DSP toxin profile in the coastal waters of the central Adriatic Sea

A monitoring program, carried out in 1996 and 1997, has confirmed that toxic compounds, other than the most frequently detected toxins okadaic acid (OA) and dinophysistoxin-1 (DTX-1), are involved in DSP phenomena in the Adriatic Sea. Toxicity was assessed by the mouse bioassay; the content and the nature of the toxic components were established through fluorometric HPLC analysis combined with mass spectrometry. A rare pectenotoxin-2 (PTX-2) derivative, 7-epi-pectenotoxin-2 seco acid (7-epi-PTX-2SA), was the exclusive contaminant of samples collected from the central Adriatic in 1996. Contrary to its marked oral toxicity, intraperitoneally 7-epi-PTX-2SA displayed no toxic effects, hampering its detection by the mouse bioassay. In 1997, its concentration and frequency of appearance were lower than in 1996, with concomitant occurrence of OA, DTX-2, and a new unidentified component related to the DSP toxic group of compounds. This is the first report on the occurrence of DTX-2 in Adriatic mussels. A survey of the phytoplankton community in the surrounding seawater has established the presence of Prorocentrum micans and several potentially toxic species from the Dinophysis genus. A case of unexplained toxicity, associated with the occurrence of Gonyaulax polyedra, suggested possible shellfish contamination with yessotoxin (YTX).