Abundance of planktonic and non-planktonic rotifers in lagoons of the Upper Parana River floodplain

The aim of this study was to analyse the planktonic and non-planktonic rotifers density in the pelagic region of several lagoons on the floodplain of the Upper Parana River, during two distinct hydrological periods. In the dry period the total density of planktonic species was greater than the density of the non-planktonic species. The difference was significant. On the other hand, in the flood period the non planktonic species were more abundant, but the difference was not significant. Planktonic species contributed with 87.46% in the abundance in the lagoons associated to Ivinheima river and 90.65% in the Baia river lagoons. During the flood period non-planktonic species contributed with 61.68% of the total density in the Ivinheima River lagoons and 66.39% in the Baia river lagoons. ANOVA shows a significant relationship between the type of river (with more sediments suspended or not), the hydrological period and the variation of total density of planktonic and non-planktonic species. Based on these result was possible to verify the effect of changes in water level and the peculiar characteristics of the lagoons on the structure and dynamics of the planktonic and non-planktonic rotifers.