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Seasonal Dynamics of Microcystis spp. and Their Toxigenicity as Assessed by qPCR in a Temperate Reservoir
CIIMAR/CIMAR, Marine and Environmental Research Centre, Porto University, Rua dos Bragas, 289, Porto 4050-123, Portugal
Department of Biology, Faculty of Sciences, Porto University, Rua do Campo Alegre, Porto 4069-007, Portugal
CISA/Research Centre in Environment and Health, School Health Technology of Oporto, Polytechnic Institute of Porto, Rua de Valente Perfeito, 322, Gaia 440-330, Portugal
* Author to whom correspondence should be addressed.
Received: 26 August 2011; in revised form: 15 September 2011 / Accepted: 26 September 2011 / Published: 29 September 2011
Abstract: Blooms of toxic cyanobacteria are becoming increasingly frequent, mainly due to water quality degradation. This work applied qPCR as a tool for early warning of microcystin(MC)-producer cyanobacteria and risk assessment of water supplies. Specific marker genes for cyanobacteria, Microcystis and MC-producing Microcystis, were quantified to determine the genotypic composition of the natural Microcystis population. Correlations between limnological parameters, pH, water temperature, dissolved oxygen and conductivity and MC concentrations as well as Microcystis abundance were assessed. A negative significant correlation was observed between toxic (with mcy genes) to non-toxic (without mcy genes) genotypes ratio and the overall Microcystis density. The highest proportions of toxic Microcystis genotypes were found 4–6 weeks before and 8–10 weeks after the peak of the bloom, with the lowest being observed at its peak. These results suggest positive selection of non-toxic genotypes under favorable environmental growth conditions. Significant positive correlations could be found between quantity of toxic genotypes and MC concentration, suggesting that the method applied can be useful to predict potential MC toxicity risk. No significant correlation was found between the limnological parameters measured and MC concentrations or toxic genotypes proportions indicating that other abiotic and biotic factors should be governing MC production and toxic genotypes dynamics. The qPCR method here applied is useful to rapidly estimate the potential toxicity of environmental samples and so, it may contribute to the more efficient management of water use in eutrophic systems.
Keywords: microcystins; Microcystis; qPCR; water quality monitoring; water management
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Martins, A.; Moreira, C.; Vale, M.; Freitas, M.; Regueiras, A.; Antunes, A.; Vasconcelos, V. Seasonal Dynamics of Microcystis spp. and Their Toxigenicity as Assessed by qPCR in a Temperate Reservoir. Mar. Drugs 2011, 9, 1715-1730.
Martins A, Moreira C, Vale M, Freitas M, Regueiras A, Antunes A, Vasconcelos V. Seasonal Dynamics of Microcystis spp. and Their Toxigenicity as Assessed by qPCR in a Temperate Reservoir. Marine Drugs. 2011; 9(10):1715-1730.
Martins, António; Moreira, Cristiana; Vale, Micaela; Freitas, Marisa; Regueiras, Ana; Antunes, Agostinho; Vasconcelos, Vitor. 2011. "Seasonal Dynamics of Microcystis spp. and Their Toxigenicity as Assessed by qPCR in a Temperate Reservoir." Mar. Drugs 9, no. 10: 1715-1730.