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

Intense blooms of the benthic dinoflagellate Ostreopsis cf. ovata occur in the northern Adriatic Sea since 2006. These blooms are associated with noxious effects on human health and mortality of benthic organisms due to the production of palytoxin-like compounds. The O. cf. ovata bloom and its relationships with nutrient concentrations at 2 stations on the Conero Riviera (N Adriatic Sea) was investigated in summer 2009. O. cf. ovata developed from August to November, with the highest abundances in September (1.3x106 cells g-1fw corresponding to 63.8x103 cells cm-2). The presence of the single O. cf. ovata genotype was confirmed by the PCR assay. Bloom developed when the seawater temperature was decreasing. Nutrient concentrations did not seem to affect bloom dynamics. Toxin analysis performed by high resolution liquid chromatography-mass spectrometry revealed a high total toxin content (up to 75 pg cell-1), including putative palytoxin and all the ovatoxins known so far