Ecosystems

Abstract

The Paraná River is characterized by a high spatial and temporal heterogeneity that includes a wide variety of permanent and temporary ecosystems regulated by the hydro-sedimentological regime and hydrological connectivity. • The longitudinal and lateral connectivity between rivers and floodplains is vital to maintain the functionality of ecosystems within the basin and to maintain its high biodiversity. Development by man threatens the connectivity between aquatic environments, posing a risk to biodiversity. • In the basin of the Paraná River there are several large wetlands, currently characterized by minimal intervention by man, except in the stretch of Upper Paraná, where there are many hydroelectric dams and reservoirs. Unlike many other great river systems around the world, the headwaters of the Paraná River are located in a tropical region and the river passes in a southerly direction through subtropical and then temperate regions, which contributes to changes in biotic diversity from north to south. • The high biodiversity includes faunal groupings from benthic invertebrates and zooplankton to mammals, and the aquatic plants are essential components of the flora, providing refuge and food for the fauna. • The complexity of the system, together with the lack of effort by the countries within the basin to investigate the species diversity has contributed to uncertainty regarding the conservation status and risks to biodiversity. Therefore, many species are identified as having Data Deficient (DD) status in the IUCN Red List.