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Microcystin-producing cyanobacteria identified in Phayao Lake and in Chiang Rai ponds. (A) Oscillatoria spp. (B)
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This study determined the levels of microcystins in water and fish from Phayao Lake, Phayao Province and selected fish ponds along the Ing River tributary in Chiang Rai Province. Samples were collected monthly for 8 months (fish ponds) and were analyzed by HPLC. The highest total micro-cystin-LR levels in water and fish in Phayao Lake were recorded...
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Context 1
... concentrations ranged from ND -5.91 µg· kg -1 dry weight with an average of 1.22 + 0.48 µg·kg -1 dry weight. The highest concentration recorded in fish was in April 2009 (Figure 4). Correlation analysis showed that Microcys- tis species (Microcystis aeruginosa Kütz. ...
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Phytoplankton in an intensive system of white shrimp cultivation is useful as an indicator of the water quality. Blue-green algae are a group of phytoplankton that has an important role, although there are several disserve species. Blue-green algae are an abundant primary producer and can be found a lot both in freshwater and in the sea. Blue-green...
Citations
... When season changes combine with other environmental factors, harmful cyan blooms occur. In Thailand, MC accumulation was found in prawn farms [89,90], fish ponds [90][91][92], and recreational reservoirs [93,94], especially in the temperate region of the country with high N and P concentrations. In contrast, the reports of STX from Thailand were associated with only freshwater puffers [95,96]. ...
The Songkhla Lake Basin (SLB) located in Southern Thailand, has been increasingly polluted by urban and industrial wastewater, while the lake water has been intensively used. Here, we aimed to investigate cyanobacteria and cyanotoxins in the SLB. Ten cyanobacteria isolates were identified as Microcystis genus based on16S rDNA analysis. All isolates harbored microcystin genes, while five of them carried saxitoxin genes. On day 15 of culturing, the specific growth rate and Chl-a content were 0.2–0.3 per day and 4 µg/mL. The total extracellular polymeric substances (EPS) content was 0.37–0.49 µg/mL. The concentration of soluble EPS (sEPS) was 2 times higher than that of bound EPS (bEPS). The protein proportion in both sEPS and bEPS was higher than the carbohydrate proportion. The average of intracellular microcystins (IMCs) was 0.47 pg/cell on day 15 of culturing, while extracellular microcystins (EMCs) were undetectable. The IMCs were dramatically produced at the exponential phase, followed by EMCs release at the late exponential phase. On day 30, the total microcystins (MCs) production reached 2.67 pg/cell. Based on liquid chromatograph-quadrupole time-of-flight mass spectrometry, three new MCs variants were proposed. This study is the first report of both decarbamoylsaxitoxin (dcSTX) and new MCs congeners synthesized by Microcystis.
... Previous studies have revealed blooms of Microcystis, Oscillatoria, Planktolyngbya, Planktotrix and Pseudanabaena in recreational reservoirs in Khon Kaen province in north-eastern Thailand (Somdee et al., 2013). In reservoirs in northern Thailand, blooms of Microcystis aeruginosa resulted in microcystin being found in Nile Tilapia (Oreochromis niloticus) (Aroonvilairat et al., 2004;Seekhao et al., 2007;Whangchai et al., 2013). Studies of eutrophication in Thailand have so far focused on reservoirs (for drinking purposes). ...
... Livestock effluent from the basin and sewage discharges from the city is likely the major pollution sources. These significant sources of nutrients, especially nitrogen and phosphorus, contribute to the eutrophication of the lake [2]. Eutrophication leads to algal blooms and subsequently to taste and odor compounds, geosmin and 2-methylisoborneol (MIB) production, reducing the application of the lake water for drinking and contaminating aquatic animals. ...
... Eutrophication leads to algal blooms and subsequently to taste and odor compounds, geosmin and 2-methylisoborneol (MIB) production, reducing the application of the lake water for drinking and contaminating aquatic animals. Moreover, hepatotoxin microcystin formation in Phayao Lake was also implicated with algal blooms [2]. ...
... Microcystins have also been detected in wild and commercially-raised marine and estuarine mussels (Mytilus trossulus) from Puget Sound, Washington, D.C., U.S.; Nile tilpaia (Oreochromis nitoticus) from Chian Rai, Thailand; and other aquatic foods intended for human consumption [26][27][28]. Routine seawater and aquatic animal monitoring in areas where cyanotoxins have been found could provide early that warning that animal and human shellfish consumers could be at risk. However, the accuracy of detection requires further study, especially when attempting microcystin detection from biological samples [29]. ...
... Recent research demonstrated that microcystins can accumulate in freshwater fish. For example, microcystins were detected in both fresh water samples and fish in aquaculture ponds in Thailand [26]. ...
... Whangchai et al. (2013); Kent et al. (1996); Anderson et al. (1993)[26,52,53] ...
People, domestic animals, and wildlife are all exposed to numerous environmental threats, including harmful algal blooms (HABs). However, because animals exhibit wide variations in diet, land use and biology, they are often more frequently or heavily exposed to HAB toxins than are people occupying the same habitat, making them sentinels for human exposures. Historically, we have taken advantage of unique physiological characteristics of animals, such as the sensitivity of canaries to carbon monoxide, to more quickly recognize threats and help protect human health. As HAB events become more severe and widespread worldwide, exposure and health outcome data for animals can be extremely helpful to predict, prevent, and evaluate human exposures and health outcomes. Applying a One Health approach to investigation of HABs means that lessons learned from animal sentinels can be applied to protect people, animals and our shared environment.
The intricate nature of cyanotoxin exposure through food reveals a complex web of risks and uncertainties in our dietary choices. With the aim of starting to unravel this intricate nexus, a comprehensive review of 111 papers from the past two decades investigating cyanotoxin contamination in food was undertaken. It revealed a widespread occurrence of cyanotoxins in diverse food sources across 31 countries. Notably, 68% of the studies reported microcystin concentrations exceeding established Tolerable Daily Intake levels. Cyanotoxins were detected in muscles of many fish species, and while herbivorous fish exhibited the highest recorded concentration, omnivorous species displayed a higher propensity for cyanotoxin accumulation, exemplified by Oreochromis niloticus. Beyond fish, crustaceans and bivalves emerged as potent cyanotoxin accumulators. Gaps persist regarding contamination of terrestrial and exotic animals and their products, necessitating further exploration. Plant contamination under natural conditions remains underreported, yet evidence underscores irrigation-driven cyanotoxin accumulation, particularly affecting leafy vegetables. Finally, cyanobacterial-based food supplements often harbored cyanotoxins (57 % of samples were positive) warranting heightened scrutiny, especially for Aphanizomenon flos-aquae-based products. Uncertainties surround precise concentrations due to methodological variations (chemical and biochemical) and extraction limitations, along with the enigmatic fate of toxins during storage, processing, and digestion. Nonetheless, potential health consequences of cyanotoxin exposure via contaminated food include gastrointestinal and neurological disorders, organ damage (e.g. liver, kidneys, muscles), and even elevated cancer risks. While microcystins received significant attention, knowledge gaps persist regarding other cyanotoxins' accumulation, exposure, and effects, as well as combined exposure via multiple pathways. Intriguing and complex, cyanotoxin exposure through food beckons further research for our safer and healthier diets.
Cyanotoxins have gained global public interest due to their potential to bioaccumulate in food, which threatens human health. Bloom formation is usually enhanced under Mediterranean, subtropical and tropical climates which are the dominant climate types in developing countries. In this context, we present an up-to-date overview of cyanotoxins (types, toxic effects, analysis, occurrence, and mitigation) with a special focus on their contamination in (sea)food from all the developing countries in Africa, Asia, and Latin America as this has received less attention. A total of 65 publications have been found (from 2000 until October 2021) reporting the contamination by one or more cyanotoxins in seafood and edible plants (five papers). Only Brazil and China conducted more research on cyanotoxin contamination in food in comparison to other countries. The majority of research focused on the detection of microcystins using different analytical methods. The detected levels mostly surpassed the provisional tolerable daily intake limit set by the World Health Organization, indicating a real risk to the exposed population. Assessment of cyanotoxin contamination in foods from developing countries still requires further investigations by conducting more survey studies, especially the simultaneous detection of multiple categories of cyanotoxins in food.
Cyanotoxins are toxic and are found in eutrophic, municipal and residential water supplies. For this reason, their occurrence in drinking water systems has become a global concern. Therefore, monitoring, control, risk assessment, and prevention of these contaminants in the environmental bodies are important subjects associated with public health. Thus, rapid, sensitive, selective, simple and accurate analytical methods for the identification and determination of cyanotoxins are required. In this article, the sampling methodologies and applications of solid phase based sample preparation methods for the determination of cyanotoxins in environmental matrices are reviewed. The sample preparation techniques mainly include solid phase microextraction (SPME), solid phase extraction (SPE) and solid phase adsorption toxin tracking technology (SPATT). In addition, advantages and disadvantages and future prospects of these methods have been discussed.
This study aimed to determine the species of cyanobacteria in rainy and winter season which affect the water quality of Phayao Lake. The study was carried out in six collection points (3, adjacent to the city; and the other 3, adjacent to the agricultural areas) across the lake. Water samples were collected monthly from July 2012 to February 2013. Results showed that cyanobacteria dominated the lake at every sampling point with significantly higher numbers (P<0.05) recorded in the rainy season than in winter. Four genera of cyanobacteria were identified as the most frequently encountered groups, namely: Microcystis aeruginosa, M. wesenbergii, Anabaena sp. and Oscillatoria sp. Furthermore, at KP3 point (water supply pumping area) the number of M. aeruginosa genera (producers of hepatotoxin compounds) and, Anabaena sp. and Oscillatoria sp. (producers of off-flavor compounds) were found to be the most dominant. Water supply from Phayao Lake in rainy season should be therefore carefully checked and monitored regularly for quality (especially for drinking purposes) due to the possibility of contamination from cyanobacterial secondary metabolites which include earthy–musty taste and odor compounds and hepatotoxins microcystins.
