Eficiência das áreas de conservação terrestres para a preservação da ictiofauna : o caso do Parque Estadual das Várzeas do Rio Ivinhema.

Abstract

The Parque Estadual das Várzeas do Rio Ivinhema was created in the high Paraná river floodplain due to high regional biodiversity, seeking to conserve this remnant floodplain that has fundamental importance in maintaining viable populations of fish species. The floodplain region consists of rivers and lagoons, and provides transitional periods of flood and drought, which are the bases for the reproduction of migratory species. The Ivinhema river (target) and Baía river (sentinel) were selected to assess whether the creation of the Parque Estadual das Várzeas do Rio Ivinhema was effective for the fish fauna conservation of the Paraná River remnant lotic stretch (between the Porto Primavera Dam and Itaipu Reservoir). Samples were collected during three different periods (1986 to 1988 - Period 1, 1992 to 1995 - Period 2, and 2000 to 2005 - Period 3). We evaluated the hydrological regime of rivers in the region, and metrics such as richness (number) of species abundance (proportion) of large migratory species and the similarities in the structure of fish assemblages. It was verified that species richness increased in the park and outside of this. The long-distance migratory species had decrease in their proportions over time, with lower values after the creation of the park. The similarities between the samples showed evidence of the benefit of the creation of the park in Period 3. Therefore, it was evident that the creation of the Parque Estadual das Várzeas do Rio Ivinhema had played its role for fish fauna conservation, especially for long-distance migratory species. However, the creation of conservation units in highly regulated rivers such as the Parana River, is only effective if the system's natural processes are also recovered, as the floods in this case.