Respostas da comunidade zooplanct？nica à forma？？o do reservatório de Dona Francisca, Rio Grande do Sul, Brasil

we investigated the changes in species richness, density and composition of the zooplankton community in response to the formation of a reservoir in the area of the dona francisca hydroelectric plant. zooplankton samples were collected quarterly over four years, comprising two years before and two years after the formation of the reservoir. species richness and density of cladocera, copepoda and rotifera increased after the filling of the reservoir. further, the zooplankton community showed a clear change in species composition between the periods before and after the formation of the reservoir. the distinct species composition between the two periods was related to changes in limnological characteristics due to the formation of the reservoir.