First report of potentially microcystin-producing Microcystis in the Dominican Republic.

When the amount of nutrients in water bodies increases, cyanobacteria tend to proliferate rapidly in freshwater lakes and reservoirs, which can trigger cyanobacterial blooms. This increases the risk of cyanotoxin generation in water sources intended for human consumption, crop irrigation, and livestock. This study focused on identifying the presence of cyanobacteria and cyanotoxins in the Valdesia reservoir, which supplies drinking water to approximately 4 million people in Santo Domingo, Azua, San Cristóbal, San José de Ocoa, and Peravia in the Dominican Republic. Morphological observation suggested the presence of the genus Microcystis, which was confirmed by amplification and sequencing of two fragments of the 16S rRNA gene, as well as a fragment of the mcyA gene involved in encoding microcystins. This is the first report to highlight the urgent need to establish continuous monitoring of potentially microcystins-producing Microcystis sp. in this important reservoir, to implement appropriate water management measures to prevent their negative impact on public health and the environment.