Correlation of the Seasonal and Annual Variation of Phytoplankton Biomass in Dutch Coastal Waters of the North Sea with Rhine River Discharge

Water quality parameters of the Dutch rivers and of Dutch coastal waters of the North Sea have been monitored regularly for many years by the Dutch government agency “Rijkswaterstaat”. The results have been published every 3 months in a series of reports, from which we have compiled the concentrations of nutrients in the Dutch part of the river Rhine and of chlorophyll in Dutch coastal waters measured between 1972 and 1986. The purpose was to find trends in eutrophication and to analyse how the pelagic ecosystem of the North Sea, and especially the basis of this system, the phytoplankton, responds to the expected annual variability in eutrophication.