Abstract
Cytoplasmic feature of Dinophysis fortii, a causative dinoflagellate of DSP in Japan, was investigated using transmission electron microscopy (TEM). Food vacuoles (FV) were observed at both the initial and the final stage of the blooming season in the Sanriku. A large number of mitochondria were found in the FV, indicating that it actively ingested eukaryotes, though prey organisms were not identified. FV was not observed in cells at the middle stage of the bloom when the species was growing actively. In contrast, these cells were rich in chloroplasts, indicating that phototrophy was essential for the species to grow actively, though it can survive under inappropriate growth conditions by preying on other eukaryotes.
