Influência do ciclo hidrológico, maturação gonadal e categoria trófica no teor energético de peixes em uma área de várzea da Amazônia Central

Abstract

The influence of hydrological cycle, gonad development and trophic level on the energy allocation was investigated considering five fish species from an Amazonian floodplain area, Catalão. Sampling was carried out monthly using gillnets of different mesh sizes for 24 hours. Body fat index, gonadossomatic index, condition and energy density from muscles, gonads and stomach content of five species were analyzed. Amongst the various trophic groups considered, the piscivours Acestrorhynchus falcirostris and Pygocentrus nattereri showed the lowest level of caloric content in the muscle, high numbers of empty stomachs throughout the sampling period and very high levels of energy density in their food, which allows them to take food less frequently. On the other hand the invertivores species Hemiodus sp and Hoplosternum littorale and the herbivore Rhytiodus microlepis, in order to compensate their low energy diet, need to take food very frequently. In order to guarantee gonad development, Acestrorhynchus falcirostris use body fat whereas Pygocentrus nattereri use energy from muscle and Hoplosternum littorale uses energy from both places. The sedentary species Acestrorhynchus falcirostris and Hoplosternum littorale showed the same energy allocation pattern as the migratory ones, which is strongly related to the flood pulse. It is quite clear that the flood pulse regulates the gain and utilization of the energy reserves in aquatic organisms from the Amazonian floodplain.