Partição da diversidade de zooplâncton ao longo da calha principal do Rio Parnaíba

Abstract

Large Rivers sustain a major portion of the aquatic biodiversity in the planet. The Parnaíba’s Basin, in this study is considery a large river. Is divided in to Upper, Medium and Low portions, which showed differences from each other, undergoing several biotic and abiotic influences. Thus, large Rivers promote good oportunities to study regulatory mechanisms of the natural distribution of the species because most of then have not been extensively altered. This study aimed to verify the partition of the zooplankton community diversity (rotifers, cladocerans and copepods), correlating it to different environmental variables along its course during the dry and rainy seasons along Parnaíba’s river. Nine sections were selected on the main channel of the Parnaíba’s river where one collection was performed at each season. The middle and lower portions of Parnaíba’s river showed up significantly more similar to each other than when they were compared with Alto Parnaíba’s portion. The environmental variables showed no significant variation along the sections, however, significant differences between seasons and portions were evident. Rotifers were the most abundant group, accounting for 85% of individuals in the dry and 51% during the rainy season. Cladocera contributed with 5% and 20%, respectively, and Copepoda, 10% and 29%, respectively. This high abundance of copepods is due to the large number of young forms of nauplii and copepodids found.