HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY ANALYSIS OF DIARRHETIC TOXINS IN DINOPHYSIS SPP FROM THE FRENCH COAST

Diarrhetic shellfish poisoning has been a recurrent problem along the Brittany coast (France) since 1983. Okadaic acid (O.A.), the main toxin detected in mussels, is generally associated with the presence of Dinophysis cells in sea water. We report here the results of okadaic acid analyses by high performance liquid chromatography, on planktonic samples collected during the summer of 1991. D. sacculus, the major Dinophysis species, throughout this period, showed low okadaic acid content in raw extract, whereas toxic levels were 3- to 12-fold higher in sorted samples than in raw ones. A maximum O.A. concentration of 29.6 pg cell-1 was found in D. sacculus/D. cf. acuminata extract. Similarly, higher O.A. levels were noted in raw samples when these two species were associated. Generally speaking, variations in raw samples were similar to those in sorted samples. Nevertheless, when D. rotundata reached a concentration equal to that of D. sacculus in sorted samples, the O.A. level was lower.