Seasonal variation of phytoplankton populations and primary production in the Sluice dock at Ostend (Belgium)

The Sluice Dock at Ostend has been investigated for phytoplankton populations and primary production for the years 1971 and 1972. Nannoplankton is demonstrated to take a prominent part in pelagic primary production. The seasonal cycle shows a short spring outburst of Eutreptiella marina da Cunha followed by a depressed production period (May). Summer is the most productive; several nannoplankton populations appear successively in this period. The depression in May is discussed in relation to zooplankton activity.