On the presence of Phalacroma rotundatum in the Southern Adriatic Sea (Italy).

The genus Dinophysis sensu lato is often involved in episodes of Diarrhetic Shellfish Poisoning (DSP) contaminations and human intoxications. To date, several species of this genus have shown toxin production in laboratory, however it is likely that many others could have this capability. Phalacroma rotundatum (Claparède & Lachmann) Kofoid & Michener, allocated by some authors to the genus Dinophysis, is a non-photosynthetic species, which has the potential to produce okadaic acid and its derivatives DTX-1 and DTX-2. This species was observed for the first time along the Southern Adriatic coast of Puglia (Italy) during a two year monitoring program on potentially toxic phytoplankton. Phalacroma rotundatum dynamics was studied in relation to hydrobiological conditions; its seasonal changes appeared rather independent from chemico-physical factors, but were significantly associated with those of phytoflagellates. Toxicity test (Microtox system) on Phalacroma rotundatum cells proved negative.