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

Alessandra Pasian Lonardoni,Taís Melo,Gislene Torrente-Vilara,Cristhiana Paula Röpke

doi:10.1590/1982-0224-2021-0087

Abstract

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

Highlights

Interspecific interactions are fundamental drivers of distribution patterns, local community assemblies, and evolutionary changes
This paper evaluated the species abundance, diet composition, dietary niche breadth, and diet overlap of congeneric (Acestrorhynchus falcirostris (Cuvier, 1819) and Acestrorhynchus heterolepis (Cope, 1878)) and non-congeneric (Hydrolycus scomberoides (Cuvier, 1819) and Rhaphiodon vulpinus Spix & Agassiz, 1829) piscivorous species before and after the construction of hydropower plant in the Amazon
We examined four piscivorous fishes: Acestrorhynchus falcirostris, A. heterolepis (Acestrorhynchidae), Hydrolycus scomberoides and Rhaphiodon vulpinus (Cynodontidae)

Summary

Introduction

Interspecific interactions are fundamental drivers of distribution patterns, local community assemblies, and evolutionary changes. Resource partitioning is an essential mechanism for species coexistence and population structure (Agostinho et al, 2003; Correa, Winemiller, 2014) that may arise from similar ecological requirements or facilitation interactions between species pairs (Robertson et al, 2014). Close species can share morphological attributes that allow them to explore similar resources. Because of this, they may experience stronger competition than phylogenetically distant species (Darwin, 1859; Webb et al, 2002). Interspecific competition can reduce niche breadth by evolutionary processes, resulting in intraspecific optimization (Polechová, Storch, 2018). The environment species skills offer a valuable role in resource partitioning and, the maintenance of competitive interactions depends on ecological stability and predictability (Cavin et al, 2013)

Methods

Results

Conclusion