Taxonomic assessment of a toxic cyanobacteria shift in hypereutrophic Grand Lake St. Marys (Ohio, USA).

Highlights: [•] Persistent toxic cyanobacterial blooms in Grand Lake St. Marys (Ohio, USA) have been attributed to toxic Planktothrix spp. that produce microcystins. [•] Phylogenetic analysis of mcyA (gene microcystin synthetase subunit A) during the 2010 revealed a toxic population of Microcystis spp. in July. [•] Despite the abundance and dominance of Planktothrix spp. in the lake, the July Microcystis spp. population likely contributed most of the toxin. [•] Understanding taxonomic shifts in cyanobacterial populations during bloom events is necessary when developing abatement strategies. [ABSTRACT FROM AUTHOR]