Dinâmica espaço-temporal do ictioplâncton no Alto Rio São Francisco

Abstract

Reproductive strategies are shaped by a set of physiological and ecological conditions, which vary according to species and environment. Through the techniques of sampling eggs and larvae and molecular analysis, this study aims to investigate and expand the information on the reproductive dynamics of fishes in the Upper São Francisco River. Six points were selected for ichthyoplankton and abiotic variables sampling: one point on the Samburá River (SAM), three points on the São Francisco River (before the confluence with the Samburá River - SFM; an intermediate point in Iguatama - SFI; and one point before the confluence with the Pará River - SFC), a point on the Bambuí River (BAM) and one on the Pará River (PARAC). Twenty four species of fish were identified, from eggs and larvae. Water transparency was the abiotic variable that most influenced ichthyoplankton densities, and in the largest number of locations. The point on the Pará River was the most different in ichthyoplankton composition, most likely due to the fact that it has four dams for hydroelectric generation in its main channel. The study confirms the importance of the Upper São Francisco for fish spawning and shows that species identification is essential to understand patterns of temporality and spatiality of fish reproductive events.