Efeito de herbívoros aquáticos sobre a estrutura e a dinâmica da comunidade de algas perifíticas.

Abstract

The effect of aquatic herbivores on the richness, abundance and dynamics of periphytic algae community is the first study in the floodplain of the upper Paraná River, to be evaluated by means of experiments and in situ microcosms (aquariums 300L). For this, we used as substrates culms, in a period of low water hydrology (May 2010). These studies resulted in three aspects: to evaluate the effect of aquatic herbivores on mature community of periphyton, in situ, and answered the hypothesis that the presence of herbivores alters community structure of periphytic algae, reducing their biomass, richness and density. In the other approaches as main result the effect of zooplankton and two herbivorous fish (Serrapinnus notomelas Eigenmann 1915 and Psellogrammus kennedyi Eigenmann 1903), the structure and dynamics of the periphyton community in microcosm experiment. It was also considered the effect of aquatic herbivores on chlorophyll-a and forms of dry weight of periphyton community. Furthermore, we observed the changes caused by different aquatic herbivores selected in the number, abundance and dynamics of taxa of periphyton community. Therefore, it was possible to record the aquatic herbivores modify the structure and dynamics of the periphyton community, promote the replacement of taxa and that the periphyton community responds to the aquatic herbivores.