Freshwater microbiology : biodiversity and dynamic interactions of microorganisms in the aquatic environment Microbial diversity and freshwater ecosystems Freshwater environments : the influence of physico chemical conditions on microbial communities Algae : the major microbial biomass in freshwater systems Competition for light Inorganic nutrients : uptake and cycling in freshwater systems Bacteria : the main heterotrophic microorganisms in freshwater systems Viruses : major parasites in the freshwater environment Fungi and fungal like organisms : aquatic biota with a mycelial growth form Grazing activities in the freshwater environment : the role of protozoa and invertebrates Eutrophication : the microbial response to high nutrient levels