Aquatic insects as the main food resource of fish the community in a Neotropical reservoir

Ana Paula Vidotto-Magnoni,Edmir Daniel Carvalho

doi:10.1590/s1679-62252009000400020

Ana Paula Vidotto-Magnoni, Edmir Daniel Carvalho

Open Access

https://doi.org/10.1590/s1679-62252009000400020

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Abstract

We evaluated the feeding of fish species of the Nova Avanhandava Reservoir, low Tietê River, São Paulo State, Brazil. Fishes were collected in two stretches of the reservoir: Santa Bárbara (14 samples) and Bonito (two samples) between September 2002 and March 2004, using gill and seining nets. The results of stomach contents analysis were expressed with the frequency of occurrence and gravimetric method, combined in the Alimentary Index (AI). The 20 species studied consumed 52 food items, grouped in 10 food categories: aquatic insects, terrestrial insects, crustaceans, fish, macroinvertebrates, microcrustaceans, algae, vegetal matter, detritus/sediment and scales. The aquatic insects (mainly Chironomidae, Odonata and Ephemeroptera) were the most common food resources, consumed by 18 species. The diet composition of the community (species grouped) indicated that the dominant food category in the diet of fishes was aquatic insects (AI = 77.6%), followed by crustaceans (AI = 7.1%). Four trophic guilds were identified according a cluster analysis (Pearson distance): insectivorous (10 species), omnivorous (4 species), detritivorous (3 species) and piscivorous/carcinophagous (3 species). Despite the highest number of species, the insectivorous guild was responsible for more than 80% in captures in number and biomass (CPUEn and CPUEb). The low values of niche breadth presented by all species, along with the low values of diet overlap between species pairs indicate a high degree of food resources partitioning among species. The aquatic insects, despite being the main food resource of insectivorous fishes, also complemented the diet of other species, which demonstrate the importance of this food resource for the fish community, sustaining a high diversity, abundance and biomass of fishes.

Highlights

Studies of trophic structure and resource partitioning of fish assemblages are important for the understanding of ecological relationships among fish species and with other aquatic organisms, which can support management of natural populations (Agostinho et al, 1995; Woodward & Hildrew, 2002)
Some can present a high abundance of piscivorous fishes, especially in the first years of closure of reservoirs, since there is a high abundance of prey (Mérona et al, 2001, 2003)
The main food resources consumed by the fish fauna are originated in the aquatic system, such as aquatic insects, other invertebrates, zooplankton, detritus and fish (Agostinho et al, 2007), sustaining a great diversity and abundance of fishes (Araújo-Lima et al, 1995)

Summary

Introduction

Studies of trophic structure and resource partitioning of fish assemblages are important for the understanding of ecological relationships among fish species and with other aquatic organisms, which can support management of natural populations (Agostinho et al, 1995; Woodward & Hildrew, 2002). Several groups are abundant in Neotropical reservoirs, especially dipterans of the family Chironomidae, ephemeropterans and odonats (Higuti et al, 2005; Hahn & Fugi, 2007). These organisms have an important role in the metabolism of aquatic systems (Pereira & De Luca, 2003), and as food resource for fishes in streams (Pouilly et al, 2006; Pinto & Uieda, 2007) and higher order rivers (Horeau et al, 1998). They are significant food resource for fishes in reservoirs (Arcifa & Meschiatti, 1993; Callisto et al, 2002; Luz-Agostinho et al, 2006)

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