PLANKTON DEVELOPMENT IN A RAPIDLY FLUSHED LAKE IN THE RIVER SPREE SYSTEM (NEUENDORFER SEE, NORTHEAST GERMANY)

The Neuendorfer See is a shallow lake through which the River Spree fl ows. In the lake, abundances of zooplankton (mainly rotifers) and phyt oplankton increased exponentially over the Bowing stretch between the inflow and the outflow of the river. Increase in space is enhanced by increased residence time in the lake. Sensitivity of plankton developm ent on residence times of <8 days weakened at longer residence times. This pattern holds for all zooplankton species. Rates of change in chl orophyll and rotifers (after correction for temperature) are first enh anced, then are decreased at longer residence times. Concentrations of dissolved inorganic nutrients [Si, soluble reactive phosphorus (SRP) and NO3-] and the NIP ratio diminished with increasing residence time. The plankton dynamics in the lake were dependent on discharge and the lake behaved as a 'plug flow tubular reactor' with minor longitudinal mixing. This was not different from the transportation in large river s.