Damming in the Madeira River modifies the food spectrum of piscivorous and affects their resource partitioning

Abstract Phylogenetic proximity suggests some degree of diet similarity among species. Usually, studies show that species coexistence is allowed by partitioning food resources. We evaluate how visually oriented piscivorous fishes (Characiformes) share prey before and after building the Santo Antônio Hydroelectric Power Plant (HPP) in Madeira River (Brazil), largest muddy-water tributary Amazon River. Piscivorous (Acestrorhynchus falcirostris, Acestrorhynchus heterolepis, Hydrolycus scomberoides, Rhaphiodon vulpinus) were sampled under pristine (pre-HPP) disturbed (post-HPP) environmental conditions. analyzed abundance stomach contents for fullness composition to check variations between congeneric non-congeneric The percent volume taxa was normalized grouped into taxonomic family level determine diet, niche breadth, overlap. Only R. vulpinus increased post-HPP. There no significant variation breadth periods, while overlap decreased Our results indicate river impoundment affected distinct ways modified their resource partitioning. Therefore, interspecific interactions a required tool understand respond damming.