Free Standard AU & NZ Shipping For All Book Orders Over $80!
Register      Login
Marine and Freshwater Research Marine and Freshwater Research Society
Advances in the aquatic sciences
RESEARCH ARTICLE

Survey of microcystins in Singapore’s reservoirs using liquid chromatography–tandem mass spectrometry (LC-MS/MS)

Cristina Porojan A D , Feras Abbas A , Maxine A. D. Mowe B , Mary Lehane A , Simon M. Mitrovic B C , Richard P. Lim C , Darren C. J. Yeo B and Ambrose Furey A
+ Author Affiliations
- Author Affiliations

A Mass Spectrometry Research Group, Department of Physical Sciences, Cork Institute of Technology (CIT), Bishopstown, Cork, T12 P928, Ireland.

B Freshwater and Invasion Biology Laboratory, Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543, Republic of Singapore.

C Freshwater and Estuarine Research Group, School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia.

D Corresponding author. Email: cristina.porojan@mycit.ie

Marine and Freshwater Research 71(5) 659-672 https://doi.org/10.1071/MF18432
Submitted: 8 November 2018  Accepted: 22 November 2019   Published: 31 January 2020

Abstract

Microcystins (MCs) are a group of toxins produced by certain cyanobacteria that occur naturally in fresh waters and can cause acute poisoning in humans and animals. Because cyanobacteria have been found in the freshwater reservoirs of Singapore, a comprehensive survey for cyanotoxins was undertaken over a 12-month period in 17 reservoirs from November 2012 to October 2013. For the quantitative analysis of the reservoir samples, an liquid chromatography–tandem mass spectrometry (LC-MS/MS) method was developed that targeted the following hepatotoxins: MC-LR, MC-RR, MC-LW, MC-LF, MC-WR and MC-LY. The most prevalent MC variants identified were MC-LR and MC-RR. Results showed that the level of intracellular MC-LR in the raw or untreated water was close to the World Health Organisation (WHO) provisional MC-LR drinking water guideline of 1 μg L–1 for 1 of 200 samples tested (0.8 μg L–1), and that intracellular MC concentrations were above 0.3 μg L–1 in samples collected from four reservoirs. Based on random forest analysis, total monthly rainfall and total nitrogen concentrations were found to be the most important factors affecting intracellular MC concentrations for these four reservoirs. The toxin levels for the other reservoirs were relatively low compared with the WHO provisional MC-LR guideline limit of 1.0 μg L–1.

Additional keywords: cyanobacterial blooms, hepatotoxins, intracellular toxin levels, tropical.


References

Ahn, C.-Y., Chung, A.-S., and Oh, H.-M. (2002). Rainfall, phycocyanin, and N : P ratios related to cyanobacterial blooms in a Korean large reservoir. Hydrobiologia 474, 117–124.
Rainfall, phycocyanin, and N : P ratios related to cyanobacterial blooms in a Korean large reservoir.Crossref | GoogleScholarGoogle Scholar |

American Public Health Association, American Water Works Association and Water Environment Federation (2012). ‘Standard Methods for the Examination of Water and Wastewater’, 22nd edn. (APHA: Washington DC, USA.)

Azevedo, S. M. F. O., Carmichael, W. W., Jochimsen, E. M., Rinehart, K. L., Lau, S., Shaw, G. R., and Eaglesham, G. K. (2002). Human intoxication by microcystins during renal dialysis treatment in Caruaru–Brazil. Toxicology 181–182, 441–446.
Human intoxication by microcystins during renal dialysis treatment in Caruaru–Brazil.Crossref | GoogleScholarGoogle Scholar |

Bellinger, E. G., and Sigee, D. C. (2015). ‘Freshwater Algae: Identification, Enumeration and Use as Bioindicators.’ (Wiley: Hoboken, NJ, USA.)

Bláha, L., Babica, P., and Maršálek, B. (2009). Toxins produced in cyanobacterial water blooms-toxicity and risks. Interdisciplinary Toxicology 2, 36–41.
Toxins produced in cyanobacterial water blooms-toxicity and risks.Crossref | GoogleScholarGoogle Scholar | 21217843PubMed |

Botana, L. M. (2014). ‘Seafood and Freshwater Toxins: Pharmacology, Physiology, and Detection.’ (CRC Press: Boca Raton, FL, USA.)

Cadel-Six, S., Moyenga, D., Magny, S., Trotereau, S., Edery, M., and Krys, S. (2014). Detection of free and covalently bound microcystins in different tissues (liver, intestines, gills, and muscles) of rainbow trout (Oncorhynchus mykiss) by liquid chromatography–tandem mass spectrometry: method characterization. Environmental Pollution 185, 333–339.
Detection of free and covalently bound microcystins in different tissues (liver, intestines, gills, and muscles) of rainbow trout (Oncorhynchus mykiss) by liquid chromatography–tandem mass spectrometry: method characterization.Crossref | GoogleScholarGoogle Scholar | 24316797PubMed |

Campbell, K., Vilariño, N., Botana, L. M., and Elliott, C. T. (2011). A European perspective on progress in moving away from the mouse bioassay for marine-toxin analysis. Trends in Analytical Chemistry 30, 239–253.
A European perspective on progress in moving away from the mouse bioassay for marine-toxin analysis.Crossref | GoogleScholarGoogle Scholar |

Carmichael, W. (1992). Cyanobacteria secondary metabolites – the cyanotoxins. The Journal of Applied Bacteriology 72, 445–459.
Cyanobacteria secondary metabolites – the cyanotoxins.Crossref | GoogleScholarGoogle Scholar | 1644701PubMed |

Carmichael, W. (2008). A world overview – one-hundred-twenty-seven years of research on toxic cyanobacteria – where do we go from here? In ‘Cyanobacterial Harmful Algal Blooms: State of the Science and Research Needs’. (Ed. H. K. Hudnell.) pp. 105–125. (Springer: New York, NY, USA.)

Carmichael, W. W., Azevedo, S., An, J. S., Molica, R., Jochimsen, E. M., Lau, S., Rinehart, K. L., Shaw, G. R., and Eaglesham, G. K. (2001). Human fatalities from cyanobacteria: chemical and biological evidence for cyanotoxins. Environmental Health Perspectives 109, 663–668.
Human fatalities from cyanobacteria: chemical and biological evidence for cyanotoxins.Crossref | GoogleScholarGoogle Scholar | 11485863PubMed |

Chatziefthimiou, A. D., Metcalf, J. S., Glover, W. B., Banack, S. A., Dargham, S. R., and Richer, R. A. (2016). Cyanobacteria and cyanotoxins are present in drinking water impoundments and groundwater wells in desert environments. Toxicon 114, 75–84.
Cyanobacteria and cyanotoxins are present in drinking water impoundments and groundwater wells in desert environments.Crossref | GoogleScholarGoogle Scholar | 26921462PubMed |

Chew, N. (1976). Some growth studies on three freshwater phytoplankters from a tropical reservoir. M.Sc. Dissertation, National University of Singapore.

Chidambara Raj, C. B., Kwong, T. E., Shi, S., and Num, P. A. (2008). Dissolved organic carbon and potential for disinfection byproducts in Kranji, Pandan and Tengah reservoirs in Singapore. Water Science and Technology: Water Supply 8, 413–419.
Dissolved organic carbon and potential for disinfection byproducts in Kranji, Pandan and Tengah reservoirs in Singapore.Crossref | GoogleScholarGoogle Scholar |

Chorus, E. I., and Bartram, J. (1999). Toxic cyanobacteria in water: a guide to their public health consequences, monitoring and management. (World Health Organisation.) Available at https://apps.who.int/iris/handle/10665/42827 [Verified 8 January 2020].

Clements, R., Koh, L. P., Lee, T. M., Meier, R., and Li, D. (2006). Importance of reservoirs for the conservation of freshwater molluscs in a tropical urban landscape. Biological Conservation 128, 136–146.
Importance of reservoirs for the conservation of freshwater molluscs in a tropical urban landscape.Crossref | GoogleScholarGoogle Scholar |

Codd, G. A., Bell, S. G., Kaya, K., Ward, C. J., Beattie, K. A., and Metcalf, J. S. (1999). Cyanobacterial toxins, exposure routes and human health. European Journal of Phycology 34, 405–415.
Cyanobacterial toxins, exposure routes and human health.Crossref | GoogleScholarGoogle Scholar |

DeVries, S., Galey, F., Namikoshi, M., and Woo, J. (1993). Clinical and pathologic findings of blue–green algae (Microcystis aeruginosa) intoxication in a dog. Journal of Veterinary Diagnostic Investigation 5, 403–408.
Clinical and pathologic findings of blue–green algae (Microcystis aeruginosa) intoxication in a dog.Crossref | GoogleScholarGoogle Scholar | 8373855PubMed |

Dietrich, D. R., Fischer, A., Michel, C., and Höger, S. J. (2008). ‘Toxin Mixture in Cyanobacterial Blooms – a Critical Comparison of Reality with Current Procedures Employed in Human Health Risk Assessment.’ (Springer: Berlin, Germany)

Downing, J., McClain, M., Twilley, R., Melack, J., Elser, J., Rabalais, N., Lewis, W., Turner, R., Corredor, J., and Soto, D. (1999). The impact of accelerating land-use change on the N-cycle of tropical aquatic ecosystems: current conditions and projected changes. Biogeochemistry 46, 109–148.
The impact of accelerating land-use change on the N-cycle of tropical aquatic ecosystems: current conditions and projected changes.Crossref | GoogleScholarGoogle Scholar |

Ferrão-Filho, A. S., and Kozlowsky-Suzuki, B. (2011). Cyanotoxins: bioaccumulation and effects on aquatic animals. Marine Drugs 9, 2729–2772.
Cyanotoxins: bioaccumulation and effects on aquatic animals.Crossref | GoogleScholarGoogle Scholar |

Fitzgeorge, R., Clark, S., and Keevil, C. (1994). Routes of intoxication. Special Publication – Royal Society of Chemistry 149, 69–74.

Freitas, E. C., Pinheiro, C., Rocha, O., and Loureiro, S. (2014). Can mixtures of cyanotoxins represent a risk to the zooplankton? The case study of Daphnia magna Straus exposed to hepatotoxic and neurotoxic cyanobacterial extracts. Harmful Algae 31, 143–152.
Can mixtures of cyanotoxins represent a risk to the zooplankton? The case study of Daphnia magna Straus exposed to hepatotoxic and neurotoxic cyanobacterial extracts.Crossref | GoogleScholarGoogle Scholar | 28040103PubMed |

Furey, A., Crowley, J., Hamilton, B., Lehane, M., and James, K. J. (2005). Strategies to avoid the mis-identification of anatoxin-a using mass spectrometry in the forensic investigation of acute neurotoxic poisoning. Journal of Chromatography A 1082, 91–97.
Strategies to avoid the mis-identification of anatoxin-a using mass spectrometry in the forensic investigation of acute neurotoxic poisoning.Crossref | GoogleScholarGoogle Scholar | 16038198PubMed |

Gardner, W. S., Cavaletto, J. F., Bootsma, H. A., Lavrentyev, P. J., and Troncone, F. (1998). Nitrogen cycling rates and light effects in tropical Lake Maracaibo, Venezuela. Limnology and Oceanography 43, 1814–1825.
Nitrogen cycling rates and light effects in tropical Lake Maracaibo, Venezuela.Crossref | GoogleScholarGoogle Scholar |

Gilroy, D. J., Kauffman, K. W., Hall, R. A., Huang, X., and Chu, F. S. (2000). Assessing potential health risks from microcystin toxins in blue–green algae dietary supplements. Environmental Health Perspectives 108, 435–439.
Assessing potential health risks from microcystin toxins in blue–green algae dietary supplements.Crossref | GoogleScholarGoogle Scholar | 10811570PubMed |

Gin, K. Y.-H., Ramaswamy, U., and Gopalakrishnan, A. P. (2011). Comparison of nutrient limitation in freshwater and estuarine reservoirs in tropical urban Singapore. Journal of Environmental Engineering 137, 913–919.
Comparison of nutrient limitation in freshwater and estuarine reservoirs in tropical urban Singapore.Crossref | GoogleScholarGoogle Scholar |

Harada, K.-I., Tsuji, K., Watanabe, M. F., and Kondo, F. (1996). Stability of microcystins from cyanobacteria – III. Effect of pH and temperature. Phycologia 35, 83–88.
Stability of microcystins from cyanobacteria – III. Effect of pH and temperature.Crossref | GoogleScholarGoogle Scholar |

Hecky, R., Mugidde, R., Ramlal, P., Talbot, M., and Kling, G. (2010). Multiple stressors cause rapid ecosystem change in Lake Victoria. Freshwater Biology 55, 19–42.
Multiple stressors cause rapid ecosystem change in Lake Victoria.Crossref | GoogleScholarGoogle Scholar |

Ho, T. K. (1995). Random decision forests. In ‘Proceedings of the 3rd International Conference on Document Analysis and Recognition’, 14–16 August 1995, Montreal, QC, Canada. pp. 278–282. (IEEE.)10.1109/ICDAR.1995.598994

Jacoby, J., Burghdoff, M., Williams, G., Read, L., and Hardy, F. J. (2015). Dominant factors associated with microcystins in nine midlatitude, maritime lakes. Inland Waters 5, 187–202.
Dominant factors associated with microcystins in nine midlatitude, maritime lakes.Crossref | GoogleScholarGoogle Scholar |

Jayatissa, L., Silva, E., McElhiney, J., and Lawton, L. (2006). Occurrence of toxigenic cyanobacterial blooms in freshwaters of Sri Lanka. Systematic and Applied Microbiology 29, 156–164.
Occurrence of toxigenic cyanobacterial blooms in freshwaters of Sri Lanka.Crossref | GoogleScholarGoogle Scholar | 16464697PubMed |

Jewel, M., Affan, M., and Khan, S. (2003). Fish mortality due to cyanobacterial bloom in an aquaculture pond in Bangladesh. Pakistan Journal of Biological Sciences 6, 1046–1050.

Jochimsen, E. M., Carmichael, W. W., An, J., Cardo, D. M., Cookson, S. T., Holmes, C. E., Antunes, M. B., de Melo Filho, D. A., Lyra, T. M., and Barreto, V. S. T. (1998). Liver failure and death after exposure to microcystins at a hemodialysis center in Brazil. The New England Journal of Medicine 338, 873–878.
Liver failure and death after exposure to microcystins at a hemodialysis center in Brazil.Crossref | GoogleScholarGoogle Scholar | 9516222PubMed |

Jones, G. J., and Poplawski, W. (1998). Understanding and management of cyanobacterial blooms in sub-tropical reservoirs of Queensland, Australia. Water Science and Technology 37, 161–168.
Understanding and management of cyanobacterial blooms in sub-tropical reservoirs of Queensland, Australia.Crossref | GoogleScholarGoogle Scholar |

Kaloudis, T., Zervou, S.-K., Tsimeli, K., Triantis, T. M., Fotiou, T., and Hiskia, A. (2013). Determination of microcystins and nodularin (cyanobacterial toxins) in water by LC–MS/MS. Monitoring of Lake Marathonas, a water reservoir of Athens, Greece. Journal of Hazardous Materials 263, 105–115.
Determination of microcystins and nodularin (cyanobacterial toxins) in water by LC–MS/MS. Monitoring of Lake Marathonas, a water reservoir of Athens, Greece.Crossref | GoogleScholarGoogle Scholar | 23958137PubMed |

Kebede, E., and Belay, A. (1994). Species composition and phytoplankton biomass in a tropical African lake (Lake Awassa, Ethiopia). Hydrobiologia 288, 13–32.
Species composition and phytoplankton biomass in a tropical African lake (Lake Awassa, Ethiopia).Crossref | GoogleScholarGoogle Scholar |

Khoo, T. C. (2009). Singapore water: yesterday, today and tomorrow. In ‘Water Management in 2020 and Beyond’. (Eds A. K. Biswas, C. Tortajada, and R. Izquierdo) pp. 237–250. (Springer-Verlag: Berlin, Germany.)

Khoo, H.-W., Yang, S.-L., and Goh, C.-J. (1977). A preliminary limnological study of Seletar Reservoir. Journal of the Singapore National Academy of Science 6, 1–12.

Koreivienė, J., and Belous, O. (2012). Methods for cyanotoxins detection. Botanica Lithuanica 18, 58–65.
Methods for cyanotoxins detection.Crossref | GoogleScholarGoogle Scholar |

Kuiper-Goodman, T., Miller, J., and Trenholm, H. (1994). Prevention of human mycotoxicoses through risk assessment and risk management. In ‘Mycotoxins in Grain: Compounds Other Than Aflatoxin’. (Eds J. D. Miller and H. L. Trenholm.) pp. 439–469. (Eagon Press: Saint Paul, MN, USA.)

Lance, E., Petit, A., Sanchez, W., Paty, C., Gérard, C., and Bormans, M. (2014). Evidence of trophic transfer of microcystins from the gastropod Lymnaea stagnalis to the fish Gasterosteus aculeatus. Harmful Algae 31, 9–17.
Evidence of trophic transfer of microcystins from the gastropod Lymnaea stagnalis to the fish Gasterosteus aculeatus.Crossref | GoogleScholarGoogle Scholar | 28040116PubMed |

Lewis, W. (2010). Biogeochemistry of tropical lakes. Internationale Vereinigung für theoretische und angewandte Limnologie: Verhandlungen 30, 1595–1603.

Lian, J., Yao, Y., Ma, C., and Guo, Q. (2014). Reservoir operation rules for controlling algal blooms in a tributary to the impoundment of Three Gorges Dam. Water (Basel) 6, 3200–3223.
Reservoir operation rules for controlling algal blooms in a tributary to the impoundment of Three Gorges Dam.Crossref | GoogleScholarGoogle Scholar |

Merel, S., Walker, D., Chicana, R., Snyder, S., Baures, E., and Thomas, O. (2013). State of knowledge and concerns on cyanobacterial blooms and cyanotoxins. Environment International 59, 303–327.
State of knowledge and concerns on cyanobacterial blooms and cyanotoxins.Crossref | GoogleScholarGoogle Scholar | 23892224PubMed |

Meriluoto, J., and Codd, G. A. (2005). Cyanobacterial monitoring and cyanotoxin analysis. Acta Academiae Aboensis 65, 1–145.

Metcalf, J. S., Richer, R., Cox, P. A., and Codd, G. A. (2012). Cyanotoxins in desert environments may present a risk to human health. The Science of the Total Environment 421–422, 118–123.
Cyanotoxins in desert environments may present a risk to human health.Crossref | GoogleScholarGoogle Scholar | 22369867PubMed |

Monchamp, M.-E., Pick, F. R., Beisner, B. E., and Maranger, R. (2014). Nitrogen forms influence microcystin concentration and composition via changes in cyanobacterial community structure. PLoS One 9, e85573.
Nitrogen forms influence microcystin concentration and composition via changes in cyanobacterial community structure.Crossref | GoogleScholarGoogle Scholar | 24427318PubMed |

Mowe, M. A., Mitrovic, S. M., Lim, R. P., Furey, A., and Yeo, D. C. (2015a). Tropical cyanobacterial blooms: a review of prevalence, problem taxa, toxins and influencing environmental factors. Journal of Limnology 74, 205–224.
Tropical cyanobacterial blooms: a review of prevalence, problem taxa, toxins and influencing environmental factors.Crossref | GoogleScholarGoogle Scholar |

Mowe, M. A., Porojan, C., Abbas, F., Mitrovic, S. M., Lim, R. P., Furey, A., and Yeo, D. C. (2015b). Rising temperatures may increase growth rates and microcystin production in tropical Microcystis species. Harmful Algae 50, 88–98.
Rising temperatures may increase growth rates and microcystin production in tropical Microcystis species.Crossref | GoogleScholarGoogle Scholar |

Mowe, M. A., Abbas, F., Porojan, C., Mitrovic, S. M., Lim, R. P., Furey, A., and Yeo, D. C. (2016). Roles of nitrogen and phosphorus in growth responses and toxin production (using LC-MS/MS) of tropical Microcystis ichthyoblabe and M. flos-aquae. Journal of Applied Phycology 28, 1543–1552.
Roles of nitrogen and phosphorus in growth responses and toxin production (using LC-MS/MS) of tropical Microcystis ichthyoblabe and M. flos-aquae.Crossref | GoogleScholarGoogle Scholar |

Neffling, M.-R., Spoof, L., Quilliam, M., and Meriluoto, J. (2010). LC–ESI-Q-TOF-MS for faster and accurate determination of microcystins and nodularins in serum. Journal of Chromatography – B. Analytical Technologies in the Biomedical and Life Sciences 878, 2433–2441.
LC–ESI-Q-TOF-MS for faster and accurate determination of microcystins and nodularins in serum.Crossref | GoogleScholarGoogle Scholar | 20724233PubMed |

Nguyen, L. T. T., Cronberg, G., Annadotter, H., and Larsen, J. (2007). Planktic cyanobacteria from freshwater localities in ThuaThien-Hue Province, Vietnam. II. Algal biomass and microcystin production. Nova Hedwigia 85, 35–49.
Planktic cyanobacteria from freshwater localities in ThuaThien-Hue Province, Vietnam. II. Algal biomass and microcystin production.Crossref | GoogleScholarGoogle Scholar |

Nguyen, V. T., Gin, K. Y.-H., Reinhard, M., and Liu, C. (2012). Occurrence, fate, and fluxes of perfluorochemicals (PFCs) in an urban catchment: Marina Reservoir, Singapore. Water Science and Technology 66, 2439–2446.
Occurrence, fate, and fluxes of perfluorochemicals (PFCs) in an urban catchment: Marina Reservoir, Singapore.Crossref | GoogleScholarGoogle Scholar | 23032776PubMed |

Okello, W., Ostermaier, V., Portmann, C., Gademann, K., and Kurmayer, R. (2010). Spatial isolation favours the divergence in microcystin net production by Microcystis in Ugandan freshwater lakes. Water Research 44, 2803–2814.
Spatial isolation favours the divergence in microcystin net production by Microcystis in Ugandan freshwater lakes.Crossref | GoogleScholarGoogle Scholar | 20219228PubMed |

Orihel, D. M., Bird, D. F., Brylinsky, M., Chen, H., Donald, D. B., Huang, D. Y., Giani, A., Kinniburgh, D., Kling, H., and Kotak, B. G. (2012). High microcystin concentrations occur only at low nitrogen-to-phosphorus ratios in nutrient-rich Canadian lakes. Canadian Journal of Fisheries and Aquatic Sciences 69, 1457–1462.
High microcystin concentrations occur only at low nitrogen-to-phosphorus ratios in nutrient-rich Canadian lakes.Crossref | GoogleScholarGoogle Scholar |

Ortea, P. M., Allis, O., Healy, B. M., Lehane, M., Shuilleabháin, A. N., Furey, A., and James, K. J. (2004). Determination of toxic cyclic heptapeptides by liquid chromatography with detection using ultra-violet, protein phosphatase assay and tandem mass spectrometry. Chemosphere 55, 1395–1402.
Determination of toxic cyclic heptapeptides by liquid chromatography with detection using ultra-violet, protein phosphatase assay and tandem mass spectrometry.Crossref | GoogleScholarGoogle Scholar | 15081782PubMed |

Ozawa, K., Fujioka, H., Muranaka, M., Yokoyama, A., Katagami, Y., Homma, T., Ishikawa, K., Tsujimura, S., Kumagai, M., Watanabe, M. F., and Park, H. D. (2005). Spatial distribution and temporal variation of Microcystis species composition and microcystin concentration in Lake Biwa. Environmental Toxicology 20, 270–276.
Spatial distribution and temporal variation of Microcystis species composition and microcystin concentration in Lake Biwa.Crossref | GoogleScholarGoogle Scholar | 15892068PubMed |

Paerl, H. W., and Huisman, J. (2008). Blooms like it hot. Science 320, 57–58.
Blooms like it hot.Crossref | GoogleScholarGoogle Scholar | 18388279PubMed |

Paerl, H. W., and Huisman, J. (2009). Climate change: a catalyst for global expansion of harmful cyanobacterial blooms. Environmental Microbiology Reports 1, 27–37.
Climate change: a catalyst for global expansion of harmful cyanobacterial blooms.Crossref | GoogleScholarGoogle Scholar | 23765717PubMed |

Paerl, H. W., and Paul, V. J. (2012). Climate change: links to global expansion of harmful cyanobacteria. Water Research 46, 1349–1363.
Climate change: links to global expansion of harmful cyanobacteria.Crossref | GoogleScholarGoogle Scholar | 21893330PubMed |

Paerl, H. W., Hall, N. S., Peierls, B. L., and Rossignol, K. L. (2014). Evolving paradigms and challenges in estuarine and coastal eutrophication dynamics in a culturally and climatically stressed world. Estuaries and Coasts 37, 243–258.
Evolving paradigms and challenges in estuarine and coastal eutrophication dynamics in a culturally and climatically stressed world.Crossref | GoogleScholarGoogle Scholar |

Pan, G., Zhang, M.-M., Chen, H., Zou, H., and Yan, H. (2006a). Removal of cyanobacterial blooms in Taihu Lake using local soils. I. Equilibrium and kinetic screening on the flocculation of Microcystis aeruginosa using commercially available clays and minerals. Environmental Pollution 141, 195–200.
Removal of cyanobacterial blooms in Taihu Lake using local soils. I. Equilibrium and kinetic screening on the flocculation of Microcystis aeruginosa using commercially available clays and minerals.Crossref | GoogleScholarGoogle Scholar | 16236411PubMed |

Pan, G., Zou, H., Chen, H., and Yuan, X. (2006b). Removal of harmful cyanobacterial blooms in Taihu Lake using local soils III. Factors affecting the removal efficiency and an in situ field experiment using chitosan-modified local soils. Environmental Pollution 141, 206–212.
Removal of harmful cyanobacterial blooms in Taihu Lake using local soils III. Factors affecting the removal efficiency and an in situ field experiment using chitosan-modified local soils.Crossref | GoogleScholarGoogle Scholar | 16214277PubMed |

Paul, V. J. (2008). Global warming and cyanobacterial harmful algal blooms. In ‘Cyanobacterial Harmful Algal Blooms: State of the Science and Research Needs’. (Ed. H. K. Hudnell.) pp. 239–257. (Springer: Berlin, Germany)

Pekar, H., Westerberg, E., Bruno, O., Lääne, A., Persson, K. M., Sundström, L. F., and Thim, A.-M. (2016). Fast, rugged and sensitive ultra high pressure liquid chromatography tandem mass spectrometry method for analysis of cyanotoxins in raw water and drinking water – first findings of anatoxins, cylindrospermopsins and microcystin variants in Swedish source waters and infiltration ponds. Journal of Chromatography. A 1429, 265–276.
Fast, rugged and sensitive ultra high pressure liquid chromatography tandem mass spectrometry method for analysis of cyanotoxins in raw water and drinking water – first findings of anatoxins, cylindrospermopsins and microcystin variants in Swedish source waters and infiltration ponds.Crossref | GoogleScholarGoogle Scholar | 26755412PubMed |

Pham, M. N., Tan, H. T., Mitrovic, S., and Yeo, H. H. (2011). ‘A Checklist of the Algae of Singapore.’ (Raffles Museum of Biodiversity Research, National University of Singapore: Singapore.)

Pham, T.-L., Dao, T.-S., Tran, N.-D., Nimptsch, J., Wiegand, C., and Motoo, U. (2017). Influence of environmental factors on cyanobacterial biomass and microcystin concentration in the Dau Tieng Reservoir, a tropical eutrophic water body in Vietnam. International Journal of Limnology 53, 89–100.
Influence of environmental factors on cyanobacterial biomass and microcystin concentration in the Dau Tieng Reservoir, a tropical eutrophic water body in Vietnam.Crossref | GoogleScholarGoogle Scholar |

Pouria, S., de Andrade, A., Barbosa, J., Cavalcanti, R. L., Barreto, V. T. S., Ward, C. J., Preiser, W., Poon, G. K., Neild, G. H., and Codd, G. A. (1998). Fatal microcystin intoxication in haemodialysis unit in Caruaru, Brazil. Lancet 352, 21–26.
Fatal microcystin intoxication in haemodialysis unit in Caruaru, Brazil.Crossref | GoogleScholarGoogle Scholar | 9800741PubMed |

Prommana, R., Peerapornpisal, Y., Whangchai, N., Morrison, L. F., Metcalf, J. S., Ruangyuttikarn, W., Towprom, A., and Codd, G. (2006). Microcystins in cyanobacterial blooms from two freshwater prawn (Macrobrachium rosenbergii) ponds in Northern Thailand. ScienceAsia 32, 365–370.
Microcystins in cyanobacterial blooms from two freshwater prawn (Macrobrachium rosenbergii) ponds in Northern Thailand.Crossref | GoogleScholarGoogle Scholar |

Puddick, J., Prinsep, M. R., Wood, S. A., Kaufononga, S. A., Cary, S. C., and Hamilton, D. P. (2014). High levels of structural diversity observed in microcystins from Microcystis CAWBG11 and characterization of six new microcystin congeners. Marine Drugs 12, 5372–5395.
High levels of structural diversity observed in microcystins from Microcystis CAWBG11 and characterization of six new microcystin congeners.Crossref | GoogleScholarGoogle Scholar | 25402827PubMed |

Rantala, A., Rajaniemi-Wacklin, P., Lyra, C., Lepistö, L., Rintala, J., Mankiewicz-Boczek, J., and Sivonen, K. (2006). Detection of microcystin-producing cyanobacteria in Finnish lakes with genus-specific microcystin synthetase gene E (mcyE) PCR and associations with environmental factors. Applied and Environmental Microbiology 72, 6101–6110.
Detection of microcystin-producing cyanobacteria in Finnish lakes with genus-specific microcystin synthetase gene E (mcyE) PCR and associations with environmental factors.Crossref | GoogleScholarGoogle Scholar | 16957235PubMed |

Reichwaldt, E. S., and Ghadouani, A. (2012). Effects of rainfall patterns on toxic cyanobacterial blooms in a changing climate: between simplistic scenarios and complex dynamics. Water Research 46, 1372–1393.
Effects of rainfall patterns on toxic cyanobacterial blooms in a changing climate: between simplistic scenarios and complex dynamics.Crossref | GoogleScholarGoogle Scholar | 22169160PubMed |

Sim, J. (2009). Isolation of different cyanobacteria types from Singapore reservoirs. B.Eng.(Hons) Thesis, National University of Singapore.

Sitoki, L., Kurmayer, R., and Rott, E. (2012). Spatial variation of phytoplankton composition, biovolume, and resulting microcystin concentrations in the Nyanza Gulf (Lake Victoria, Kenya). Hydrobiologia 691, 109–122.
Spatial variation of phytoplankton composition, biovolume, and resulting microcystin concentrations in the Nyanza Gulf (Lake Victoria, Kenya).Crossref | GoogleScholarGoogle Scholar | 24683268PubMed |

Smith, V. H., Tilman, G. D., and Nekola, J. C. (1999). Eutrophication: impacts of excess nutrient inputs on freshwater, marine, and terrestrial ecosystems. Environmental Pollution 100, 179–196.
Eutrophication: impacts of excess nutrient inputs on freshwater, marine, and terrestrial ecosystems.Crossref | GoogleScholarGoogle Scholar | 15093117PubMed |

Spoof, L., and Catherine, A. (2016). Appendix 3: tables of microcystins and nodularins. In ‘Handbook of Cyanobacterial Monitoring and Cyanotoxin Analysis’. (Eds J. Meriluoto, L. Spoof, and G. A. Codd.) pp. 526–537. (Wiley.)

Taranu, Z. E., Gregory-Eaves, I., Steele, R. J., Beaulieu, M., and Legendre, P. (2017). Predicting microcystin concentrations in lakes and reservoirs at a continental scale: A new framework for modelling an important health risk factor. Global Ecology and Biogeography 26, 625–637.
Predicting microcystin concentrations in lakes and reservoirs at a continental scale: A new framework for modelling an important health risk factor.Crossref | GoogleScholarGoogle Scholar |

Te, S. H., and Gin, K. Y.-H. (2011). The dynamics of cyanobacteria and microcystin production in a tropical reservoir of Singapore. Harmful Algae 10, 319–329.
The dynamics of cyanobacteria and microcystin production in a tropical reservoir of Singapore.Crossref | GoogleScholarGoogle Scholar |

Watanabe, M. F., Harada, K.-I., Matsuura, K., Watanabe, M., and Suzuki, M. (1989). Heptapeptide toxin production during the batch culture of two Microcystis species (Cyanobacteria). Journal of Applied Phycology 1, 161–165.
Heptapeptide toxin production during the batch culture of two Microcystis species (Cyanobacteria).Crossref | GoogleScholarGoogle Scholar |

Welker, M., Chorus, I., and Fastner, J. (2004). Occurrence of cyanobacterial toxins (microcystins) in surface waters of rural Bangladesh – pilot study. Report WHO/SDE/WSH/04.06. (Water, Sanitation and Health Protection of the Human Environment, World Health Organisation: Geneva, Switzerland.) Available at https://apps.who.int/iris/bitstream/handle/10665/68699/WHO_SDE_WSH_04.06.pdf?sequence=1&isAllowed=y [Verified 8 January 2020].

White, S. H., Fabbro, L. D., and Duivenvoorden, L. J. (2003). Changes in cyanoprokaryote populations, Microcystis morphology, and microcystin concentrations in Lake Elphinstone (Central Queensland, Australia). Environmental Toxicology 18, 403–412.
Changes in cyanoprokaryote populations, Microcystis morphology, and microcystin concentrations in Lake Elphinstone (Central Queensland, Australia).Crossref | GoogleScholarGoogle Scholar | 14608610PubMed |

Wong, Y. T., Lim, Y. M., and Chiam-Tai, Y. C. (2011). ‘A Guide to Freshwater Phytoplankton in Singapore Reservoirs.’ (Singapore Science Centre: Singapore.)

World Health Organisation (2003). Cyanobacterial toxins: microcystin-LR in drinking-water. Background document for development of WHO Guidelines for Drinking-water Quality. WHO/SDE/WSH/03.04/57. WHO, Geneva, Switzerland.

Xie, L., Rediske, R. R., Gillett, N. D., O’Keefe, J. P., Scull, B., and Xue, Q. (2016). The impact of environmental parameters on microcystin production in dialysis bag experiments. Scientific Reports 6, 38722.
The impact of environmental parameters on microcystin production in dialysis bag experiments.Crossref | GoogleScholarGoogle Scholar | 27934931PubMed |

Yang, S., and Tai, Y. (1991). Algae and algal blooms in Singapore reservoirs. Public Utilities Board Research and Development Journal 5, 17–27.

Yuan, L. L., Pollard, A. I., Pather, S., Oliver, J. L., and D’Anglada, L. (2014). Managing microcystin: identifying national-scale thresholds for total nitrogen and chlorophyll a. Freshwater Biology 59, 1970–1981.
Managing microcystin: identifying national-scale thresholds for total nitrogen and chlorophyll a.Crossref | GoogleScholarGoogle Scholar |

Zanchett, G., and Oliveira-Filho, E. C. (2013). Cyanobacteria and cyanotoxins: from impacts on aquatic ecosystems and human health to anticarcinogenic effects. Toxins 5, 1896–1917.
Cyanobacteria and cyanotoxins: from impacts on aquatic ecosystems and human health to anticarcinogenic effects.Crossref | GoogleScholarGoogle Scholar | 24152991PubMed |

Zeng, Y., Chong, K. Y., Grey, E. K., Lodge, D. M., and Yeo, D. C. J. (2015). Disregarding human pre-introduction selection can confound invasive crayfish risk assessments. Biological Invasions 17, 2373–2385.
Disregarding human pre-introduction selection can confound invasive crayfish risk assessments.Crossref | GoogleScholarGoogle Scholar |

Zervou, S.-K., Christophoridis, C., Kaloudis, T., Triantis, T. M., and Hiskia, A. (2017). New SPE-LC-MS/MS method for simultaneous determination of multi-class cyanobacterial and algal toxins. Journal of Hazardous Materials 323, 56–66.
New SPE-LC-MS/MS method for simultaneous determination of multi-class cyanobacterial and algal toxins.Crossref | GoogleScholarGoogle Scholar | 27453259PubMed |