The Upper Paraná river and its floodplain: main characteristics and perspectives for management and conservation

Abstract

In this chapter, we broadly described the floodplain, including geomorphological features, species richness, abiotic and functional aspects, regional and local impacts and finally, we concluded making suggestions to direct research and management of the area to guide its conservation. The last undammed stretch of the Paraná River and its remaining floodplain has two distinct surfaces: the Low Terrace and the Fluvial Plain. These create great habitat diversity in flooded areas where are included active and semi-active channels, lagoons, and elongated lowlands associated with paleochannels, and lowlands associated with the flood basin. Surveys conducted in the Upper Paraná River floodplain system since 1986, registered 2920 taxa of terrestrial and aquatic organisms. In the region, the flood pulse is still the main forcing function that regulates functioning and communities composition and structure. Main sources of impact on the area are the current process of human occupation that has to be disrupted and dams operation upstream from the area that has to be rationalized. Important steps to disrupt human occupation were the creation of three conservation units in the region and recently its incorporation into the Atlantic Forest Biosphere Reserve. Also, it is needed intense enforcement and, mainly, a wide program of environmental education (already started) to alert people, locals and visitors, about the importance of the area, its preservation and the main regional and local sources of impacts. Alterations in the hydrological regime by operation of upstream dams (27 major dams) seem to be the most important source of impacts on the river-floodplain system, especially after the closure of the Porto Primavera Dam. Even so, the area still plays fundamental role in the maintenance of the regional biodiversity of terrestrial and aquatic organisms. It is suggested to use dam operation as a tool to benefit local and regional biodiversity, simulating floods that are beneficial for most of the organisms. However, all these actions should be discussed in a basin Committee. This Committee, with ample representation of stakeholders, should guide and prioritize actions to be taken in the floodplain.