Detailed observations of the phytoplankton spring bloom in the stratifying central North Sea

摘要

Analysis of detailed time series of bio-optical and temperature data from the North Sea supports the view that a minimum level of turbulence is a prerequisite for the onset and maintenance of the phytoplankton spring bloom in shelf seas, which distinguishes these seas from the open ocean. The start of the spring bloom primarily diatoms is controlled by the light regime while its progress is predominantly dependent upon episodic turbulence input following short periods of stratification, which allow the resuspension of a fast sinking (50-200 m day~-1) phytoplankton community from the bottom mixing layer. A relationship between turbulence and the vertical distribution of phytoplank- ton is proposed which is found at synoptic time scales and on time scales of a day and less.