The effect of phosphorus supply on the primary production of phytoplankton in the Stechlinsee (GDR)

The effect of phosphorus supply on the primary production in phytoplankton was investigated in the Stechlinsee which is part of the tertiary cooling circuit of the nuclear power plant Rheinsberg. Measurements of the primary production (carbon 14 method), of phosphorus concentration, of light energy and of the uptake of orthophosphate were evaluated from 1970 to 1972. The quality and quantity of phytoplankton was studied in this period. The connection of primary production and supply of phosphates is described for the Stechlinsee on the basis of light energy utilization by phytoplankton in the primary production, of the orthophosphate uptake by the phytoplankton community and of the degree of saturation. The relatioship between exogeneous orthophosphate concentration and the biomass of phytoplankton regulates in connection with the orthophosphate uptake the internal energy effectiveness in the primary production. Statistical evaluations support these results