Seasonal changes in the abundance and production of epilimnetic bacterioplankton, protistan abundance and bacterivory, and extracellular phytoplankton production (EPP) were studied at 3 sampling stations (DAM, MIDDLE and RIVER) located along the longitudinal axis of the canyon-shaped, meso-eutrophic Rimov reservoir (Czech Republic). We found that at the river inflow (RIVER) compared to lacustrine parts of the reservoir (MIDDLE and DAM), different sources of organic carbon and of bacterial mortality control bacterioplankton dynamics and community composition. At the RIVER site, EPP accounted for a negligible part of bacterial carbon demand, thus indicating the prominent role of allochthonous sources of organic substrates in the river inflow. In addition, protistan bacterivory removed there, on average, only 9 % of bacterial production. In contrast, at the lacustrine MIDDLE and DAM stations, protistan bacterivory accounted for 47 and 78 % of bacterial production, respectively. Moreover, at these stations EPP was an autochthonous source of organic carbon sufficient to meet bacterial carbon demand and EPP was tightly correlated with bacterial carbon demand (DAM, r(2) = 0.589, p