Feeding behaviour of Fragilidium cf. duplocampanaeforme and F. subglobosum on four Dinophysis species

We studied the feeding behaviour of several Fragilidium strains of F. duplocampanaeforme and F. subglobosum from the Atlantic, NW Iberian coast, towards four Dinophysis species (D. acuminata, D. acuta, D. caudata and D. tripos). LC-MS analyses were performed to follow the fate of toxins in the water or their transference from Dinophysis cells to Fragilidium. Different feeding behaviour and mechanisms were observed among the Fragilidium strains: F. duplocampanaeforme fed upon D. acuminata and D. caudata but not on D. acuta and weakly on D. tripos. Fragilidium engulfed these preys directly through the sulcus as previously described. Allelopathic effects toward certain but not all Dinophysis species studied were observed. Frequency of gamete-like small forms of F. duplocampanaeforme was much higher (>50%) in cultures preying on Dinophysis (D. acuminata and D. caudata) than in those (