Evidence of yessotoxins in Alfacs Bay- toxic effect evaluation by cell-based assays and toxin profile determination by liquid chromatography

Abstract

In July 2005 a bloom of the dinoflagellate Protoceratium reticulatum at cell concentrations of 1600 cells.L-1 was detected in Alfacs Bay, located in the northwestern Mediterranean, concomitant with the presence of Dinophysis sacculus. Positive DSP mouse bioassay measurements from samples from the bay indicated the presence of diarrhetic toxins in mussels. Analytical procedures have been optimised and applied to phytoplankton and mussel extracts. Mussel samples were first extracted in methanol/H2O (80:20), further percolated through an octadecylsilica cartridge, derivatized using the dienophile fluorescence reagent, DMEQ-TAD, and subsequently analysed by LC-FD. Yessotoxins in mussels were detected during this event at concentrations of 16-50 μg.kg-1. Phytoplankton samples were extracted by sonication with methanol followed by a clean-up step. Okadaic acid concentration levels in these samples were also studied to confirm the toxic effects recorded along the bloom of P. reticulatum and D. sacculus. Evaluation of cell-based toxicity of field samples through estimation of cell viability and morphological effects was studied and compared to the analytical measurements