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Purpose: This study investigates the regulatory role of NL13, a compound derived from adenosyl homocysteinase of cyanobacteria, on ER stress-induced apoptosis in endothelial cells by modulating the Keap1-Nrf2 signaling pathway. Methods: Human endothelial cells (EA.hy926) were exposed to thapsigargin (TPG) to induce ER stress and then pretreated with varying concentrations of NL13. The study employed qPCR to assess changes in gene expression related to ER stress markers (GRP78, CHOP, ATF6, and PERK) and Nrf2. Additionally, reactive oxygen species (ROS) levels and the expression of apoptotic proteins (Bcl2 and Bax) were evaluated. In-silico molecular docking was used to explore potential interactions between NL13 and Keap1-Nrf2. Results: NL13 significantly reduced oxidative and ER stress in endothelial cells. It downregulated ER stress markers (GRP78, CHOP, ATF6, PERK) while upregulating Nrf2 expression. NL13 also decreased ROS formation and modulated the expression of apoptotic proteins, increasing Bcl2 and decreasing Bax. Molecular docking revealed interactions of NL13 with critical amino acids in Keap1-Nrf2, suggesting a functional binding that enhances Nrf2 signaling. Conclusion: NL13 exerts cytoprotective effects against ER stress in endothelial cells by modulating the Keap1-Nrf2 signaling pathway and reducing apoptosis. These findings highlight the potential of NL13 as a therapeutic agent for conditions involving ER stress and oxidative damage. [ABSTRACT FROM AUTHOR]

Tremendous potential in the field of anti-biofouling coatings to prevent stainless steel (SS)-based underwater pipelines, sea vessels and other marine structures have been recognized to protect from biofouling, which is often initiated by algae attachment over the surface. In this work, hydrophobicity in spray-pyrolysed tungsten oxide (TO) coating on SS-316 substrate has been reported for the first time, via post-processing treatment using octadecyltrimethoxysilane (ODTMS) to induce self-assembled monolayer (SAM). Initially, structural and vibrational characteristics of ODTMS and ODTMS-treated TO (OTO) coating on SS were analysed using X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopies. OTO-coating depicted a water contact angle (WCA) of 121°, revealing its hydrophobic nature, with further affirmation from X-ray photoelectron spectroscopy (XPS). Durability of the TO-coating was explored using the scratch hardness (Hs) test at different loading conditions (5, 10 and 15 N). Biofouling study was conducted by culturing blue-green algae (BGA, Phormidium sp.) in an in-house laboratory setup for 40 days, using seawater (collected from the Arabian Sea, Karnataka). The SS, TO- and OTO-coatings were immersed for 14 days in a controlled sea-water environment in the laboratory with the presence of BGA. A comparative study on the areal-algae attachment was keenly analysed over SS-, TO- and OTO-coatings. This work can be projected as a promising application providing multi-dimensional solutions in creating scratch-resistant and anti-biofouling coatings on SS in the shipbuilding industry. [ABSTRACT FROM AUTHOR]

This study investigates the synthesis and characterization of a novel chitosan–blue-green algae (BGA) composite adsorbent for the efficient removal of Acid Red 73 (AR73) dye from wastewater. The composite was characterized using Fourier transform infrared, zeta potential, an energy-dispersive X-ray analysis, and scanning electron microscopy analyses, revealing the presence of functional groups crucial for dye adsorption and a rough surface morphology indicative of high surface area. Batch adsorption experiments were conducted to evaluate the influence of pH, adsorbent dosage, contact time, and initial dye concentration on AR73 removal. The composite exhibited optimal adsorption at pH 6, with increasing removal efficiency observed with increasing adsorbent dosage and contact time until equilibrium was reached. The adsorption process followed pseudo-second-order kinetics, suggesting chemisorption as the dominant mechanism. In addition, the Freundlich isotherm model best described the adsorption process, suggesting a heterogeneous adsorption mechanism. The composite demonstrated good adsorption capacity (Qm = 142.86 mg/g) in the Langmuir model. The thermodynamic data strongly indicate that the removal process occurs through a physisorption process, and endothermic. Furthermore, the composite demonstrated photocatalytic activity under direct sunlight, effectively degrading AR73 dye and achieving complete removal at higher initial concentrations. The reusability of the composite was also investigated, showing sustained removal efficiency over two cycles, but a significant decrease in the third cycle. Finally, the application of the composite in treating aquaculture wastewater resulted in significant improvements in water quality parameters, including reduced turbidity, nitrate levels, and salinity. This study highlights the potential of the chitosan–BGA composite as a sustainable and efficient adsorbent and photocatalyst for dye removal and wastewater treatment. [ABSTRACT FROM AUTHOR]

The phenomenon of cyanobacterial bloom, among other things, is chronic and periodic pollution, which is mainly caused by phosphorus and nitrogen, as well as high temperatures and direct sunlight. To carry out this experiment, in order to obtain blooming cyanobacteria in the warm water pond fish, water samples were taken from 5 farms and after purification, mass culture of 4 species of cyanobacteria that had the highest density was prepared. Then kaolin with a concentration of 0.5 g/liter and separately with two sizes of 50 and 100 micrometers was added to the pure culture of any cyanobacteria species using a 1-meter column. The amount of reduction of cyanobacteria was checked by counting by Neubauer chamber at 0, 3, 9 and 24 hours after adding to it. The results showed the decrease in the number of cyanobacteria Chroococcus sp. For kaolin with two sizes of 100 and 50 micrometers, it was 24.4 and 39%, respectively. This rate was 25.8 and 15.5% for the cyanobacterium Gloeocapsa sp. Also, for cyanobacterium Oscillatoria sp., 23.5 and 35.3% were calculated and finally for cyanobacterium Microcystis sp., 29.4 and 33.3% were calculated. The results of this research showed that the separate use of two sizes of kaolin, 100 and 50 micrometers, is effective for the immediate control of cyanobacterial bloom, and also, comparing the two sizes of kaolin, kaolinite with the size of 50 micrometers had better operation. [ABSTRACT FROM AUTHOR]

Heavy metals such as mercury (Hg) can cause disturbances in the metabolic and phycoremediation activities of microalgae. γ-aminobutyric acid or GABA is a non-protein amino acid and has a signaling role that can regulate the homeostasis of reactive oxygen species (ROS) under environmental stress. In this research, the effect of exogenous GABA on the physiological responses of blue-green algae (cyanobacterium) Spirulina platensis under mercury stress was investigated. HgCl2 in 4 and 8 μM, and GABA in 2 and 4 mM, individually and as a combined treatment, were applied to the microalgal cell suspensions for 48 hours. Then, the indices; dry weight, chlorophyll a, carotenoid, phycobilins, phenol, carbohydrate, protein, malondialdehyde, and polyphenol oxidase and peroxidase activities were evaluated. HgCl2 treatment (individually) decreased dry weight, chlorophyll a, carotenoid, phycoerythrin, phenol, carbohydrate and protein compared to those in control and increased the level of lipid peroxidation and the activities of polyphenol oxidase and peroxidase enzymes. Single treatment of GABA increased dry weight, phycobilin, phenol, malondialdehyde, protein and enzyme activity. But the combined treatments (GABA + HgCl2) improved most of the physiological indices. HgCl2 treatment in one or both concentrations caused a negative effect on the physiological indicators of Spirulina platensis and decreased metabolites such as phenol and proteins, but GABA treatment in most cases reduced the negative effects of mercury and improved the indices. According to the literature, Hg toxicity can be caused by disrupting the biosynthesis of photosynthetic pigments and the activity of enzymes and the occurrence of oxidative stress. While, exogenous GABA can improve the metabolic and physiological cell condition as a signaling molecule through the occurrence of some intracellular events. [ABSTRACT FROM AUTHOR]

Commercially produced cyanobacteria preparations sold under the name spirulina are widely consumed, due to their traditional use as a nutrient-rich foodstuff and subsequent marketing as a superfood. Despite their popularity, the microbial composition of ponds used to cultivate these bacteria is understudied. A total of 19 pond samples were obtained from small-scale spirulina farms and subjected to metagenome and/or virome sequencing, and the results were analysed. A remarkable level of prokaryotic and viral diversity was found to be present in the ponds, with Limnospira sp. and Arthrospira sp. sometimes being notably scarce. A detailed breakdown of prokaryotic and viral components of 15 samples is presented. Twenty putative Limnospira sp.-infecting bacteriophage contigs were identified, though no correlation between the performance of these cultures and the presence of phages was found. The high diversity of these samples prevented the identification of clear trends in sample performance over time, between ponds or when comparing successful and failed fermentations. [ABSTRACT FROM AUTHOR]

This study aimed to reduce the occurrence of algal blooms by decreasing nitrogen and phosphorus elution leaked from livestock manure sprayed on farmland in dams and river basins. Excessive algal growth affects water availability by disturbing the aquatic ecosystem, clogging filters of the water intake tower, generating toxins, and causing social and economic losses. Nutrients discharged from nonpoint pollution sources (farmlands and barns) often flow into rivers without being purified, thus contaminating nearby river basins. An analysis of algal growth characteristics by dividing rainfall runoff into raw solution, nitrogen and phosphorus adsorbent (NPA) compost, and general compost affected growth rate and microalgae biomass production as well as nitrogen and phosphorus removal rates. Blue-green algae (Microcystis aeruginosa) and green algae (Scenedesmus acutus) were diluted, and the effect of reduction of microalgae growth was studied in all experiments. Results of water quality analysis reveal that eco-friendly compost has the effect of reducing nutrient salts in rainfall runoff by 30%-40% compared to general compost. Furthermore, the growth of blue-green algae and green algae can be reduced if the effluent of eco-friendly compost flows into the river and the nutrient concentration is lowered. [ABSTRACT FROM AUTHOR]

Harmful Algal Blooms (HABs) are outbreaks of aquatic toxic microalgae emerging as a global problem driven by nutrient enrichment, global climate change and invasive species. We uniquely describe a HAB of unprecedented duration, extent and magnitude during 2023 in Lough Neagh; the UK and Ireland’s largest freshwater lake, using an unparalleled combination of satellite imagery, nutrient analysis, 16S rRNA gene sequencing and cyanotoxin profiling. The causative agent Microcystis aeruginosa accounted for over a third of DNA in water samples though common bacterioplankton species also bloomed. Water phosphate levels were hypertrophic and drove local algal biomass. The HAB pervaded the entire ecosystem with algal mats accumulating around jetties, marinas and lock gates. Over 80 % of bacterial DNA isolated from algal mat samples consisted of species associated with wildfowl or livestock faeces and human-effluent wastewater including 13 potential pathogens that can cause serious human illness including: E. coli, Salmonella, Enterobacter and Clostridium among others. Ten microcystins, nodularin and two anabaenopeptin toxins were confirmed as present (with a further microcystin and four anabaenopeptins suspected), with MC-RR and -LR in high concentrations at some locations (1,137–18,493 μg/L) with MC-LR exceeding World Health Organisation (WHO) recreational exposure guidelines in all algal mats sampled. This is the first detection of anabaenopeptins in any waterbody on the island of Ireland. Notwithstanding the ecological impacts, this HAB represented an environmental and public health risk, curtailing recreational activities in-and-around the lake and damaging local businesses. Reducing agricultural runoff and discharge from human-effluent wastewater treatment to manage nutrient loading, and the public health risk, should be the top priority of stakeholders, especially government. Key recommendations include Nature-based Solutions that avoid conflict with the productivity and profitability of the farming sector enhancing sustainability. We hope this stimulates real-world action to resolve the problems besetting this internationally important ecosystem.

The research presents the results of remote monitoring of blue-green algae of the Kuibyshev reservoir, leading to eutrophication of the reservoir. Multispectral images were taken by the European Space Agency’s Sentinel-2 remote sensing satellite and were processed by using QGIS software. Satellite images were processed using spectral indices. After using several spectral indices, the three most informative ones were selected: NDVI, NDWI and SIPI. The usage of processed images made it possible to define the boundaries of the distribution of blue-green algae more clearly, as well as the zones of the most intensive development of biomass. The use of several spectral indices made it possible to determine the most suitable data for the usage under adverse meteorological conditions. The analysis of the processed satellite images makes it possible to assess the intensity of the development of blue-green algae. This is the basis for the development of a forecast model of biomass changes in the reservoirs of the middle zone of the Russian Federation.

The application of modern molecular methods and phylogenetic approaches saw an explosion in cyanobacterial taxonomy in the first two decades of the twenty-first century. The relative ease of description of new taxa and the pressure to publish a high number of scientific papers has created apparent confusion. The situation is particularly complicated for ecologically oriented limnological research and practical hydrobiologists especially have numerous criticisms of this trend. On closer observation, however, the situation is not as tragic as it first appears. More than a thousand new species have been discovered or renamed and only 18 percent are freshwater planktonic species, which garner the most interest in routine analyses. Most new taxa are described from terrestrial habitats. Despite the increase in studies from tropical areas, most of the new species are from the temperate zone, which probably does not account for the reality. Significant advances in modern taxonomy are visible mainly for the trichal types, but other groups such as the pleurocapsal species are considerably less studied. In this article I try to show that, despite all the difficulties and limitations, it is not necessary to consider these rapid changes as a complication in common cyanobacteriological research. [ABSTRACT FROM AUTHOR]

A unicellular cyanobacterium, strain VI4D9, was isolated from thermophilic microbial mats thriving in a hot spring of the Ahousaht territory of Vancouver Island, Canada, and characterized using optical and electron microscopy, genome sequencing and cultivation approaches. The cells were elongated rods (5.1 µm in length and 1.2 µm in width, on average). Their UV visible absorption spectra revealed that they contain chlorophyll a, phycocyanin and carotenoids. Transmission electron microscopy showed the presence of thylakoids concentrated on one side of the cells. The strain grew within a temperature range of 37–50°C, with an optimum growth at 45°C. Its genome had a size of 3 049 282 bp and a DNA G + C content of 51.8 mol%. The cells contained numerous intracellular spherical granules easily visible under scanning electron microscopy. Energy dispersive X-ray spectroscopy revealed that these granules were made of Ca-, Ba- and Sr-containing carbonates. A phylogenetic 16S rRNA gene tree robustly placed this strain as sister to several environmental sequences and the described species Gloeomargarita lithophora, also characterized by the possession of intracellular carbonate inclusions. We consider strain VI4D9 to represent a new Gloeomargarita species based on its marked phenotypic differences with G. lithophora, notably, its thermophilic nature and different thylakoid organization, therefore we propose the name Gloeomargarita ahousahtiae sp. nov. The type strain is VI4D9 (Culture Collection of Algae and Protozoa strain 1472/1; Laboratorio de Algas Continentales Mexico strain LAC 140). Gloeomargarita ahousahtiae is the second species described within the recently discovered order Gloeomargaritales. Gloeomargarita ahousahtiae is a new thermophilic cyanobacterium. Growth temperature and thylakoid morphology differentiate G. ahousahtiae and G. lithophora. All described Gloeomargaritales synthesize intracellular carbonate inclusions. [ABSTRACT FROM AUTHOR]

The effects of different ferrous sulfate (FeSO4) concentrations on the fatty acid profile of the blue-green alga Arthrospira platensis cultured in Zarrouk's medium to produce biodiesel were studied. Different ferrous sulfate concentrations (0, 0.005, 0.01, 0.05, and 0.1 g/L) and 0.01 g/L were examined on the biochemical composition of the alga and fatty acids profile of A. platensis. Findings revealed that the highest and lowest yields of fatty acid were 0 and 0.1 g/L FeSO4, respectively. It was also noticed an increase of palmitic acid, oleic acid, linoleic acid, γ-linolenic acid, and docosahexaenoic acid when ferrous sulfate was between 0.05 and 0.1 g/L, while these fatty acids decreased at low concentration. Ferrous sulfate at a concentration of 0.1 g/L exhibited an increase and best yields in the following: growth rate and the shortest doubling time, chlorophyll-a, phycocyanin, allophycocyanin, phycobiliproteins, and carotenoids. Thus, increasing the FeSO4 concentration to 0.1 g/L has led to the increase in fatty acid individuals, which in turn, resulted in potential enhancement of the biodiesel production from A. platensis. [ABSTRACT FROM AUTHOR]

The blue-green algae are known as Anabaena flos-aquae, which is a nutrient-rich food supply. The 2nd and 4th larval instars of the cotton bollworm, Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) were tested in a lab using a crude extract of the cyanobacterial isolates of the Anabaena flos-aquae alga. The algal extract was administered to larvae via contact and feeding techniques. Depending on the larval instars and the applying technique, the algal extract's effects changed. Contact algal treatment was more successful than the feeding treatment. Also, the second larval instar was more vulnerable than the fourth. In terms of contact treatment, the LC50 value for the second larval instar was 0.0125 ml/l, while the fourth instar's 0.025 ml/l. In terms of feeding treatment, the LC50 value was 0.05 and 0.1 ml/l for the second and fourth instars, respectively. In contrast to controls, where adults emerged at a rate of 100% compared to 85%- 86% adults emerged as second instar and fourth instar in terms of feeding method, respectively. While adults emerged of second instar and fourth instar in terms of contact method was 81%-93%, respectively. The contact method's LC50 value for the second larval instar caused a highly significant increase in larval and pupal durations and a drop in adult emergence. Also, the contact method's LC50 value for the second larval instar caused the greatest percentage of pupation malformation 37%, and adult malformation (19%). Also, adults that emerged from the contact-treated 4th larval instar showed a significant decrease in egg hatchability to 82.4%. It was found that the proportion of pupation had significantly decreased. Additionally, adult longevity and adult emergence percentage were decreased for contact or feeding treatments on the fourth larval instar. [ABSTRACT FROM AUTHOR]

Cyanobacteria blooms represent a global problem with human health and economic and ecosystem nuisance effects. Until now, we have used arbitrary and sometimes confusing criteria to decide whether we are in the presence of a Cyanobacteria bloom. Through scientometric analysis of studies published between 1953 and 2022, I aimed to identify a threshold value that can be used to quantify Cyanobacteria blooms numerically. I considered several methodological approaches (field, field-experimental, and satellite data) and kinds of environments (coastal, marine, and continental ecosystems). The analysis revealed that 48% of the papers used "cyanobacteria bloom" or similar terms qualitatively without providing or employing a quantitative definition. These papers were focused on other topics related to the ecology of Cyanobacteria (78%), while some others (21%) defined blooms by using visual criteria (scum visualization or water discoloration). Of the other half (52%), a few were mathematical models or review papers (5%), while the rest (65%) defined blooms quantitatively. Of these, most reports (approximately 80%) were from eutrophic inland waters and reported mean values for blooms between 80 000 and 249 000 cells mL−1 or 41 and 69 µg L−1 of chlorophyll-a. Calculations were also carried out for oligotrophic to mesotrophic inland waters and marine-coastal waters, which had fewer reports available in the literature. This is a first attempt to identify a consensual definition based on values reported as blooms in nature, a threshold that can undoubtedly be useful in the future to make possible comparisons among several environments and temporal scales. [ABSTRACT FROM AUTHOR]

In order to assess the impact of cyanobacteria on mollusks under experimental conditions, the interaction of toxic and nontoxic strains of the cyanobacterium Microcystis aeruginosa (Kützing) Kützing and bivalve mollusks Unio pictorum (Linnaeus, 1758) has been studied. Cyanobacteria have a negative effect on bivalve mollusks: the 40% death of mollusks and deterioration of their adaptive capacity are recorded when cocultivated with M. aeruginosa at a high cell concentration. At the same time, there is no difference in the mortality of mollusks incubated with toxic and nontoxic cyanobacteria. A decrease in the content of microcystin-LR in the presence of bivalves is revealed. No statistically significant increase in the number of cyanobacteria in the water is noted after transit passage through the digestive system of bivalves. [ABSTRACT FROM AUTHOR]

Abstract Harmful algal blooms (HABs) formed by freshwater cyanobacteria pose risks to human and ecological health globally. Some cyanobacteria form overwintering cells that remain in the sediment during non‐ideal growth conditions and provide an inoculum for HABs during the growing season, perpetuating the cyanobacterial life cycle. Preventative management targeted at decreasing the viability of overwintering cells is an attractive strategy for limiting HAB formation and decreasing risks. However, this approach is novel, and information is needed for sampling, identification and enumeration of overwintering cells in sediments as well as methods for determining if overwintering cells have the potential to contribute to HAB formation. Peer reviewed literature related to these topics are available; yet these data need to be synthesized and placed into the context of management. Therefore, a strategic review was conducted to inform methods and data needs for this preventative strategy. To sample overwintering cells, corers or dredges are used to collect surficial (0–2 cm) sediment layers containing overwintering cells. Identification and enumeration of overwintering cells via light microscopy are aided by dilution, sieving, or density separation of cells from sediment. Incubation studies which simulate environmental conditions triggering akinete germination and cell growth provide evidence of overwintering cell viability. Critical environmental conditions are light (≥0.5 μmol m−2 s−1) and temperature (20–30°C) for triggering akinete germination and growth of quiescent vegetative Microcystis sp. cells, respectively. Limited information was available on the roles of mixing and dissolved oxygen as environmental conditions for germination and growth. Synthesized information can be used to identify potential areas of concern in which overwintering cells are contributing to HABs. Additionally, this information can be used to design incubation studies in which field collected sediments containing overwintering cells are placed in ideal environmental conditions for germination and growth and cyanobacteria transferring to the water column are measured over time. These data inform investigations of areas that are candidates for preventative management and measurements of overwintering cell responses to management.

Commercially produced cyanobacteria preparations sold under the name spirulina are widely consumed, due to their traditional use as a nutrient-rich foodstuff and subsequent marketing as a superfood. Despite their popularity, the microbial composition of ponds used to cultivate these bacteria is understudied. A total of 19 pond samples were obtained from small-scale spirulina farms and subjected to metagenome and/or virome sequencing, and the results were analysed. A remarkable level of prokaryotic and viral diversity was found to be present in the ponds, with Limnospira sp. and Arthrospira sp. sometimes being notably scarce. A detailed breakdown of prokaryotic and viral components of 15 samples is presented. Twenty putative Limnospira sp.-infecting bacteriophage contigs were identified, though no correlation between the performance of these cultures and the presence of phages was found. The high diversity of these samples prevented the identification of clear trends in sample performance over time, between ponds or when comparing successful and failed fermentations.

A multifunctional weir was built on the Nakdong River. As a result, changes in the river environment occurred, such as an increase in river residence time. This causes changes in water quality, including green algae. The occurrence of green algae in the Nakdong River, which is used as a water source, also affects the purified water supply system. In particular, the mass spread of harmful algae is becoming a major problem as the frequency and intensity of occurrences increase. There are various causes of blue-green algae. We would like to examine the relationships between causal factors through a decision tree-based algorithm. Additionally, we would like to predict the occurrence of green algae based on the combination of these factors. For prediction, we studied categorical prediction based on the blue-green algae warning system used in Korea. RF, Catboost and XGBoost algorithms were used. Optimal hyperparameters were applied. We compared the prediction performance of each algorithm. In addition, the predictability of using sensor-based data was reviewed for a preemptive response to the occurrence of blue-green algae. By applying sensor-based data, the accuracy was over 80%. Prediction accuracy by category was also over 75%. It is believed that real-time prediction is possible through sensor-based factors. The optimal forecast period was analyzed to determine whether a preemptive response was possible and the possibility of improvement was examined through the segmentation of prediction categories. When there were three categories, 79% of predictions were possible by the 21st day. In seven categories, 75% prediction was possible up to 14 days. In this study, sensor-based categorical predictability was derived. In addition, real-time response and proactive response were determined. Such sensor-based algae prediction research is considered important for future blue-green algae management and river management. [ABSTRACT FROM AUTHOR]

In 2019, cyanobacterial samples were collected from thermal sites in Yellowstone National Park. In this paper, we discuss the considerable richness of representatives of simple filamentous cyanobacteria. Using a polyphasic approach, one new genus, Copelandiella, with two species (C. yellowstonensis and C. thermalis) and eight additional new species Albertania prattii, K. anagnostidisii, Kovacikia brockii, Leptolyngbya tildenae, L. vaporiphila, Nodosilinea calida, N. igneolacustris, and Oculatella castenholzii were described. At the same time, by analyzing our new molecular data, we concluded that other genera of trichal cyanobacteria can be merged with existing genera: species within the genus Plectolyngbya are herein transferred to Leptolyngbya, and if some nomenclatural issues are resolved, species within the genus Leptothermofonsia will be subsequently transferred to the genus Kovacikia, an earlier synonym. [ABSTRACT FROM AUTHOR]

Climate and anthropogenic change, particularly agricultural runoff, increase blue-green algae/cyanobacteria blooms. This article researches cyanobacteria alert-level identification, management, and risk communication in Lake Hume, Australia. Two methods, document and content analysis, evidence contamination events and risk communication, reflect water governance and data management limitations. Results found that Lake Hume had amber or red alerts for only one week, December 2021–December 2022. This failed to prevent government tourism promotion of recreational usage, contravening water authority red alert advice. Lake-use restrictions lacked compliance enforcement. Events during amber alerts lacked risk communication to vulnerable populations (children). Lake Hume's governance by the Murray–Darling Basin Authority restricted risk communication to one authority that reproduced generic advice in minimal outlets/time points. Geophysical signage failed to address diversity needs (language, literacy, age, and disabilities). No risk communication was found for residents with diseases exacerbated by aerosolization. Despite WHO promoting cyanotoxin investigation, Australian research is absent in international literature. Further, Lake Hume cyanobacteria produce potentially carcinogenic microcystein. This coexists with census data revealing cancer rates higher than the national average in a waterside town. The results demonstrate the need to incorporate robust public health risk assessments, communication, and management into water management and advocate international legislation changes based on evidence-based research to reduce blooms and prevent agricultural runoff. [ABSTRACT FROM AUTHOR]

A redefinition of the cyanobacterial lineage has been proposed based on phylogenomic analysis of distantly related nonphototrophic lineages. We define Cyanobacteria here as "Organisms in the domain bacteria able to carry out oxygenic photosynthesis with water as an electron donor and to reduce carbon dioxide as a source of carbon, or those secondarily evolved from such organisms."

Objectives The purpose of this study is to provide basic data for the development of a rapid and easy to measure alternative indicator for estimating the number of cyanobacteria cells in the field.Methods:Phycocyanin, algal cell number, and water quality items were measured at the left, middle, and right points of Maery Bridge near the Mulgeum and Maery algae monitoring network located downstream of the Nakdong River. The phycocyanin concentration(PC) was measured in the field using the LISST-HAB sensor, which is a fluorescence concentration analyzer, and comparative analysis was performed with the number of algal cells by algae species. Results and Discussion As a limiting factor for blue-green algae occurrence, the correlation coefficient (r) between T-P and Blue-green algae (BGA) was 0.58 (≥0.3). Phycocyanin and Blue-green algae showed a high significant correlation at 0.96 (≥0.3). Prob (F-statistics) of the blue-green algae cell count estimation formula using phycocyanin was less than 0.05, showing a significant result. The estimation formula was estimated BGA(cells/mL) = 326.95×PC+50,484. As a result of the analysis of the predicted and measured values of Blue-green algae, r2 was 0.988, indicating a high coefficient of determination and 92.5% accuracy. Conclusion The correlation analysis with the number of cyanobacteria showed a high significant correlation with phycocyanin of 0.96 (≥0.3), followed by T-P, a limiting factor for the occurrence of cyanobacteria, of 0.58 (≥0.3) indicating a significant correlation. In addition, the formula for estimating the number of blue-green algae cells using phycocyanin was found to be BGA (cells/mL)=326.95×PC+50,484 in which r2 was 0.927, and Prob (F-statistics) was less than 0.05. As a result of analyzing the predicted and measured values ​​of cyanobacteria cell numbers, r2 was 0.988, indicating a high coefficient of determination, with accuracy of 92.5%. Through this results, it reveals that the number of cyanobacteria cells can be estimated using the sensor of the fluorescence concentration analyzer at the target point by substituting the phycocyanin concentration into the blue-green algae cell number estimation formula.

There is an urgent demand for biostimulant amendments that can sustainably alleviate osmotic stress. However, limited information is available about the integrated application of vermicompost and a cyanobacteria extract on cotton plants. In 2020 and 2021, two field experiments were carried out in which twelve combinations of three irrigation intervals were employed every 14 days (Irrig.14), 21 days (Irrig.21), and 28 days (Irrig.28) along with four amendment treatments (a control, vermicompost, cyanobacteria extract, and combination of vermicompost + cyanobacteria extract) in salt-affected soil. The integrative use of vermicompost and a cyanobacteria extract resulted in an observed improvement in the physicochemical attributes; non-enzymatic antioxidants (free amino acids, proline, total soluble sugars, and phenolics); and antioxidant enzyme activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) and a decrease in the levels of oxidative damage indicators (H2O2 and MDA). Significant augmentation in the content of chlorophyll a and b, carotenoid concentration, relative water content, stomatal conductance, and K+ was also observed. In conjunction with these findings, noticeable decreases in the content of Na+ and hydrogen peroxide (H2O2) and the degree of lipid peroxidation (MDA) proved the efficacy of this technique. Consequently, the highest cotton yield and productivity as well as fiber quality were achieved when vermicompost and a cyanobacteria extract were used together under increasing irrigation intervals in salt-affected soil. In conclusion, the integrated application of vermicompost and a cyanobacteria extract can be helpful for obtaining higher cotton productivity and fiber quality compared with the studied control and the individual applications of the vermicompost or the cyanobacteria extract under increasing irrigation intervals within salt-affected soil. Additionally, it can also help alleviate the harmful impact of these abiotic stresses. [ABSTRACT FROM AUTHOR]

Iron-modified biochar adsorbent shows its promise for removing Cr(VI) from water. However, the traditional dry-grinding modification methods to prepare iron-modified biochar (DFeBC) usually result in the aggregation of iron oxide particles, thus impeding the adsorption capacity. Herein, blue-green algae waste derived biochar modified in a wet process by K2FeO4 (WFeBC) was developed, and it showed well-distributed iron oxide on the surface of the biochar. As a result, WFeBC displayed a larger theoretical adsorption capacity of 66.22 mg/g than that of DFeBC (48.54 mg/g). It was found that the uniform-distributed iron oxide and abundant oxygen functional groups of WFeBC played an important role in the removal process of Cr(VI). In the adsorption process, the reduction of Cr(VI) to Cr(III) by Fe(II) promoted the removal of hexavalent chromium. The Cr(VI) will be attracted by protonated oxygen functional groups through electrostatic interaction and complexation in an acid environment. All the results show that the wet modification of biochar by K2FeO4 can effectively improve the removal ability of WFeBC to Cr(VI). [ABSTRACT FROM AUTHOR]

Water pollution is a major problem in India and most of the major rivers of the country are heavily polluted by different types of pollutants and invite the growth of various organisms including microalgae. The aim of the present investigation was to explore the biodiversity of the Blue-green algae from different polluted habitats of Meerut, Uttar Pradesh, India. The present paper deals with the diversity of non-heterocystous filamentous taxa of the family Pseudanabaenaceae. Water samples collected from three different polluted water reservoirs of Meerut, U.P., India were subjected to microscopic observations and identification. The present study revealed the occurrence of total 45 strains of 15 species and 8 genera belonging to three sub families including Pseudanabaenoideae, Spirulinoideae and Leptolyngbyoideae of the family Pseudanabaenaceae viz. Geitlerinema lemmermannii, G. nematode, Jaaginema gracile Leptolyngbya aspera, L. foveolarum, L. geysericola, L. gracilis, L. mycoidea; Limnothrix planctonica, Planktolyngbya contorta, Pseudanabaena limnetica, P. minima, P. Recta, Romeria mexicana and Spirulina subsalsa. The study also revealed the unexplored diversity of non-heterocystous filamentous blue green algae from three polluted water reservoirs of Meerut, U.P., India. [ABSTRACT FROM AUTHOR]

Increases in algal growth have been reported in rivers, reservoirs, and other water resources worldwide, including Korea. Algal overgrowth can result in algal bloom, which has several negative impacts, such as ecosystem degradation and economic losses. Mitigation measures employed in Korea include an algal warning system and survey-based water quality forecast systems. However, these methods are time-consuming and require sample collection from the site. On the other hand, remote sensing techniques that use chlorophyll a are unable to distinguish between different types of algal species. In this paper, we aimed to identify a classification technique based on remote sensing methods that can be used to distinguish between blue-green algae and green algae. We acquired and prepared an algal culture solution and used a hyperspectral sensor to obtain an algae spectrum. Thereafter, we measured the absorption and emission spectra of blue-green and green algae and distinguished them using the instantaneous slope change of the spectrum. The absorption spectra for green algae showed two peaks at 417–437 nm and 661–673 nm, whereas those of blue-green algae showed three peaks at 449–529 nm, 433–437 nm, and 669–677 nm. The results of this study could form a basis for developing mitigation measures for algal overgrowth. [ABSTRACT FROM AUTHOR]

Harmful cyanobacterial blooms plague reservoirs and lakes used for a variety of purposes, such as recreation and drinking water. Chemical controls are frequently used to mitigate the occurrence of cyanobacterial blooms given that many are fast-acting and effective at reducing cyanobacterial abundance. Recent research has identified hydrogen peroxide (H2O2) as an environmentally friendly alternative to algaecides that have typically been used, such as copper sulfate. To build on past studies, these experiments sought to further understand how well H2O2 treatments reduce cyanobacteria in complex eutrophic conditions, as well as to assess treatment effects on a non-target phytoplankter, a green alga. We assessed the effectiveness of H2O2 (at treatments of 2–16 mg L−1) under varying environmental conditions in a controlled laboratory setting, including (1) dissolved organic matter (DOM) concentrations (humic acid; 0–60 mg L−1), (2) temperature (20, 25, and 32 °C), and (3) initial algal biomass (chlorophyll-a; 82–371 µg L−1). In contrast to our expectations, neither DOM concentration nor temperature meaningfully impacted the effectiveness of H2O2 at reducing cyanobacteria. However, initial algal biomass as well as H2O2 treatment dose greatly influenced the effectiveness of the algaecide on cyanobacteria. Treatments of ≥ 8 mg H2O2 L−1 on algal biomass were significantly buffered with higher DOM and lower temperature, and the biological significance of these findings should be explored further. Across all experiments, H2O2 concentrations of 0.03–0.12 mg H2O2 L−1 µg chlorophyll L−1 were effective at significantly reducing cyanobacteria with varying effects on algal biomass. Thus, water resource managers are encouraged to consider how ambient levels of phytoplankton biomass may affect the ability of H2O2 to control cyanobacterial blooms prior to treatment. [ABSTRACT FROM AUTHOR]

Several changes have occurred in the river environment of Nakdong river due to the construction of multifunctional weirs as part of the Four Major Rivers Project. This river currently exhibits characteristics that are similar to those of a stagnant water area in which the river depth increases and the flow velocity decreases. Consequently, blue-green algae are frequently observed. Toxic substances secreted by blue-green algae are harmful to aquatic ecosystems and the human body; therefore, ensuring the stability of the water quality of Nakdong river is of utmost importance. Various factors are associated with the occurrence of blue-green algae. Therefore, the causal relationship between these causative factors must be identified. In this study, we investigated factors influencing algal growth, such as water quality, hydraulics, and weather, and algal occurrence patterns by site were analyzed. Recent studies have used data mining and machine-learning techniques in algal management to quantitatively identify the characteristics of blue-green algae. In machine learning, the prediction results differ depending on the selection of parameters, which are an important aspect in the management of blue-green algae with complex causes. In this study, we quantitatively analyzed the conditions for the occurrence of cyanobacteria according to the influencing factors using decision trees and random forests, which are machine-learning techniques, along with an analysis of the major complex factors influencing the occurrence of blue-green algae in the Nakdong river weirs. Considering the water quality and hydraulic factors, we analyzed the characteristics of algal generation in each weir at different hydraulic volume times. In addition, we investigated the possibility of improving the accuracy of cyanobacterial prediction according to the learning factors. Through these analyses, we attempted to study the characteristics of blue-green algae in stagnant rivers. [ABSTRACT FROM AUTHOR]

This study has investigated the key contribution of sodium acetate as co-substrate on the performances of microbial fuel cells (MFC) during the conversion of a toxic blue-green algae (BGA) biomass into bioelectricity. Microcystis aeruginosa biomass was employed as a target substrate and sodium acetate (AC) as a co-substrate. Compared with MFC treated with BGA alone (MFC-BGA), the MFCs treated with BGA together with acetate (MFC-BGA-AC) significantly magnified the voltage output by 261.3%. Moreover, the addition of co-substrate extended the electric batch cycle by 253.1% and 7.9% compared with MFC-BGA-AC and its corresponding MFC treated only with AC (MFC-AC), respectively. The co-substrate strategy also enhanced the maximum power density by a factor of 3.53 MFC-BGA and 1.2 MFC-AC. It has also displayed the smallest charge transfer resistance of 12.01 Ω which was approximately 45.8% lower than that of MFC-BGA and even slightly lower than the control. Based on the transmission electron microscope results, the cell morphology was also less affected in MFC-BGA-AC. Thus, our new study revealed that the co-substrate could empower the bio-electrochemical active bacteria for toxin survival and make a crucial contribution in alleviating the internal resistance within the operating reactors, which consequently promote the transfer of the generated charges to the bio-anode for power production evolution. The current investigation will conspicuously help in paving ways toward sustainable clean energy production and durable wastes control in the aquatic environment. [ABSTRACT FROM AUTHOR]

Favot EJ, Holeton C, DeSellas AM, Paterson AM. 2023. Cyanobacterial blooms in Ontario, Canada: continued increase in reports through the 21st century. Lake Reserv Manage. 39:1–20. The Ontario Ministry of the Environment, Conservation and Parks samples algal composition in response to public reports of suspected algal blooms, which have been tracked since 1994. In a previous analysis, Winter et al. noted a significant increase in the number of reports of confirmed algal blooms dominated by cyanobacteria from 1994 to 2009. Here, we determined that this increasing trend in the yearly number of confirmed cyanobacterial bloom reports (CCBRs) has persisted in Ontario over the intervening decade, to 2019. More than half of CCBRs were from waterbodies on the Precambrian Shield, in the Georgian Bay (5E) ecoregion, known for cottaging and water-based tourism. Data from the Ontario Lake Partner Program (LPP) was used to investigate total phosphorus (TP) concentrations in waterbodies with CCBRs. Approximately 44% of the waterbodies with a CCBR (mean TP 12.99 µg/L, n = 135) had average spring TP concentrations less than 10 µg/L, compared to 64% for LPP waterbodies with no reported or confirmed cyanobacterial blooms (mean TP 9.79 µg/L, n = 918). The most common taxon of cyanobacteria dominating bloom samples in inland waterbodies was Dolichospermum, followed by Aphanizomenon in waterbodies on the Precambrian Shield, and Microcystis in the Mixedwood Plains ecozone in southern Ontario. While an increase in public awareness cannot be ruled out in contributing to the rise in CCBRs across Ontario, the high proportion of cyanobacterial blooms occurring in oligotrophic waterbodies suggests that there may be a link to climate warming, rendering conditions more favorable for these blooms to occur. [ABSTRACT FROM AUTHOR]

Beal MRW, O'Reilly BE, Soley CK, Hietpas KR, Block PJ. 2022. Variability of summer cyanobacteria abundance: can season-ahead forecasts improve beach management? Lake Reserv Manage. 39:37–52. As anthropogenic eutrophication and the associated increase of cyanobacteria continue to plague inland waterbodies, local officials are seeking novel methods to proactively manage water resources. Cyanobacteria are of particular concern to health officials due to their ability to produce dangerous hepatotoxins and neurotoxins, which can threaten waterbodies for recreational and drinking-water purposes. Presently, however, there is no cyanobacteria outlook that can provide advance warning of a potential threat at the seasonal time scale. In this study, a statistical model is developed utilizing local and global scale season-ahead hydroclimatic predictors to evaluate the potential for informative cyanobacteria biomass and associated beach closure forecasts across the June–August season for a eutrophic lake in Wisconsin (United States). This model is developed as part of a subseasonal to seasonal cyanobacteria forecasting system to optimize lake management across the peak cyanobacteria season. Model skill is significant in comparison to June–August cyanobacteria observations (Pearson correlation coefficient = 0.62, Heidke skill score = 0.38). The modeling framework proposed here demonstrates encouraging prediction skill and offers the possibility of advanced beach management applications. [ABSTRACT FROM AUTHOR]

Cyanobacteria or blue algae are ubiquitously present in both fresh and brackish water environments. They also grow in conditions of high humidity, colonizing stones or monuments and fountain surfaces, and creating thick biofilms able to induce biodeterioration in the constituent materials of artefacts. As well as several photoautotrophic organisms, cyanobacteria belong to the microorganisms identified as primary colonizers, playing an important role in stone artwork deterioration. In this study, an analysis was made of the biofilm collected from the stone fountain of the Two Dragons in Palermo (Italy), revealing the presence of cyanobacterial colonies by optical microscopy, due to their peculiar auto-fluorescence. Furthermore, molecular investigations by qPCR (quantitative Polymerase Chain Reaction) were utilized to gather quantitative information, and phylogenetics analysis was used to confirm the Thioredox- in reductase (TrxR) gene as a suitable molecular marker. The results highlight the presence of cyanobacteria as the main taxa, whose growth is induced by microclimatic and environmental conditions, and by the physical characteristics of the stone surface. Identification of microbial populations living on stone artworks is the starting point for successful control and conservation strategies, which can help to define the correct protocols to block cellular activity and to find appropriate methods for removing biofilm, as well as counteracting possible recolonization.

Beta-N-methylamino-L-alanine, or BMAA, produced by cyanobacteria, can be considered neurotoxic at concentrations of 10-30 mn. Increases in cyanobacteria (blue-green algae) blooms often result in elevated BMAA in the environment. While earlier experiments show neurotoxic effects of BMAA oil developing fish emblyos. there are limited data on the enduring effects in adult fish. FGCU pilot studles of BMAA effects on adult zebrafish suggest negative impacts on brain tissue and swimming behavior. Given the observed effects on locomotion, our goal was to determine possible effects of BMAA on motor neurons located in the spinal cord. In order to test the hypothesis that cell death and degeneration of motor neurons increased as BMAA concentration increased. adult zebrafish were exposed to zero, low, medium, and high concentrations of BMAA, based on local concentrations reported for Sarasota Bay. Dissected spinal cords of exposed fish were used with an immunohistochemical marker for the apoptotic protein caspase and fluorescence microscopy to evaluate cell death and motor neuron density. The quantitative image analysis results presented here will help us further understand the relationship between BMAA and neurodegeneration. Ultimately, studies using zebrafish to model effects of environmental neurotoxins would yield important implications to both wildlife and human health. [ABSTRACT FROM AUTHOR]

In recent years, the consumption of blue-green algae (BGA) dietary supplements is increasing because of their health benefits. However, cyanobacteria can produce cyanotoxins, which present serious health risks. In this work we propose hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry (HILIC-MS/MS) to determine cyanotoxins in BGA dietary supplements. Target toxins, including microcystin-leucine-arginine (MC-LR) and microcystin-arginine-arginine (MC-RR), nodularin, anatoxin-a and three non-protein amino acids, β-N-methylamino-L-alanine (BMAA), 2,4-diaminobutyric acid (DAB) and N-(2-aminoethyl)glycine (AEG), were separated using a SeQuant ZIC-HILIC column. Cyanotoxin extraction was based on solid–liquid extraction (SLE) followed by a tandem-solid phase extraction (SPE) procedure using Strata-X and mixed-mode cation-exchange (MCX) cartridges. The method was validated for BGA dietary supplements obtaining quantification limits from 60 to 300 µg·kg−1. Nine different commercial supplements were analyzed, and DAB, AEG, and MCs were found in some samples, highlighting the relevance of monitoring these substances as precaution measures for the safe consumption of these products. [ABSTRACT FROM AUTHOR]

The demand for nanoparticles is increasing tremendously, and so is the risk of their foreseeable discharge into the environment. Nanoparticles contain a variety of features, including anti-microbial properties, and have been shown to have toxic effects on aquatic organisms previously. However, the causes of nanoparticle toxicity under environmental conditions are still unknown. Exposure to nanoparticles in the environment is unavoidable as nanomaterials are used more prevalent in our daily lives, and as a result, nanotoxicity research is gaining traction. To understand the impact of nanoparticle toxicity on aquatic biota, cyanobacteria (blue-green algae) are an ideal model system. The cyanobacteria play an important role in ecological balance, nutrient cycling, energy flow, biological nitrogen fixation, and environmental remediation, and their susceptibility to nanoparticles can help in making a wise strategy for the mitigation of possible nano-pollution. This article presents an analysis of recent research findings on the toxicological influences of nanoparticles on the growth rate, biochemical changes, ultra-structural changes as well as the nanoparticle toxicity mechanisms in cyanobacteria. The finding suggests that the shading effect, generation of reactive oxygen species, membrane damage and disintegration of pigments are the main reasons for nanoparticle toxicity to the cyanobacteria. [ABSTRACT FROM AUTHOR]

The blue-green algal (BGA) bloom that appeared in Padmatheertham, the sacred pond in Sree Padmanabha Swamy Temple, Thiruvananthapuram, Kerala, India is associated with Spirulina platensis, a cyanobacterium rich in proteins, considered as a safe, functional food. Considering the unaesthetic appearance of the BGA bloom and its foul odour on open decomposition, various non-chemical methods were employed for its control. Several methods for nutrient remediation in the pond system were also explored. The efficacy of using decomposing rice straw to inhibit algal growth was studied. The possibility of control of BGA by stocking tilapia and filter-feeding bivalve, Villorita cyprinoides capable of ingesting and digesting the algae was analysed. Experimental assays carried out on V. cyprinoides revealed that it helped in the rapid utilization of BGA. The present study reinforces our understanding of the fundamental ecosystem services that filter-feeder communities provide to counter the invasive effects of eutrophication through consumption and assimilation. [ABSTRACT FROM AUTHOR]

This study aims to identify the bioactive compounds contained in blue-green algae (Spirulina platensis), determine the malondialdehyde levels between groups induced by single dose X-ray radiotherapy (single fractionation of 10 Gy) and fractionation dose, and determine the ability of these active compounds to repair the lipid membrane damage of the fractionated dose irradiated group. Thirty-six male Rattus norvegicus were divided into six groups: K0 (control group), K1 (single dose irradiated group), K2 (fractionated dose irradiated group), P1 (group irradiated with fractionated dose and given 300 mg/kg BW blue-green algae), P2 (group irradiated at a fractionated dose and given 600 mg/kg BW blue-green algae), and P3 (group irradiated at a fractionated dose and given 900 mg/kg BW blue-green algae). The results showed that the group irradiated with a single dose showed a higher increase in malondialdehyde levels than the group induced by fractionated dose radiotherapy. The bioactive content of blue-green algae can reduce malondialdehyde levels. [ABSTRACT FROM AUTHOR]

An automatic algorithm is proposed for identifying areas of cyanobacteria (CB) blooms in the Azov Sea based on an analysis of the optical spectra of MODIS satellite data. The algorithm has been validated by comparison with high-resolution quasi-synchronous Landsat data. The results obtained with this algorithm were used to study the spatiotemporal variability of CB blooms in the Azov Sea in 2003–2019 and give examples of the evolution of blooms in individual years. CB blooms in the Azov Sea are observed from March to November with a peak in August. The most intense and longest CB blooms are observed in Taganrog Bay. In the spring months, they spread from here eastward along the northern coast. In June–July, CB begin to intensively spread southward along the eastern coast and then, in some years, they penetrate into the center of the basin under the action of anticyclonic currents. An analysis of interannual variability has shown that the intensity of blooms was the highest in 2004–2011, with a peak in 2008–2009, and dropped significantly in 2011–2019. One reason for this drop is the decreased flow of the Don and Kuban rivers, as well as the increased wind speed observed in recent years. [ABSTRACT FROM AUTHOR]

In order to explore the distribution of cyanobacteria in paddy soil under different ecological conditions, the composition, diversity, and environmental drivers of soil cyanobacteria communities in rice fields from six regions of Jilin Province (China) were investigated. The results showed that the 16S amplicon high-throughput sequence detected the existence of cyanobacteria of 16 phyla, 33 orders, 60 families, and 113 genera in the soil of rice fields in Jilin Province. The dominant cyanobacteria populations in Jilin Province paddy soils comprised Cyanobium_PCC-6307, Synechocystis_PCC-6803, Planktothrix_NIVA-CYA_15, and Nodosilinea_PCC-7104. Each soil sample included a significant proportion of nitrogen-fixing filamentous cyanobacteria Anabaena and Nostoc according to microscopic analysis. The structural properties and diversity of cyanobacteria communities differed by geography, with soil pH and SOC being the main environmental drivers of cyanobacteria community structure. The alkaline soils S1, S2, and S5 displayed greater diversity than the acidic soils S3, S4, and S6, with S5 displaying the greatest cyanobacteria diversity. This research has crucial implications for developing and utilizing local cyanobacteria resources. [ABSTRACT FROM AUTHOR]

A multifunctional weir was built on the Nakdong River. As a result, changes in the river environment occurred, such as an increase in river residence time. This causes changes in water quality, including green algae. The occurrence of green algae in the Nakdong River, which is used as a water source, also affects the purified water supply system. In particular, the mass spread of harmful algae is becoming a major problem as the frequency and intensity of occurrences increase. There are various causes of blue-green algae. We would like to examine the relationships between causal factors through a decision tree-based algorithm. Additionally, we would like to predict the occurrence of green algae based on the combination of these factors. For prediction, we studied categorical prediction based on the blue-green algae warning system used in Korea. RF, Catboost and XGBoost algorithms were used. Optimal hyperparameters were applied. We compared the prediction performance of each algorithm. In addition, the predictability of using sensor-based data was reviewed for a preemptive response to the occurrence of blue-green algae. By applying sensor-based data, the accuracy was over 80%. Prediction accuracy by category was also over 75%. It is believed that real-time prediction is possible through sensor-based factors. The optimal forecast period was analyzed to determine whether a preemptive response was possible and the possibility of improvement was examined through the segmentation of prediction categories. When there were three categories, 79% of predictions were possible by the 21st day. In seven categories, 75% prediction was possible up to 14 days. In this study, sensor-based categorical predictability was derived. In addition, real-time response and proactive response were determined. Such sensor-based algae prediction research is considered important for future blue-green algae management and river management.

Climate and anthropogenic change, particularly agricultural runoff, increase blue-green algae/cyanobacteria blooms. This article researches cyanobacteria alert-level identification, management, and risk communication in Lake Hume, Australia. Two methods, document and content analysis, evidence contamination events and risk communication, reflect water governance and data management limitations. Results found that Lake Hume had amber or red alerts for only one week, December 2021–December 2022. This failed to prevent government tourism promotion of recreational usage, contravening water authority red alert advice. Lake-use restrictions lacked compliance enforcement. Events during amber alerts lacked risk communication to vulnerable populations (children). Lake Hume’s governance by the Murray–Darling Basin Authority restricted risk communication to one authority that reproduced generic advice in minimal outlets/time points. Geophysical signage failed to address diversity needs (language, literacy, age, and disabilities). No risk communication was found for residents with diseases exacerbated by aerosolization. Despite WHO promoting cyanotoxin investigation, Australian research is absent in international literature. Further, Lake Hume cyanobacteria produce potentially carcinogenic microcystein. This coexists with census data revealing cancer rates higher than the national average in a waterside town. The results demonstrate the need to incorporate robust public health risk assessments, communication, and management into water management and advocate international legislation changes based on evidence-based research to reduce blooms and prevent agricultural runoff.

One of the bottlenecks in microalgae harvesting is the lack of an efficient method for separating the microalgae from its culture medium. Moreover, the lack of viable and simple preservation techniques for microalgae starters hinders the immediate recovery of cultures after experiencing collapse. Hence, the present study was conducted to evaluate the use of aluminium sulphate as a flocculant for harvesting spirulina (Arthrospira platensis) and compare it with other flocculation techniques (electrolytic flocculation and autoflocculation). Moreover, the use of antioxidants to lengthen the storage of viable spirulina cells in refrigerated conditions was explored. The results of the study showed that the optimum dosage of aluminium sulphate for flocculation of spirulina is 200 ppm with 94.82 ± 0.59% efficiency in 15 – 45 minutes post-administration. Moreover, the combination of ascorbic acid and alpha-tocopherol at 0.01% v/v resulted in the highest viable cells at 57.76 ± 2.48% until the 3-week refrigeration period. This may help in maintaining viable starters. However, further investigations are needed to ascertain residuals of aluminium in harvested biomass and explore low-cost options for its reduction or removal and optimize the use of antioxidants in spirulina preservation in refrigerated conditions.

Arthrospira species are widely cultivated due to their high nutritional value as a food supplement. The fluctuating temperature strongly influences the cultivation system for Arthrospira mass production. To reveal the underlying mechanisms of coping with temperature stress to adopt measures of harm reduction, we analyzed changes in growth, photosynthetic pigments and the transcriptome of Arthrospira sp. TJSD091 exposed to short-term cold stress. The photosynthetic pigments decreased significantly under cold temperature stress conditions, and so as the cells` dry weight. A total of 1294 genes were expressed differentially. Pathway analysis revealed 473 differentially expressed genes were identified in 32 KEGG pathways, of which 309 genes (65.33 %) are involved in the most affected metabolic pathway. The most sensitive metabolic pathways in response to cold stress involved energy metabolism, carbohydrate metabolism and photosynthesis proteins. The key hub regulatory genes were perceived as cyaA and genes related to two-component signal transduction systems. The genes regulated diverse metabolic functions to survive and grow. The increased respiration provided essential energy for basic motility maintenance under cold stress. The down-regulation of genes involved in photosynthesis, glycolysis, Calvin cycle and citrate cycle supported the low biomass production of the blue-green algae. The results provide a basis for revealing the survival mechanism of the blue-green algae to withstand cold stress at the gene transcription level.