Biodiversity, structure of the communities and ecological processes in a river/lake ecotone zone: a study in the mouth region of the Paranapanema River into the Jurumirim Reservoir

Abstract

The mouth zone of a river into a reservoir forms an ecotone . This ecological unity is a transition region between two adjacent ecosystems and presents some peculiarities from the adjacent environments. In the ecotone study, the structural and functional compounds must to be determined and described. The ecotones present different morphology and anatomy; they are differentiated by a typical composition(specific richness and diversity) and by a temporal dynamics related to abiotic factors. In river/reservoir zone, two types of ecotone can be found: the longitunal and the lateral ecotones. In the first, a significant decrease on the water velocity and a deposition of the material transported by the river are observed, while the second type of ecotone, is shaped by the riparian regions and /or by the inundation areas where the land topography is suitable and hydrological pulses of water produce a flood in the lateral zones. This project intend to describe, for the mouth zone of the Paranapanema River into the Jurumirim Reservoir: a) the structure and the shape of the lateral and longitudinal ecotones, with an emphasis on its sinuosity grade and on its resolution pattern of the macrophyte band ; b) the temporal dynamics of the morphology of these transition zones; c) the functional role of the ecotone zones, as habitat and conduit, filter or barrier, source or sink of organic matter and chemical elements ; d) the biological diversity (macrophytes and the associated fauna, constituted by plankton and fishes), its temporal modifications and its interactions with abiotic factors ; e) the dynamics of macrophyte decomposition; the contribution to degradation of organic matter and the nutrient release to the aquatic ecosystem ; f) the alimentary diet of some dominant fish species having an economic importance in this transition zone, in order to show the trophic structure of the ecotonal communities; g) the distribution pattern of some exotic fish species introduced from other drainage basins and its impact and adaptation in the communities of the ecotone regions; h) the cytogenetic determination of some species from the Characiform, Silurifonn and Perciform Orders, to evaluate the genetic biodiversity of this fish community; i) the cariotypic characteristics of some species of the Anastomidae Family to determine its taxonomic and systematic position and also to show some probable intrapopulation differences of the Prochilodus scrofa species. (AU)