Distribuição e alimentação de duas espécies simpátricas de piranhas Serrasalmus maculatus e Pygocentrus nattereri (Characidae, Serrasalminae) do rio Ibicuí, Rio Grande do Sul, Brasil

Abstract

ABSTRACT. Distribution and feeding of two sympatric species of piranhas Serrasalmus maculatus and Pygocentrus nattereri (Characidae, Serrasalminae) of the Ibicuí river, State of Rio Grande do Sul, Brazil. Two species of piranhas occur in the Ibicuí River, one of the main tributaries of the Uruguay River in southern Brazil, Serrasalmus maculatus Kner, 1858 and Pygocentrus nattereri Kner, 1858. In order to analyze the distribution and feeding habits of these species we conducted collecting expeditions from December 1999 to January 2002, using a variety of fishing gears in three sites along the river, both in lentic and lotic habitats. A total of 203 individuals of S. maculatus and 86 of P. nattereri were caught, mostly in lentic habitats and closer to the Uruguay River, were P. nattereri seems to be more concentrated. The number of individuals captured at different times did not show variation in P. nattereri while the number of S. maculatus captured at mid-night was the highest. Young S. maculatus (2-4 cm standard length) fed mainly on fish fins and insects. Fish was the predominant item in remaining size classes for both species, with intra-and inter-specific overlap in larger classes (8-16 cm and >16 cm standard length). No differences in the repletion index between day time or habitats, were observed for the two species.

Trophic ecology of two piranha species, Pygocentrus nattereri and Serrasalmus marginatus (Characiformes, Characidae), in the floodplain of the Negro River, Pantanal

“…The ingestion of fragments or whole individuals of insect, was also described by Sazima and Machado (1990); Resende et al (1996); Behr and Signor (2008); Agostinho et al (2003). They attest that the insects intake and other invertebrates in the diet of carnivorous fish is associated to the place and the time of the year and because of that, piranha species, as many of the tropical and subtropical fish species, may be considered polyphagous, ie, they feed on diverse and available food, as insects, microcrustaceans and shrimps.…”

“…In spite of being piscivorous predators, plants were also registered in a great volumetric frequency of stomachs, as well as in studies of Nico and Taphorn Trindade and Jucá-Chagas (2008). Some authors reported that the intake of higher aquatic plants by piranhas is related to accidental intake during the predatory act (Machado-Allison and Garcia, 1986;Costa et al, 2005;Piorski et al, 2005;Behr and Signor, 2008). Similarly, Carvalho et al (2007) in Pantanal wetland, attested that the predatory tactic employed by P. nattereri and S. maculatus, which consists of taking small bites of fish or other items on the water surface among aquatic macrophytes, may result in a high frequency of plant matter in the stomachs.…”

Parasitism by argulids (Crustacea: Branchiura) in piranhas (Osteichthyes: Serrasalmidae) captured in the Caiçara bays, upper Paraguay River, Pantanal, Mato Grosso state, Brazil

“…The authors registered P. nattereri swimming in schools of 20 to 30 individuals and S. spilopleura (= Serrasalmus maculatus in Paraguay River) in schools of up to 20 fish (Sazima & Machado, 1990). Pygocentrus nattereri and S. spilopleura (= Serrasalmus maculatus in Paraguay River) are sympatric species (Behr & Signor, 2008). The gregarious or solitary behaviors were the main factors determining the structure of the parasites infra-communities in S. spilopleura (= Serrasalmus maculatus in Paraguay River), a gregarious species, and S. marginatus, a non-gregarious species (Tanaka, 2000).…”

Feeding ecology of Serrasalmus gouldingi (Characiformes: Serrasalmidae) in the lower Anapu River region, Eastern Amazon, Brazil

“…According to literature, the consumption of fruits or seeds may occur accidentally, or in response to their availability for a specific period, or even as a strategy to maximize energetic gain during flood seasons (Behr and Signor 2008;Correa and Winemiller 2014). However, little information is available on the feeding behavior of Serrasalmus, hampering any conclusive understanding of processes that lead to the ingestion of these items as well as their importance in the diet of this species (Sazima and Machado 1990).…”