Ostreopsis cf. ovata bloom in the northern Adriatic Sea during summer 2009: Ecology, molecular characterization and toxin profile

► Ostreopsis cf. ovata bloom did not show any relationship with nutrients. ► Maximum proliferation occurred when temperatures were decreasing. ► A high toxin content per cell was found. Ovatoxin-a dominated in the toxin profile. ► Death of benthic invertebrates occurred during bloom peak. ► Molecular analysis confirmed that only the genotype 'ovata' was present.