Effect of food quantity and quality on the growth and survival of European perch and roach early juveniles

Young-of-the-year perch and roach dominate the 0+ fish communities of meso- to eutrophic temperate water bodies across Europe. General succession from dominance of perch to roach with increasing ecosystem productivity has been documented for lakes of different trophic status and when comparing fish community structure within reservoirs with pronounced longitudinal gradients. Better competitive abilities of juvenile roach for crustaceoplankton have been suggested as responsible for these changes. But recently, higher efficiency of roach for copepod or cladoceran prey was doubted and therefore our aim was to clarify the effect of interspecific foraging competition of juvenile roach on perch in manipulative enclosure experiments, that were particularly focused on the effect of food quantity and quality (prey taxa, prey size, prey biomass, foraging deprivations, timing of diet shifts etc.) on the changes in competitive success (evaluated as realized growth) between both species.