Morphology, Relative DNA Content and Hypothetical Life Cycle of Phaeocystis Pouchetii (Prymnesiophyceae); with Special Emphasis on the Flagellated Cell Type

The flagellated stage in the genus Phaeocystis has only been described in a few studies and its significance in nature is poorly understood. A flagellated cell type of P. pouchetii was isolated from Raunefjorden (western Norway) and described for the first time by transmission electron microscopy and light microscopy studies. The present study shows that the flagellated cell type of P. pouchetii is morphologically different from other Phaeocystis species. Two types of body scales were found, which were different from those described for other species within the genus. The flagellated cells observed in this study produce pentagonal stars, implying only one type of flagellated cell. The ultrastructure of the flagellated cell type is also presented. Flow cytometric analysis of the relative DNA content of the flagellated and the non-motile coccoid colony cell types revealed similar amounts of DNA in the different cell types. No ploidy differences in the two cell types of P. pouchetii were thus shown under the current investigation. Based on the results obtained and literature information, a hypothetical life cycle for P. pouchetii is presented.