Royal Netherlands Institute for Sea Research

Phaeocystis globosa

80.000 cells per millilitre...

Once the diatoms have utilized all silicate, the small Haptophyta Phaeocystis globosa takes its chance and starts to reproduce at a very high rate. Within a matter of days the water can be filled with young spherical colonies of this species. Each tiny spot on the photo represents one Phaeocystis cell. Although present concentrations are already impressive (80.000 cells per ml), they used to be even higher during the 1980s (190.000 cells per ml in 1985). In addition of being the most numerous species in the Marsdiep, Phaeocystis also represents most of the annual phytoplankton biomass.