Monitoring microcystin-LR-producing cyanobacterial bloom in La Purísima Dam in Guanajuato, Mexico

Toxic cyanobacterial blooms are a growing concern due to their increasing frequency. The presence of cyanotoxins, classified as emerging contaminants, in freshwater sources poses a serious threat to aquatic ecosystems and human health. Understanding the levels of cyanotoxins in water bodies is essential for ensuring public well-being and the availability of this vital resource. In Guanajuato, the water from dams and reservoirs is primarily used for crop irrigation, as well as for recreational activities and fishing. La Purisima Dam is a Protected Natural Area with a background of eutrophication and home to migratory birds. This study reports the presence of Planktothrix, Microcystis and Raphidiopsis. The genes mcyC, mcyD, Cyr, and sxtA, which are involved in the synthesis of microcystins, cylindrospermopsin and saxitoxin, were detected at DNA level, and MC-LR was quantified.