A ictiofauna de áreas rasas do complexo estuarino baía de Paranaguá, Paraná

Abstract

The present work investigated the ichthyofauna in the shallow waters of the Paranaguá Bay estuarine complex, Paraná state, Brazil, considering eight sample sites along the north-south axis. The analyses of the physical and the chemical data series of the water and the biological data monthly obtained, taking in account the sediment data series seasonally determined in each site, making possible the environmental characterization and the quali-quantitative assessment of the local ichthyofauna. The hydrological parameter values reflecting an environmental gradient defined by the increasing from the north to the south region of the estuary. The northern sample sites were characterized by higher continental water influence, lower hydrodynamic and higher fine granules amount in the sediment. The biological data analyses of the ichthyofauna in the studied area showed that the complete life cycles of some species take place in this area, emphasized by the relevant occurrence frequencies of juvenile and adult specimens. In the meantime, the highest values of the hydrological parameters were registered on the southern sample sites of the estuary, showing the influence of the marine salt water and characterized by the higher hydrodynamic forces reflected by the high amount of thick granules in the sediment. The ichthyofauna is mainly represented by juvenile fish of marine species that utilize the estuary in some periods of the year and by sporadic marine species. The shallow water ichthyofauna of the Paranaguá Bay estuarine complex is composed by 96 species with predominance of occasional species in comparison to the constant ones, indicating a dynamic environment. The quantitative data analyses of the ichthyofauna showed seasonal differences as in the species composition as in the catch proportion, resulting in a seasonal characterization of the specific richness, of the species diversity, of the eveness and of the similarity indices. The results of the present study emphasize the spatial-temporal heterogeneity of the environment, taking in account its characteristics and the ichthyofauna composition, revealing that the shallow waters of Paranaguá Bay estuarine complex constitute a highly dynamic environment.