Successful cultivation of the toxic dinoflagellate Dinophysis caudata (Dinophyceae)

Recently, Park et al. (2006) succeeded in cultivating the toxic dinoflagellate Dinophysis acuminata and maintaining them by feeding the ciliate Myrionecta rubra grown with a cryptophyte Teleaulax sp. After this report, the present study is the second report of propagation of a Dinophysis species (Dinophysis caudata) under laboratory condi- tions and describes the maintenance of several clonal strains kept at high abundance (� 5,000 cells mL � 1 ) for a rela- tively long period (� 4 months) when fed on M. rubra with the addition of Teleaulax amphioxeia. We confirmed that D. caudata swam actively around its ciliate prey and inserted its peduncle (feeding tube) into the ciliate. Thereafter, the prey became immobile and rounded. Dinophysis caudata actively ingested the cytoplasm of the prey through the pedun- cle. Dinophysis caudata grew at a growth rate of 1.03 divisions day � 1 when supplied with M. rubra as prey, reaching a maximum concentration of ca. 5,000 cell well � 1 (810 mL) during a 9 day growth experiment. In contrast, a culture of D. caudata was not able to be established in the absence of the ciliate or when provided with T. amphioxeia only, suggest- ing that D. caudata can not directly utilize T. amphioxeia as prey.