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Radiocystis fernandoi: (A) general aspect of colony with mucilaginous envelope evidenced by China ink (from nature); (B) colony showing cells in radial alignment, arrow (from nature); (C) general aspect of colony (strain SPC 714, ASM-1 liquid medium); (D) detail of colony periphery showing cells in radial alignment, arrow (strain SPC 714, ASM-1 liquid medium). Scale Bar ¼ 20 mm.
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During the monitoring of toxic cyanobacteria in the Utinga Reservoir, which is the main drinking water supply for the city of Belém, PA, Brazil, a Radiocystis fernandoi strain (SPC714) was isolated. This non-axenic strain was submitted to a toxicity bioassay with mice and microcystin production analyzed by HPLC-DAD. The species was identified based...
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... colonies measuring 50-210 mm in diameter; cells are oval or spherical, with 5-7 mm in diameter, irregularly grouped in the colonial center and radiating in all directions to the periphery; cell content has highly visible aerotopes. The mucilaginous envelope varied from fine and colorless in culture material, to more evident in natural material (Fig. 1). The analyzed material can be misidentified as a Microcystis species, but R. fernandoi differs from Microcystis species by its radial arrangement of cells in the colony, as a result of the one-plane cell division. Sometimes R. fernandoi is misidentified as Microcystis botrys; and besides the differences discussed above, they strongly ...
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While evaluating several laboratory-cultured cyanobacteria strains for the presence of paralytic shellfish poison neurotoxins, the hydrophilic extract of Microcystis aeruginosa strain SPC777—isolated from Billings’s reservoir, São Paulo, Brazil—was found to exhibit lethal neurotoxic effect in mouse bioassay. The in vivo test showed symptoms that un...
Citations
... The new revision of the taxonomic system of cyanobacteria by Komárek et al. (2014) has already transferred the genus Radiocystis into the family Microcystaceae from Synechococcaceae, indicating the similarities between Radiocystis and Microcystis [8]. In particular, Radiocystis fernandoi is the most common species of the genus in tropical regions, and some strains of this species in Brazil have been shown to form heavy blooms and produce microcystins in freshwaters in different tropical and subtropical regions of the continent [37][38][39][40][41][42]. R. fernandoi has been reported to contribute more than 70% of the total cyanobacterial biomass in some blooms [38,[42][43][44]; therefore, this species is regarded as having great ecological importance in tropical regions. ...
Microcystis-dominated blooms cause environmental and ecological impacts worldwide. However, it is sometimes challenging to correctly identify Microcystis and its related genera. Radiocystis fernandoi Komárek et Komáková-Legnerová 1993, characterized by large cells and correspondingly large colonies with gas vesicles, has been frequently found in cyanobacterial blooms in Brazil. However, its molecular and phylogenetic identity is unknown because no valuable DNA sequences are available in GenBank. In this study, a strain with R. fernandoi morphology was successfully isolated from a cyanobacterial bloom sample in Lake Erhai, a subtropical plateau lake in China. Molecular characterization and phylogenetic analyses based on 16S rRNA and cpcBA genes revealed that the strain is different from the type species of the genus Radiocystis but formed a well-supported clade with the Microcystis species. The comparative results of the ITS region between 16S–23S rRNA genes also showed that the strain had very similar secondary structures to the species of Microcystis, supporting it as a new member of the genus Microcystis. Therefore, we propose the transfer of Radiocystis fernandoi into Microcystis fernandoi comb. nov. The correct identification and further taxonomic procedure for the bloom-forming cyanobacterial genera, such as Microcystis, Radiocystis, and Sphaerocavum, are also discussed in this study.
... There are still other toxins not common: aplysiatoxin, debromoaplysiatoxin and lyngbiatoxin-a, with distinct actions, such as dermatotoxic, tumor-promoting and gastric irritants, but not yet fully elucidated (Malik, et al., 2020). (Falconer et al., 1983;Rinehart et al., 1988;Turner et al. 1990;Lawton and Codd, 1991;Sivonen et al., 1991;Fawell et al., 1993;Yu, 1994;Yoshida et al., 1997;Jochimsen et al., 1998;Mahakhant et al., 1998;dos Vieira et al., 2003;Ballot, 2004;Botha et al., 2004;Ballot et al., 2005;Carey et al., 2007;Fiore et al., 2009;Chen et al., 2015;Spoof and Catherine, 2017). ...
Introduction: Cyanobacteria are organisms capable of producing a high number of bioactive molecules, known as cyanotoxins. Among the cyanotoxins, microcystins stand out, compounds with hepatotoxic potential. Studies claim that the most common and most toxic isoform among microcystins is microcystin-LR. One of the most frequently detected properties of microcystins is their ability to generate cellular oxidative stress. Thus, the present study is a bibliographic research about the biochemical mechanism of free radical generation caused by Microcystin LR. Methodology: for the preparation of this review, a survey was carried out in the national and international literature. The inclusion criteria for the construction of this work were original and review articles that addressed the ability of microcystin LR to generate oxidative damage. Results: Once they enter the body, microcystins accumulate in the liver, so that toxicity is associated with specific inhibition of protein phosphatase 1 and 2A (PP1 and PP2A), leading to disruption of cell integrity. Studies prove that MCs produce oxidative stress in vitro and in vivo and that they can act as tumor promoters. Conclusion: there is a possible relationship between cellular oxidative stress caused by microcystin. Thus, cyanobacterial blooms represent a threat to the health of several animals, including man, however, further studies on the topic addressed are needed.
... However, in addition to the aforementioned genera, sequences classified to the following were also included in this analysis. Radiocystis has been shown to have identical 16S rRNA genes as Microcystis (Vidal et al., 2021) and toxicity (Vieira et al., 2003). Cyanobium is another potentially toxic picocyanobacterial genera (Śliwińska-Wilczewska et al., 2018) detected in high relative abundances in these samples. ...
... Sequences classified to two additional genera were also included herein. Radiocystis can carry 16S rRNA genes that are identical Microcystis (Vidal et al., 2014) and can produce toxin (Vieira et al., 2003). Cyanobium is a potentially toxic picocyanobacteria that is increasingly implicated as a contributor to phytoplankton blooms (Śliwińska-Wilczewska et al., 2018). ...
Cyanobacteria, a group of photosynthetic bacteria, threaten water quality and drinking water resources globally through the production of potent toxins and the formation of dense surface blooms. These bloom events are increasing in intensity, frequency, and duration due to warming climates and anthropogenic land use and require monitoring programs for water quality management. However, cyanobacteria vary both spatially and temporally and if sampling efforts do not reflect this variation, potentially toxic organisms may be undetected or underestimated. This thesis explores the spatiotemporal trends of cyanobacterial communities in a series of interconnected, oligotrophic lakes in a northern temperate watershed (Turkey Lakes Watershed; North Part, ON) using next-generation sequencing (NGS). Next-generation sequencing of marker genes allows for rapid characterization of environmental communities and has become increasingly accessible, allowing for interdisciplinary applications. Optimal approaches in data handling and analysis are debated due to key challenges arising due to the data structure. Amplicon sequencing samples will vary in library sizes—the total number of reads—but this variation is not biologically meaningful and library sizes must be normalized to account for these differences. Rarefying, the process of subsampling to a normalized size, is frequently used to account for this variation but has been highly criticized due to the omission of valid data. To address the concerns of data omission, repeated iterations of rarefying were evaluated as a normalization technique in diversity analyses (Chapter 2). Repeatedly rarefying was demonstrated to characterize variation introduced through subsampling for applications in diversity analyses. This technique was implemented in the subsequent analysis of cyanobacterial communities in this thesis. Cyanobacterial communities are dynamic exhibiting heterogeneity in their spatial and temporal distribution in lakes. This spatiotemporal variation is driven by environmental conditions and physical characteristics (e.g., cell size, cell density) of taxa and can subsequently create challenges in monitoring. The spatiotemporal variation of cyanobacterial communities was characterized on both a diurnal scale (Chapter 3) and seasonal scale (Chapter 4) through amplicon sequencing of the V4 region of the 16S rRNA gene. Although the lakes in this study did not have visible bloom biomass, cyanobacterial sequences comprised up to 56% of the bacterial community and were frequently dominated by sequences classified as picocyanobacterial genera, which range from 0.2 – 2.0 µm in diameter. This dominance exemplifies the inability to rely on visual detection as a monitoring technique. In both studies, trends in the spatiotemporal variation varied between the lake sites due to differences in morphometry, thermal stratification and surrounding landscape processes demonstrating the impact of system specific characteristics on cyanobacterial dynamics. In combination with warming climates in temperate zones, cyanobacterial growth habits may change and appear as significant components of the bacterial community as early as May in oligotrophic lakes contrasting the previous perception of peak occurrence in the late summer requiring monitoring protocols to re-evaluate appropriate sampling time frames in temperate systems. The research conducted in this thesis identifies key areas for developing ecologically relevant sampling guidelines for cyanobacterial monitoring in lakes. Monitoring protocols are frequently developed from characteristics of common bloom forming taxa resulting in reliance on visual observation of biomass at the surface of the water and focusing sampling efforts to the summer months when blooms typically occur. This research demonstrated the flaws in these assumptions and provides a discussion on appropriate recommendations. Specifically, cyanobacterial community dynamics were demonstrated to be impacted by system specific characteristics and sampling protocols must be tailored to reflect the (i) physicochemical characteristics of the system, and (ii) ecological community structure. The research presented herein demonstrates the need for re-evaluation of current guidelines due to shifts in cyanobacterial growth habits in response to warming climates, and the reported dominance of picocyanobacteria which may impose toxicity risks despite the absence of visible biomass
... Each of the cultures exposed to the different lactones was observed under an optical microscope to identify growth and morphology, specifically the mucilage formation using acid staining with Chinese ink [12]. ...
Although several theories have been postulated to explain cyanobacterial blooms, their biochemical origin has not yet been found. In this work, we explore the existence of bacterial communication, called quorum sensing, in Microcystis aeruginosa and Cylindrospermopsis raciborskii. Thus, the application of several known acylhomoserine lactones to cultures of both cyanobacteria causes profound metabolic. At 72 h post-application, some of them produced substantial increases in cell proliferation, while others were inhibitors. There was a correlation with colony-forming activity for most of them. According to ELISA analysis, the microcystin levels were increased with some lactones. However, there was a clear difference between M. aeruginosa and C. raciborskii culture since, in the first one, there was an inducing effect on cell proliferation, while in C. raciborskii, the effects were minor. Besides, there were compound inhibitors and inducers of microcystins production in M. aeruginosa, but almost all compounds were only inducers of saxitoxin production in C. raciborskii. Moreover, each lactone appears to be involved in a specific quorum sensing process. From these results, the formation of cyanobacterial blooms in dams and reservoirs could be explained since lactones may come from cyanobacteria and other sources as bacterial microflora-associated or exogenous compounds structurally unrelated to lactones, such as drugs, industrial effluents, and agrochemicals.
... At Burrendong Dam, which was dominated by the microcystin-producing genera Microcystis aeuginosa and Radiocystis sp. (Vieira et al. 2003;Rastogi et al. 2015), the micronutrient treatment (M) had a slightly higher proportion of cyanobacteria than the control, and the NPM treatment had a higher proportion of cyanobacteria than the NP treatment. This indicates that cyanobacteria may be more successful competitors in the phytoplankton community with higher micronutrient concentrations. ...
The role of trace metal micronutrients in limiting cyanobacterial growth and structuring the phytoplankton community is becoming more evident. However, little is known regarding the extent of micronutrient limitation in freshwaters or which micronutrient conditions favour potentially-toxic cyanobacteria. To assess how freshwater phytoplankton respond to micronutrient and macronutrient additions, we conducted nutrient amendment bioassays at seven sites across South Eastern-Australia. Sites were variable in cyanobacterial cell densities and phytoplankton community compositions. At two sites, Mannus Lake and Burrendong Dam, micronutrient additions (iron, cobalt, copper, manganese, molybdenum and zinc) increased cyanobacterial growth, indicating micronutrient limitation. Both sites had cyanobacterial blooms present at the onset of the experiment, dominated by Chrysosporum ovalisporum at Mannus Lake and Microcystis aeruginosa at Burrendong Dam. This suggests that micronutrients may be an important regulator of the severity of cyanobacterial blooms and may become limiting when there is high competition for nutrient resources. The addition of the micronutrient mixture resulted in a higher proportion of cyanobacteria compared to the control and a lower diversity community compared to phosphorus additions, indicating that micronutrients can not only influence cyanobacterial biovolume but also their ability to dominate the phytoplankton community. This reinforces that micronutrient requirements of phytoplankton are often species specific. As micronutrient enrichment is often overlooked when assessing nutrient-constraints on cyanobacterial growth, this study provides valuable insight into the conditions that may influence cyanobacterial blooms and the potential contribution of micronutrients to eutrophication.
... This study was the first to detect the presence of microcystin in the Amazon River. There have been few previous reports of this toxin in the Amazon region, specifically in the Tapajós River [32] and in the Bolonha Lake in Belém [33,34], but there has been no previous record of microcystin in the Amazon River. These results indicate the need to create a monitoring plan for the catchment area of the DWTP because cyanotoxin concentrations may increase over time and cause health risks to the local population. ...
The aim of the current study is to feature the composition, frequency and richness of cyanobacteria species and their spatial-temporal distribution patterns in Curiaú River. Quarterly collections were carried out at three sampling sites, from June 2016 to October 2017. Phytoplankton and periphyton samples were collected and fixed with Transeau’s solution to be identified under optical microscope. Data were statistically treated through descriptive, variance and cluster analyses; significance level was set at p<0.05. In total, 17 taxa were identified and grouped into four (4) taxonomic orders, namely: Chroococcales, Nostocales, Synechococcales and, most prevalently, Oscillatoriales. Genera Kamptonema (67%) and Phormidium (44%) were the most frequent taxa. Cyanobacteria richness has shown significant variations (p<0.05) among sampling sites. This pattern was not observed for seasonal fluctuations (p> 0.05). These data also represent pioneering information about cyanobacteria biodiversity in Amapá State.
... This study was the first to detect the presence of microcystin in the Amazon River. There have been few previous reports of this toxin in the Amazon region, specifically in the Tapajós River [32] and in the Bolonha Lake in Belém [33,34], but there has been no previous record of microcystin in the Amazon River. These results indicate the need to create a monitoring plan for the catchment area of the DWTP because cyanotoxin concentrations may increase over time and cause health risks to the local population. ...
Human poisoning by microcystin has been recorded in many countries, including Brazil, where fatal cases have already occurred. The Amazon River is the main source of drinking water in municipalities such as Macapá, where there is no monitoring of cyanobacteria and cyanotoxins. This study investigated the presence of cyanobacteria and cyanotoxins in samples from a drinking water treatment plant (DWTP) that catches water from the Amazon River. The toxin analyses employed ELISA, LC/MS, and molecular screening for genes involved in the production of cyanotoxins. The sampling was carried out monthly from April 2015 to April 2016 at the intake (raw water) and exit (treated water) of the DWTP. This study reports the first detection of microcystin-LR (MC-LR) in the Amazon River, the world’s largest river, and in its treated water destined for drinking water purposes in Macapá, Brazil. The cyanobacterial density and MC-LR concentration were both low during the year. However, Limnothrix planctonica showed a density peak (± 900 cells mL −1) in the quarter of June–August 2015, when MC-LR was registered (2.1 µg L −1). Statistical analyses indicate that L. planctonica may produce the microcystin.
... To achieve this goal, the first step was to examine a wide range of environmental and other scientific literature via the Scopus database which includes PubMed, Web of Science and Science Direct. Searches were performed using the following key words: "cyanotoxin", "microcystin", "nodularin", "cylindrospermopsin", "anatoxin", "saxitoxin", and BR mice); 10,900 (Balb/c mice); > 5000 (rats) Rinehart et al. (1988), Sivonen et al. (1992, , Yoshida et al. (1997), Mahakhant et al. (1998, dos Vieira et al. (2003), Ballot (2004), Botha et al. (2004), Ballot et al. (2005) (2-6 days) Ohtani et al. (1992), Li et al. (2001), Schembri et al. (2001), Svrcek and Smith (2004), Spoof et al. (2006), Seifert et al. (2007) Neurotoxins Anatoxin-a/alkaloids Devlin et al. (1977), Carmichael and Gorham (1978), Sivonen et al. (1989), , Fitzgeorge et al. (1994), Ressom et al. (1994, Sivonen and Jones (1999), Ballot (2004), Ballot et al. (2005), Van Apeldoorn et al. (2007), Shams et al. (2015), Carmichael and Boyer (2016) Mahmood and Carmichael (1987), Matsunaga et al. (1989), Carmichael et al. (1990), Stewart (2004 et al. (1994), Mons et al. (1998), Beltran and Neilan (2000), WHO (2003), Pearson et al. (2010), Wiese et al. (2010), Borges et al. (2015), Cirés and Ballot (2016) Dermatotoxins ( ND Fujiki et al. (1983), Moore (1984Moore ( , 1996, Ito et al. (2002), Jiang et al. (2014), Carmichael and Boyer (2016) Aplysiatoxin/phe- Moore et al. (1984), Carmichael and Boyer (2016) 1 3 "poisoning", "intoxication", "incident", "death", "mortality", "health", "health effects", "adverse effects", "exposure", "drinking water", and "recreation". Cyanotoxins are comprised of a wide number of compounds including their structural variants. ...
Cyanobacteria are photoautotrophic organisms which occur in aquatic and terrestrial environments. They have the potential to produce toxins which pose a threat to human and animal health. This review covers the global distribution of the common cyanotoxins and related poisoning cases. A total of 468 selected articles on toxic cyanobacteria, dating from the earliest records until 2018, were reviewed. Most of the articles were published after 2000 (72%; 337 out of 468), which is consistent with the recent growth in interest in the analysis, toxinology and ecotoxicology of cyanotoxins. Animal and/or human poisoning cases were described in more than a third of the overall publications (38%; 177 out of 468). The reviewed publications showed that there were 1118 recorded identifications of major cyanotoxins in 869 freshwater ecosystems from 66 countries throughout the world. Microcystins were the most often recorded cyanotoxins worldwide (63%; 699 out of 1118), followed by cylindrospermopsin (10%; 107 out of 1118), anatoxins (9%; 100 out of 1118), and saxitoxins (8%; 93 out of 1118). Nodularins were the most rarely recorded cyanotoxins (2%; 19 out of 1118); however, there were also reports where cyanotoxins were not analysed or specified (9%; 100 out of 1118). The most commonly found toxic cyanobacterial genera were Microcystis spp. (669 reports), Anabaena spp. (397 reports), Aphanizomenon spp. (100 reports), Planktothrix spp. (98 reports), and Oscillatoria spp. (75 reports). Furthermore, there were 183 recorded cyanotoxin poisonings of humans and/or animals. Out of all toxic cyanobacterial blooms reviewed in this paper, the highest percentage of associated poisonings was found in North and Central America (39%; 69 cases out of 179), then Europe (20%; 35 out of 179), Australia including New Zealand (15%; 27 out of 179), and Africa (11%; 20 out of 179), while the lowest percentage was related to Asia (8%; 14 cases out of 179) and South America (8%; 14 cases out of 179). Events where only animals were known to have been affected were 63% (114 out of 182), whereas 32% (58 out of 182) of the investigated events involved only humans. A historical overview of human and animal poisoning episodes associated with cyanobacterial blooms is presented. Further, geographical data on the occurrence of cyanotoxins and related poisonings based on the available literature are shown. Some countries (mainly European) have done very intensive research on the occurrence of toxic cyanobacteria and cyanotoxins, and reported related ecotoxicological observations, while in some countries the lack of data is apparent. The true global extent of cyanotoxins and associated poisonings is likely to be greater than found in the available literature, and it can be assumed that ecotoxicological and hygienic problems caused by toxic cyanobacteria may occur in more environments.
... Microcystins (MC) and nodularins (NOD), known for their hepatotoxic action, are produced by different strains of Microcystis, Anabaena, Hapalosiphon, Nodularia, Nostoc and Oscillatoria genera. These organisms have been studied as a result of their toxic effects on both animals and humans (Azevedo et al., 2002;Carmichael, T neotropical regions (Fonseca et al., 2011;Jacinavius et al., 2018;Vieira et al., 2003;Sant'Anna et al., 2008). ...
Blooms of cyanobacteria, a common event in eutrophic environments, result in the release of potentially toxic substances into the water. The cyanobacterium Radiocystis fernandoi produces microcystin (MC) and other peptides that may disturb homeostasis. This study evaluated the effect of intraperitoneal injections containing the crude extract (CE) of R. fernandoi strain R28 on the gills and kidneys of neotropical fish, Piaractus mesopotamicus, 3, 6 and 24 h post-injection. CE contained MC-RR, MC-YR and minor other oligopeptides. Plasma ions and the activities of the enzymes PP1 and PP2A, Na+/K+-ATPase (NKA), H+-ATPase (HA) and carbonic anhydrase (CA) were determined and morphological changes in both the gills and kidneys were characterized. Compared to controls, the concentration of Na+ within the plasma of P. mesopotamicus decreased after treatment with CE 3 h post treatment and increased after 24 h; the concentration of K+ decreased after 6 h. The activity of the endogenous PP1 and PP2A was unchanged in the gills and was inhibited in the kidneys 6 h after i.p. injection. In the gills, NKA activity increased after 3 h and decreased 6 h post i.p. exposure. Further, NKA activity did not differ from the controls 24-h post injection. In the kidneys, NKA, HA and CA activities were unaffected by treatment. The mitochondria-rich cell (MRC) density in the gills decreased after 3 h in the filament and 3 and 6 h in the lamellae and was restored to the control levels 24 h post-exposure. Filament epithelial hyperplasia and hypertrophy, lamellar atrophy and rupture of the lamellar epithelium were the most common effects of treatment in the gills. No histopathological changes occurred in the kidneys. This study demonstrates that a single dose of toxic CE from R. fernandoi can cause a transitory ion imbalance in P. mesopotamicus which is related to the changes in MRC levels and NKA activity. Ionic balance was recovered 24 h post i.p. injection, however, morphological changes that occurred in the gills took a longer amount of time to return to normal. To conclude, the effects of components contained within the CE of R. fernandoi may be harmful to P. mesopotamicus. In particular, the recovery of ionic regulation depends on MRC responses and histopathological changes produced by CE may affect gas exchange and other gill functions.
... To achieve this goal, the first step was to examine a wide range of environmental and other scientific literature via the Scopus database which includes PubMed, Web of Science and Science Direct. Searches were performed using the following key words: "cyanotoxin", "microcystin", "nodularin", "cylindrospermopsin", "anatoxin", "saxitoxin", and BR mice); 10,900 (Balb/c mice); > 5000 (rats) Rinehart et al. (1988), Sivonen et al. (1992, , Yoshida et al. (1997), Mahakhant et al. (1998, dos Vieira et al. (2003), Ballot (2004), Botha et al. (2004), Ballot et al. (2005) (2-6 days) Ohtani et al. (1992), Li et al. (2001), Schembri et al. (2001), Svrcek and Smith (2004), Spoof et al. (2006), Seifert et al. (2007) Neurotoxins Anatoxin-a/alkaloids Devlin et al. (1977), Carmichael and Gorham (1978), Sivonen et al. (1989), , Fitzgeorge et al. (1994), Ressom et al. (1994, Sivonen and Jones (1999), Ballot (2004), Ballot et al. (2005), Van Apeldoorn et al. (2007), Shams et al. (2015), Carmichael and Boyer (2016) Mahmood and Carmichael (1987), Matsunaga et al. (1989), Carmichael et al. (1990), Stewart (2004 et al. (1994), Mons et al. (1998), Beltran and Neilan (2000), WHO (2003), Pearson et al. (2010), Wiese et al. (2010), Borges et al. (2015), Cirés and Ballot (2016) Dermatotoxins ( ND Fujiki et al. (1983), Moore (1984Moore ( , 1996, Ito et al. (2002), Jiang et al. (2014), Carmichael and Boyer (2016) Aplysiatoxin/phe- Moore et al. (1984), Carmichael and Boyer (2016) "poisoning", "intoxication", "incident", "death", "mortality", "health", "health effects", "adverse effects", "exposure", "drinking water", and "recreation". Cyanotoxins are comprised of a wide number of compounds including their structural variants. ...
Cyanobacteria are photoautotrophic organisms which occur in aquatic and terrestrial environments. They have the potential to produce toxins which pose a threat to human and animal health. This review covers the global distribution of the common cyanotoxins and related poisoning cases. A total of 468 selected articles on toxic cyanobacteria, dating from the earliest records until 2018, were reviewed. Most of the articles were published after 2000 (72%; 337 out of 468), which is consistent with the recent growth in interest in the analysis, toxinology and ecotoxicology of cyanotoxins. Animal and/or human poisoning cases were described in more than a third of the overall publications (38%; 177 out of 468). The reviewed publications showed that there were 1118 recorded identifications of major cyanotoxins in 869 freshwater ecosystems from 66 countries throughout the world. Microcystins were the most often recorded cyanotoxins worldwide (63%; 699 out of 1118), followed by cylindrospermopsin (10%; 107 out of 1118), anatoxins (9%; 100 out of 1118), and saxitoxins (8%; 93 out of 1118). Nodularins were the most rarely recorded cyanotoxins (2%; 19 out of 1118); however, there were also reports where cyanotoxins were not analysed or specified (9%; 100 out of 1118). The most commonly found toxic cyanobacterial genera were Microcystis spp. (669 reports), Anabaena spp. (397 reports), Aphanizomenon spp. (100 reports), Planktothrix spp. (98 reports), and Oscillatoria spp. (75 reports). Furthermore, there were 183 recorded cyanotoxin poisonings of humans and/or animals. Out of all toxic cyanobacterial blooms reviewed in this paper, the highest percentage of associated poisonings was found in North and Central America (39%; 69 cases out of 179), then Europe (20%; 35 out of 179), Australia including New Zealand (15%; 27 out of 179), and Africa (11%; 20 out of 179), while the lowest percentage was related to Asia (8%; 14 cases out of 179) and South America (8%; 14 cases out of 179). Events where only animals were known to have been affected were 63% (114 out of 182), whereas 32% (58 out of 182) of the investigated events involved only humans. A historical overview of human and animal poisoning episodes associated with cyanobacterial blooms is presented. Further, geographical data on the occurrence of cyanotoxins and related poisonings based on the available literature are shown. Some countries (mainly European) have done very intensive research on the occurrence of toxic cyanobacteria and cyanotoxins, and reported related ecotoxicological observations, while in some countries the lack of data is apparent. The true global extent of cyanotoxins and associated poisonings is likely to be greater than found in the available literature, and it can be assumed that ecotoxicological and hygienic problems caused by toxic cyanobacteria may occur in more environments.
