Dynamics of planktic microorganisms and viruses in the littoral zone of the Rybinsk Reservoir: Influence of water-bird colonies.

The influence of gull and heron colonies on the dynamics of heterotrophic bacteria, flagellates, and viruses in the coastal waters of the Rybinsk Reservoir is studied. The littoral zone of the reservoir is found to contain abundant microorganisms and virioplankton. The specifics of the seasonal dynamics of these components of the microbial community in the areas colonized by water birds are revealed. An increase in the abundance and biomass of bacteria has been found in open coastal waters near a heron colony, but not in the background biotope. Maximum values of these parameters are recorded in the protected part of the littoral near the nesting area of gulls. During the period of strong ornithogenic pressure, the abundance of microorganisms and viruses is higher in areas located near water-bird colonies. It is shown that gulls have the greatest influence on the microbial planktic community in the protected littoral zone separated from the open part of the reservoir and characterized by high concentrations of soluble organic compounds and nitrogen. [ABSTRACT FROM AUTHOR]