Inter-Research
Aquatic Microbial Ecology

ABSTRACT: Some aspects of the life-cycle have been investigated in Dinophysis cf. acuminata, the dominant species of the genus along the French Atlantic coast, as well as in D. acuta; a few observations have also been made on the Mediterranean species D. pavillardi. Dinophysis cells occur in 2 clearly distinguished sizes. Small cells typically had a theca thinner than large cells, and cingular and sulcal lists were less developed. Both small and large cells were seen dividing, producing 1 to 4 round intracellular bodies. Some of these round bodies in turn contained many small flagellated cells which escaped through a pore and swam rapidly. Their behaviour after release, and how they might give rise to vegetative cells, has not been observed thus far; we do not believe they are fungal parasites. We propose the following hypothesis to explain our observations: round-shaped bodies, formed inside the vegetative cells, produce small, motile zoids. These zoids grow and are transformed into apparently vegetativeforms, which later act as gametes. Soon after conjugation, the zygote encysts, sometimes after the first or the second division. This working hypothesis, however, requires further elucidation and confirmation using different approaches.

KEY WORDS: Dinophysis sp. . Life cycle . Cyst

Published in AME Vol. 9, No. 2 (1995) on August 31
Print ISSN: 0948-3055; Online ISSN: 1616-1564. Copyright © Inter-Research, Oldendorf/Luhe, 1995