Contamination en dinophysistoxines des moules de Bretagne sud Mise en évidence des dérivés acyls-esters de l'acide okadaïque (DTX-3) Etude comparative : analyses chimiques, tests biologiques et concentrations cellulaires de Dinophysis

Ifremer monitoring network for phytoplankton and phycotoxins (REPHY) is in charge of shellfish safety control and carries out shellfish toxicity test on mice as soon as Dinophysis cells (okadaic acid "OA" producer) are observed in sea water. However, this test can neither identify or quantify the diarrhetic toxins OA and its analogues (DTX-1, DTX-3). Only a chemical analysis is able to detect them. At first, the shellfish extraction procedure used for mouse-tests was optimised in order to adjust it for OA/DTX-1 chemical analysis. Due to the Iack of standard, DTX-3 quantification is clone indirectly after a hydrolysis stage releasing OA. Chemical analysis of shellfish samples collected in 2001 from three locations of "Long-line Mussel Farming" of southern Brittany reveals, in addition to OA, in one band, the presence of DTX-3 ranging from 50% to 100% of the total OA quantity ; and in other band, the absence of DTX-1. Shellfish contamination by Dinophysis takes approximately one week. Furthermore, data collected in this study indicate a close relationship between Dinophysis cell count variations, mussel toxicity mouse-tests and [OA + DTX-3] concentration.