Influência do Rio Negro e Solimões para a contribuição das fontes autotróficas de energia do Semaprochilodus insignis

Abstract

Semaprochilodus insignis is a detritivorous species that consumes of organic matter from plant and animal organisms. It forms large schools migrating between rivers of black and white waters, which were different concentrations of nutrients and sources of energy, the rivers Negro and Solimões. Investigating a contribution of the autotrophic sources of energy to the S. insignis of the lower Negro river and the lower Solimões river was the objective of this study. Carbon and nitrogen isotopic analyzes were performed on samples of fish muscle captured in the different environments. The isotopic values of the fish and the autotrophic energy sources used in the Stable isotope mixture model package in R (Simmr) for the determination of the estimates of the contributions of the sources. The results are isotopic indicating that S. insignis explores as autotrophic sources of energy in a differentiated way, according to the environment. In the low black river it explores the periphery (84%) as majority source. In the lower Solimões river it explores the bottom sediment in the floodplain, the detritus of terrestrial plants/macrophytes C3 (50%) and phytoplankton (42%). These results show that the food ecology of this species is unique, since it presents a variation in the autotrophic energy sources in quality and quantity, and that complement each other in different ambient. In this sense, maintaining the necessary conditions for the complete life cycle and consequently the natural stocks require a greater attention to involve two environments, in distinct and essential.