design and application of the photocatalytic. [ABSTRACT FROM AUTHOR]

Harmful algal blooms have become a great challenge to global aquatic ecosystems over the past decades. Given their low toxicity, high selectivity, and environment-friendly properties, the use of natural products and their analogues as algicides has proven to be particularly efficient. In the present study, algicidal activity of naturally occurring bacillamides A-C, alkaloid (1), and neobacillamide A, as well as their synthetic analogues were investigated intensively. Bioassay results showed that, relative to natural bacillamide alkaloids, aniline-derived analogue (10d) exhibited higher algicidal potential against three freshwater harmful algae Mycrocyctis aeruginosa, Scenedesmus obliquus, and Chlorella pyrenoidosa, suggesting that it could be used as a promising lead compound to develop novel algicide for controlling harmful algal blooms. [ABSTRACT FROM AUTHOR]

Harmful algae blooms are a rare phenomenon in rivers but seem to increase with climate change and river regulation. To understand the controlling factors of cyanobacteria blooms that occurred between 2017 and 2020 over long stretches (> 250 km) of the regulated Moselle River in Western Europe, we measured physico-chemical and biological variables and compared those with a long-term dataset (1997–2016). Cyanobacteria (Microcystis) dominated the phytoplankton community in the late summers of 2017–2020 (cyano-period) with up to 110 µg Chlorophyll-a/L, but had not been observed in the river in the previous 20 years. From June to September, the average discharge in the Moselle was reduced to 69–76% and water temperature was 0.9–1.8 °C higher compared to the reference period. Nitrogen (N), phosphorus (P) and silica (Si) declined since 1997, albeit total nutrient concentrations remained above limiting conditions in the study period. Cyanobacterial blooms correlated best with low discharge, high water temperature and low nitrate. We conclude that the recent cyanobacteria blooms have been caused by dry and warm weather resulting in low flow conditions and warm water temperature in the regulated Moselle. Under current climate projections, the Moselle may serve as an example for the future of regulated temperate rivers. [ABSTRACT FROM AUTHOR]

Harmful algal blooms recently have been under the spotlight throughout the world, because of their negative impact on the marine environment, aquaculture, fisheries as well as public health. The development of methods for rapid and precise identification and quantification of causative species is essential for the warning andmonitoring of blooms, among which the techniques based on taxonomic probes are themost favored. In this study, two harmful algae, i.e., Prorocentrum minimum and Karenia mikimotoi were taken into consideration. The partial large subunit rDNA (D1-D2) of both species were firstly PCR-amplified, cloned and sequenced. The obtained sequences were then introduced to carry out alignment analysis for gene specific regions. Three respective candidate probes for each species were designed and used to screen the optimal probe by performing fluorescence in situ hybridization (FISH) tests. The results showed that the probes Pmin0443 and Kmik0602 displayed the best hybridization for P. minimum and K. mikimotoi, respectively. Both the specific (taxonomic) (Pmin0443 and Kmik0602) and the control probes (UniC0512 and UniR0499) were used for cross-reactivity tests with other microalgae in our laboratory. The probes Pmin0443 and Kmik0602 are specific and could be served as taxonomic probes introduced into the techniques targeting rRNA, such as FISH, sandwich hybridization, and DNA-microarray assay of P. minimum and K. mikimotoi in the future. Finally, FISH analyses with both probes were performed on the simulated field samples. The probes could hybridize exclusively with the target cells well, and no significant difference ( p >0.05) was observed in the cell densities of the samples determined by FISH and light microscopy (LM). All suggest that the probes are specific and could be introduced into FISH for the monitoring of both harmful algae. [ABSTRACT FROM AUTHOR]

Harmful algae and cyanobacteria blooms are increasing in frequency and intensity in freshwater systems due to anthropogenic impacts such as nutrient loading in watersheds and engineered alterations of natural waterways. There are multiple physical factors that affect the conditions in a freshwater system that contribute to optimal habitats for harmful algae and toxin-producing cyanobacteria. A growing body of research shows that climate change stressors also are impacting water-body conditions that favor harmful algae and cyanobacteria species over other phytoplankton. The overgrowth of these organisms, or a "bloom," increases the opportunity for exposure to toxins by humans, companion animals, livestock, and wildlife. As waters warm and precipitation patterns change over time, exposure to these blooms is projected to increase. Hence, it is important that states and tribes develop monitoring and reporting strategies as well as align governmental policies to protect their citizens and ecosystems within their jurisdiction. Currently, the policies and approaches taken to monitor and report on harmful algae and cyanobacteria blooms vary widely among states, and it is undetermined if any tribes have specific policies on harmful algae blooms. This paper synthesizes research on algal blooms in inland freshwater systems of the United States. This review examines how climate change contributes to trends in bloom frequency or severity and outlines approaches that states and tribes may use to monitor, report, and respond to harmful algae and cyanobacteria blooms. Significance Statement: Inland bodies of freshwater supply drinking water for humans and animals, water for irrigating crops, habitats for aquatic species, places of cultural significance for Indigenous peoples, and other important functions. Many of these bodies of water have been polluted with runoff from industry, including agriculture, and already support harmful algal blooms during warm conditions. Hot extremes associated with climate change are expected to increase the occurrence and duration of harmful algal blooms, and in some places, initiate blooms where none have been recorded previously. These toxic blooms are harmful to people, companion animals, livestock, and wildlife. It is important to review the interconnections among biological, climate, and water systems to monitor blooms and alert the public about their toxin production. [ABSTRACT FROM AUTHOR]

Elevated pCO2 and warming may promote algal growth and toxin production, and thereby possibly support the proliferation and toxicity of harmful algal blooms (HABs). Here, we tested whether empirical data support this hypothesis using a meta‐analytic approach and investigated the responses of growth rate and toxin content or toxicity of numerous marine and estuarine HAB species to elevated pCO2 and warming. Most of the available data on HAB responses towards the two tested climate change variables concern dinoflagellates, as many members of this phytoplankton group are known to cause HAB outbreaks. Toxin content and toxicity did not reveal a consistent response towards both tested climate change variables, while growth rate increased consistently with elevated pCO2. Warming also led to higher growth rates, but only for species isolated at higher latitudes. The observed gradient in temperature growth responses shows the potential for enhanced development of HABs at higher latitudes. Increases in growth rates with more CO2 may present an additional competitive advantage for HAB species, particularly as CO2 was not shown to enhance growth rate of other non‐HAB phytoplankton species. However, this may also be related to the difference in representation of dinoflagellate and diatom species in the respective HAB and non‐HAB phytoplankton groups. Since the proliferation of HAB species may strongly depend on their growth rates, our results warn for a greater potential of dinoflagellate HAB development in future coastal waters, particularly in temperate regions. [ABSTRACT FROM AUTHOR]

Warning and monitoring projects of harmful algal blooms require simple and rapid methods for simultaneous and accurate detection and identification of causative algae present in the environmental samples. Here, reverse dot blot hybridization (RDBH) was employed to simultaneously detect several harmful algae by using five representative bloom-forming microalgae along the Chinese coast. A set of specific probes for RDBH were developed by PCR, cloning, and sequencing of the internal transcribed spacer (ITS), alignment analysis, and probe design. Each probe was oligo (dT)-tailed and spotted onto positively charged nylon membrane to make up a low-density oligonucleotide array. Universal primers designed within the conserved regions were used to amplify the ITS sequences by using genomic DNA of target as templates. The digoxigenin (Dig)-labeled PCR products were denatured and then hybridized to the oligonucleotide array. The array produced a unique hybridization pattern for each target species differentiating them from each other. The preparations of oligonucleotide array and hybridization conditions were optimized. The developed RDBH demonstrated a detection limit up to 10 cells. The detection performance of RDBH was relatively stable and not affected by non-target species and the fixation time of target species over at least 30 days. The RDBH could recover all the target species from the simulated field samples and target species confirmed by the subsequent microscopy examination in the environmental samples. These results indicate that RDBH can be a new technical platform for parallel discrimination of harmful algae and is promising for environmental monitoring of these microorganisms. [ABSTRACT FROM AUTHOR]

Resting strategies of planktonic organisms are important for the ecological processes of coastal waters and their impacts should be taken into consideration in management of water bodies used by multiple industries. We combined different approaches to evaluate the importance of resting stages in Singapore coastal waters. We used molecular approaches to improve the knowledge on Singapore biodiversity, we sampled and extracted cysts from sediments to evaluate the density of resting stages in Johor Strait, and we compared systematically information on Singapore planktonic biodiversity to existing published information on resting stages from these reported organisms. This is the first study evaluating the importance of resting stages in Singapore waters. Above 120 species reported in Singapore are known to produce resting stages though no previous work has ever been done to evaluate the importance of these strategies in these waters. The results from the resting stage survey confirmed 0.66 to 5.34 cyst g−1 dry weight sediment were present in the Johor Strait suggesting that cysts may be flushed by tidal currents into and out of the strait regularly. This also suggest that the blooms occurring in Singapore are likely due to secondary growth of Harmful Algae Bloom species in the water rather than from direct germination of cysts from sediment. Finally, we discuss the importance of these resting eggs for three main national industries in Singapore (shipping, marine aquaculture and provision of drinking water through seawater desalination). We argue that this study will serve as a baseline for some of the future management of Singapore waters. [ABSTRACT FROM AUTHOR]

Cyanobacteria are found globally due to their adaptation to various environments. The occurrence of cyanobacterial blooms is not a new phenomenon. The bloom-forming and toxin-producing species have been a persistent nuisance all over the world over the last decades. Evidence suggests that this trend might be attributed to a complex interplay of direct and indirect anthropogenic influences. To control cyanobacterial blooms, various strategies, including physical, chemical, and biological methods have been proposed. Nevertheless, the use of those strategies is usually not effective. The isolation of natural compounds from many aquatic and terrestrial plants and seaweeds has become an alternative approach for controlling harmful algae in aquatic systems. Seaweeds have received attention from scientists because of their bioactive compounds with antibacterial, antifungal, anti-microalgae, and antioxidant properties. The undesirable effects of cyanobacteria proliferations and potential control methods are here reviewed, focusing on the use of potent bioactive compounds, isolated from seaweeds, against microalgae and cyanobacteria growth. [ABSTRACT FROM AUTHOR]

Phaeocystis globosa blooms can have negative effects on higher trophic levels in the marine ecosystem and consequently influence human activities. Strain KA22, identified as the bacterium Hahella, was isolated from coastal surface water and used to control P. globosa growth. A methanol extract from the bacterial cells showed strong algicidal activity. After purification, the compound showed a similar structure to prodigiosin when identified with Q-Exactive Orbitrap MS and nuclear magnetic resonance spectra. The compound showed algicidal activity against P. globosa with a 50% Lethal Dose (LD50) of 2.24 µg/mL. The prodigiosin was stable under heat and acid environment, and it could be degraded under alkaline environment and natural light condition. The growth rates of strain KA22 was fast in 2216E medium and the content of prodigiosin in this medium was more than 70 µg/mL after 16 h incubation. The compound showed particularly strong algicidal activity against Prorocentrum donghaiense, P. Globosa, and Heterosigma akashiwo, but having little effect on three other phytoplankton species tested. The results of our research could increase our knowledge on harmful algal bloom control compound and lead to further study on the mechanisms of the lysis effect on harmful algae. [ABSTRACT FROM AUTHOR]