Abstract
The composition of the diet of two species of characids (Knodus heteresthes and Moenkhausia lepidura) was evaluated in the Teles Pires and Juruena Rivers, sampled in September and October 2016. We analyzed 226 stomachs of K. heteresthes and 425 of M. lepidura. The analysis of the stomach contents was based on volumetric and frequency of occurrence methods, applying the food importance index. For the similarity of the diets between the species we calculated the niche overlap with Pianka's index. Both species in the Juruena River have a dietary preference for arthropods (IAi > 0.95). In the Teles Pires River the diet is concentrated in three sources for both species: arthropods (IAi > 0.52), vegetables (IAi > 0.33) and fish (IAi > 0.12). The diet was dissimilar when compared to environments (ANOSIM, R ≥ 0.57, p < 0.001) with high trophic niche overlap (α > 0.97), regardless of the sampled environment. In the Teles Pires River, both species were classified as omnivorous with an insectivorous tendency and in the Juruena River the insectivorous behaviour occurs.
Highlights
Neotropical freshwater fish represent one-eighth of all vertebrate biodiversity and approximately one-fourth of that of the globe fish species (Vari and Malabarba, 1998), and among them, the Family Characidae (Characiformes) is the most diverse freshwater fish, with among 1600 described species (Lévêque et al, 2008), distributed along the South, Central and North America and Africa
One hundred individuals of K. heteresthes were collected in the Juruena River and 126 in the Teles Pires River, and for M. lepidura 177 were collected in the Juruena River and 248 in the Teles Pires River
For the Juruena River, 23 food items were found for K. heteresthes and 19 for M. lepidura
Summary
Neotropical freshwater fish represent one-eighth of all vertebrate biodiversity and approximately one-fourth of that of the globe fish species (Vari and Malabarba, 1998), and among them, the Family Characidae (Characiformes) is the most diverse freshwater fish, with among 1600 described species (Lévêque et al, 2008), distributed along the South, Central and North America and Africa. Due to the huge diversity of species, morphological similarities and feeding habit, coexistence between some species of Characidae is still poorly understood in aquatic environments (Mol, 1995), while the segregation seems to. Pianka (1974) points that two species can coexist only if they differ in at least one niche (trophic, spatial or temporal). Specziár and Erős (2014) suggest that the trophic segregation in aquatic environments can be more significant than habitat sharing or seasonality in the process of coexistence. In this perspective, studies focused on fish dietary can provide significant informations about community structure and habitat structure that can be useful in conservation programs (Barletta et al, 2010)
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