Seminar of Philippe Le Noac’H
“Performance of phago-mixotrophic nanoplankton vs. resource specialists in a stratified water column under contrasting light-nutrient supply regimes”
Along the opposing vertical gradients of light and nutrients usually present in stratified lakes, nanoplankton phago-mixotrophy represents a generalist resource-acquisition strategy relative to photo-autotrophic or phago-heterotrophic specialist strategies. Yet it is still not entirely clear how phago-mixotrophy can be viable against specialist strategies in a resource competition context. We developed a model that simulates the population dynamics of three nanoplankton competitors (pure photo-autotroph, phago-mixotroph and pure phago-heterotroph) and bacterial prey over the vertical dimension of a stratified water column to investigate the prevalence of phago-mixotrophy. In nature, mixoplankton can be more or less photo-autotrophic, a variability that was incorporated into our model. We used the model to explore how nutrition strategy assemblages shift along gradients of resource availability, and to identify the resource conditions most favorable to phago-mixotrophy. The model also offers insights on how the diversity of nutrition strategies influence the spatial organization of nanoplankton communities in stratified lakes.