Alimentação e assimilação energética de peixe herbívoro como indicadores de invasão em planície de inundação Neotropical.

Abstract

Diet composition, energy density (ED) and body condition factor (M̂i) are useful tools to identify the structure and functioning of the aquatic food chain, as well as the impacts on communities. Thus, about the hypothesis that the population of a herbivorous fish species presents lower variability of food items and, consequently, lower values in the physiological parameters (ED and M̂i) in the environment most impacted by the invasion of species, when compared to the populations of environments with less influence of invasive species, sampling was carried out on a Neotropical floodplain between 2015 and 2018. The composition and variability of food items, and ED, differed among subsystems, with the highest values recorded in the most impacted environment. The lowest values of M̂i were observed in the most impacted subsystem, and those considered less impacted did not differ. The greater variability of food items and energy density found in the impacted environment is due to the presence of invasive species, which occurred exclusively at this location. It is assumed that the lower values of M̂i are due to the energy expenditure of maintenance in the environment of greater transparency in the water column and associated with the escape of predation by the invader Cichla kelberi (Peacock bass), when compared with the investments in growth (lower standard length) and reproduction (lower population abundance). Therefore, it is suggested the implementation of management and monitoring measures that aim to control the presence of invasive species and ensure the maintenance of the biodiversity of native fauna.