the North Sea during the spring of 1996 and 1997. The paper elaborates the differences of
uptake rates of oxidised nitrogen (NO3−) and reduced nitrogen (NH4 and urea) by
Phaeocystis and diatoms. The nitrogen concentrations were dominated by NO3− with a
maximum concentration of 30 μM (January 1997) and 40 μM (March 1996). In 1996,
Phaeocystis dominated the spring biomass with a maximum of 521 μg C l− 1, while …