Adult oysters Crassostrea gigas were experimentally fed with Alexandrium catenella and
Alexandrium minutum which are responsible for recurrent toxic blooms in French coastal waters.
C. gigas produced faeces and pseudofaeces containing intact and viable temporary
pellicular cysts of these two Paralytic toxin producing species. When
incubated in favourable conditions, these pellicular cysts were able to
germinate at high rates (between 74 and 94%) and the resulting vegetative
cells divided with growth rates close to the non- ingested cells (control).
The toxin profile of the vegetative cells originated from the germinated
temporary cysts was analyzed by liquid chromatography/fluorescence
detection. Total toxin content of newly germinated cells was lower than that
of cultured cells. Besides, cell contents of C2, B1, B2 and dcGTX3 toxins
featured some changes. Our results suggest that the increased spreading of
toxic dinoflagellates through the transfer of shellfish from contaminated
towards pristine coastal areas cannot be ruled out. We also suggest that
pellicular cysts and newly germinated cells could represent a potential way
for the transfer of paralytic toxins toward the higher trophic levels.