• algal and bacterial production;
  • exudation;
  • bactivorous metazoans and protozoans;
  • microbial web;
  • feeding rate


During 1989 and 1990 the carbon dynamics in the shallow eutrophic Lake Müggelsee (Berlin) were investigated by analysing the seasonal succession of phytoplankton, metazooplankton, protozooplankton and bacteria. Size fractionated algal primary production and exudation were measured as well as bacterial production in order to calculate the amount of carbon covering the bacterial carbon demand by primary production. The impact of bacterivorous protozoans and metazoans was estimated by comparison of the calculated feeding rate and the bacterial production. Our results show a shift within the metabolic interactions of the microbial food web from winter/spring to summer, indicating a high significance of the protozooplankton as a regulator on bacteria during the colder season, whereas from early summer the influence of metazooplankton dominated by cladocerans was evident in this eutrophic lake.