The wax and wane of <i>Phaeocystis globosa</i> blooms

Phaeocystís globoso spring blooms start when daily irradiance exceeds 100 W h m 2 day t and diploid flagellates in a non-turbulent environment transform into non-flagellate cells and produce the first colony stage. In the colonies the nonflagellate cells grow rapidly under ample nutrient (N, P, 81, C) conditions, are not grazed, and compete with diatoms by raising the seawater pH. Once a nutrient is depleted the colony structure weakens and the non-flagellate cells disappear through grazing, lysis or by transforming into two morphologicaliy different haploid flagellates. The latter occurs when daily irradiance is less then 100 W h m 2 dayt, the result of sinking towards the seabed. The haploid microand mesoflagellates leave behind a ghost colony. The fusion of the micro- and the mesoflagellate produces a diploid macroflagellate, the inoculum for the next bloom. ... Zie: Summar