Colony growth and evidence for colony multiplication in Phaeocystis pouchetii (Prymnesiophyceae) isolated from mesocosm blooms

Using well plates of Phaeocystis pouchetii colonies isolated from experimental mesocosms in western Norway, increases in colony size and division were documented. Median, longest linear dimensions increased 0-7 μm h -1 ; literature Phamcystis globosa values are 0.9-4.7 μm h -1 . Ten to twelve percent of colonies divided at rates of 0.21-0.28 divisions day -1 . Daughter colonies were 100 μm smaller than mother colonies. Colonies delayed 3.5-4.9 days to first division, compared with literature values of 4-5 days for P. globosa. This study provides the first experimental evidence for colony division of wild P. pouchetii.