Competition for Light between Toxic and Nontoxic Strains of the Harmful Cyanobacterium MicrocystisContrasting microcystin production and cyanobacterial population dynamics in two Planktothrix dominated freshwater lakesToxic and nontoxic Microcystis colonies in natural populations can be differentiated on the basis of rRNA gene internal transcribed spacer diversityMicrocystis genotype succession in relation to microcystin concentrations in freshwater lakesComposition of the bacterial community degrading Phaeocystis mucopolysaccharides in enrichment culturesA simple remedy against artifactual double bands in denaturing gradient gel electrophoresisHigh-resolution differentiation of cyanobacteria by using rRNA-Internal Transcribed Spacer denaturing gradient gel electrophoresis