First evidence of okadaic acid in Mytilus galloprovincialis mussels, collected in a Mediterranean Lagoon, Tunisia.

Evidence of the presence of okadaic acid (OA) and its monthly fluctuations are reported for the first time in Mytilus galloprovincialis samples collected from June 2005 to May 2006 in the Bizerte Lagoon. All of the samples with the exception of those taken in August 2005 were found to be contaminated. The level of OA in mussels exceeded the regulatory limit of DSP toxins (16 microg OA/100 g mussel meat) within the European Union (2002) in only two cases: in January and February, 2006 with 31.85 +/- 3.06, and 18.86 +/- 1.88 microg OA/100 g mussel meat respectively. During the investigative period, potentially toxic dinoflagellates were observed. The results reported here, although based on limited sampling, demonstrate for the first time the existence of a risk to public health from diarrheic shellfish poisoning in cultivated bivalve mollusc in Tunisia.