Net primary production (mgC/m2/d)
Period: 03-Jan-1989-31-Dec-1989 Ave/Gridpoint=513.099

New phytoplankton biomass

Net primary production is the production of new phytoplankton biomass. It is the gross production minus excretion and respiration.
The figure above shows that the production is higher near the coast than in off-shore areas. The high production in the Southern North Sea along the coast is caused by Pheaocystis. These algae can reach very high concentrations through colonies formation which are too large for grazing by mesozooplankton. The relative high production south of Norway is caused by local conditions in the Skagerrak and the Norwegian Trench (clear, deep water, rocky coasts very small tidal currents and relatively high nutrient levels) and the fact that we dynamically modelled the chlorophyll content, resulting in primary production down to 50 meter. The low production in the Northern off-shore part of the North Sea is caused by relatively low nutrient concentration, a smaller growing season and the stable vertical stratifications.