Foz do Rio Iguaçu como rota alternativa para a reprodução de peixes: jusante das cataratas do Iguaçu

Abstract

Abstract Dispersal patterns of early life stages of fish were evaluated in the Iguaçu River at Iguaçu National Park, Brazil-Argentina. Sampling was conducted in the stretch of 20 km, downstream the Iguaçu Falls to the mouth with Paraná River, over three spawning seasons (2011-2014). Higher densities of eggs drifting occurred especially in December, in 2012-2013. The eggs drift was high through all stretch, however, early stage of development was more abundant nearest downstream Iguaçu Falls, while later stages increased into the mouth. The larvae density drift was low, with predominance of preflexion and flexion stages, especially near the Iguaçu Falls. Our results revealed high drift of buoyant eggs highlighting fish spawning in the rapid and turbulent waters of the Iguaçu River, particularly downstream the Iguaçu Falls, and rainfall could be trigger to spawning. Eggs drift passively by rapid flow towards the mouth (5-11hours), probably most of them hatch in the Paraná River, and the larvae disperse to nursery habitats likely in Paraná River. Additionally, inshore zones along the stretch may provide habitats for the larval development