Diferentes abordagens no estudo da ecologia de peixes em uma cascata de reservatórios

Abstract

The main hydrographic basins in Brazil are currently under the influence of dams from hydroelectric projects. The existence of a cascade of reservoirs can accentuate all types of impacts caused by the damming. In the case of fish, it is expected that, over time and space, the effect of reservoir cascades will be more pronounced from one reservoir to another. Here, we evaluated the diet of a non-native species, through analysis of stomach contents, and the fish size distribution, through hydroacoustics, over time and space in a cascade of reservoirs’ system. We saw that the diet of Knodus moenkhausii was influenced by the region in which it is found and, although the relationship with the abundance of food items was only marginally significant, the most abundant items also presented higher values of frequency of occurrence in the stomachs. With hydroacoustics, we saw that the largest fish are found in the most lotic or closest to lotic portions of the system, both in the Dry and Rainy seasons. Between seasons, we saw that the size of fish is greater in Rainy season in most regions and there is movement of fish, which is probably related to migratory species’ necessity to move upstream toward the lotic streches in the Rainy season.