Numerical modelling of the planktonic succession in a nutrient-rich reservoir: environmental and physiological factors leading to Microcystis aeruginosa dominance

The purpose of this study is to shed light on some important factors that allow the strong development of one cyanobacteria, Microcystis aeruginosa, in a man-made lake (Villerest, Loire, France). A numerical 1D-vertical model of the phytoplanktonic succession has been developed. It allows us to simulate the temporal and spatial variations in concentration of the main phytoplanktonic species in relation to the vertical mixing processes in the reservoir. Our results show that the buoyancy regulation of M. aeruginosa is a major factor in its dominance in the lake, at least when the water column is well stratified.