Includes bibliographical references (p. [495]-516) and index.

Microbial diversity and freshwater ecosystems -- Freshwater environm ents : the influence of physico-chemical conditions on microbial commun ities -- Algae : the major microbial biomass in freshwater systems -- C ompetition for light -- Inorganic nutrients : uptake and cycling in fre shwater systems -- Bacteria : the main heterotrophic microorganisms in freshwater systems -- Viruses : major parasites in the freshwater envir onment -- Fungi and fungal-like organisms : aquatic biota with a myceli al growth form -- Grazing activities in the freshwater environment : th e role of protozoa and invertebrates -- Eutrophication : the microbial response to high nutrient levels.