A study on Ostreopsis cf. ovata along the eastern Adriatic coast

The marine benthic dinoflagellate genus Ostreopsis is known to produce a range of ovatoxins and palytoxins the most potent non- protein marine toxins known so far Presence and related harmful algal blooms of Ostreopsis species are documented in the Adriatic Sea. Negative impacts on marine benthic organism as well as on human health are recorded. Still, an extensive approach to Ostreopsis research is missing for the eastern Adriatic. This study delivers detailed information about the distribution and genetic identification of the genus Ostreopsis along the eastern Adriatic coast. This is also the first information on Ostreopsis for the south-eastern (SE) Adriatic. Bloom periods were observed at the end of summer with higher abundances recorded in the north than in the south Adriatic. All sampled Ostreopsis populations were determined to be the species Ostreopsis cf. ovata by light microscopy and DNA based analysis. Furthermore, all populations along the north-eastern (NE) Adriatic coast share the ITS1-5.8S-ITS2-28S genotype, identical with most of the populations recorded around the Mediterranean. The spread of O. cf. ovata along the eastern Adriatic coast recorded in this paper indicates high potential of Ostreopsis blooms to form with even small scale and localized favourable conditions possibly allowing blooms with harmful effects on human health