Abstract
Many observations carried out in several fish ponds (Dombes and Centre areas, France) confirm that the planktonic cladoceran Bosmina longirostris constitutes a large fraction of the zooplankton and the most important part of the cladocerans (60 to 80%). During summer, populations often are up to several thousands 1 -1 , and up to several hundreds 1 -1 during winter in fertilized ponds. Environmental conditions are very favourable for this species. There is no competition with large cladocerans eliminated by fish predation, and phytoplankton blooms reduce water transparency; so B. longirostris can more easily escape to fish predation. In fish ponds, predators of B. longirostris are chiefly carnivorous copepods. Fish do not consume B. longirostris in the water column, but this species after its death can constitute an appreciable source of food for many species of fish, when the dead bodies have settled on the bottom.
Published Version
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