All phytoplankton cells contain chlorophyll

Primary production is the formation of organic carbon from carbon dioxide, using light as an energy source. All phytoplankton cells contain chlorophyll to harvest this light energy. Therefore, chlorophyll might be used to estimate the biomass of phytoplankton. However, the chlorophyll content per cell depends on the available light and the traits of a specific phytoplankton type. The chlorophyll content is therefore dynamically modelled for each phytoplankton type. In spring, diatoms and the Phaeocystis colonies reach the highest production and determine to a large extent phytoplankton biomass and hence, the chlorophyll concentration. Short and sudden changes in the chlorophyll concentrations are caused by large exchanges between Wadden and North Sea, driven by tides (spring tides) and wind (storms).