Feeding ecology of Pachyurus bonariensis Steindachner, 1879 (Sciaenidae: Perciformes) in the Ibicuí River, Southern Brazil: ontogenetic, seasonal and spatial variations

Abstract

Knowledge of the feeding ecology of fish is essential for understanding the functioning of freshwater communities. Here we report on an analysis of the diet of Pachyurus bonariensis Steindachner, 1879, a freshwater sciaenid. Fish were collected bimonthly from December 1999 to January 2002 at three locations along the Ibicuí River in the Rio Grande do Sul State, Brazil. At each location, the specimens were collected in both lentic and lotic environments. The stomachs of 324 fish were analysed for contents and fullness. The main items were Ephemeroptera, Diptera (larvae), Trichoptera and Odonata. Annelida, plant matter, Decapoda, Diptera (pupae), Coleoptera and Mollusca were present in small amounts. The fish consumed smaller amounts of food in winter than in other seasons. The most important source of dietary variation for P. bonariensis was the ontogenetic, related to intrinsic biological characters. However, spatial variation was also found, suggesting that this species can adapt its diet to environmental changes. Although P. bonariensis showed ontogenetic and spatial variations in the main items consumed, the main items were always insects, characterising P. bonariensis as a fish with an insectivorous feeding habit in the Ibicuí River.Keywords: feeding activity, diet composition, trophic ecology, insects, fishes. Biol., 2010, vol. 70, no. 3, p. 503-509 the dominant species (Behr, 2005). For this, the dietary composition and the feeding activity were studied, and its ontogenetic, seasonal and spatial variations. The dietary composition was analysed to investigate, in Ibicuí River, its insectivorous specialised diet (Fugi et al., 2007). The ontogenetic, seasonal and spatial variations in trophic spectrum were also investigated to confirm its specialised diet at different situations and to analyse what is the mainly source of dietary variations, those principally due to food availability, seasonal and spatial, or the ontogenetic variation. Its feeding activity was analysed to investigate the influence of year seasons and spatial heterogeneity on food ingestion. Ecologia trófica de Pachyurus bonariensis

Feeding patterns, trophic structure and damming rivers effect: studies applied in freshwater environments in the Brazilian semi-arid region

“…The description of the food items consumed by all fish species in a community is the starting point for the recognition of a natural trophic structure (Mazzoni et al 2010). It is necessary to know the trophic spectrum and the food activity of the species in their environment to achieve success in conservation efforts (Lima and Behr 2010).…”

Trophic ecology of Hemigrammus marginatus Ellis, 1911 (Characiformes, Characidae) in a conserved tropical stream

“…Young individuals of the first standard length class consumed a large amount of zooplankton. The ontogenetic variations in freshwater fish diet have been commonly reported in the literature (Hahn et al, 2000;Lima-Junior and Goitein, 2003;Cassemiro et al 2008;Mazzoni and Costa, 2007;Agostinho et al, 2009;Suiberto et al, 2009;Abilhoa et al, 2010;Lima and Behr, 2010;Mazzoni et al, 2010;Bonato and Fialho, 2014). The ontogenetic variations found in the H. marginatus diet in the Beija-Flor stream are determined by the size of the fish, prey and ease of predation of available food resources, as the fish become adults, predation by the zooplankton item undergoes a significant decrease.…”

Feeding ecology of Dash-dot Tetra Hemigrammus belottii(Steindachner 1882) (Characiformes: Characidae) in the streams of the Urucu River basin, central Amazonia, Brazil

“…While a number of studies have recorded spatial and temporal variation in fish diets (Hahn et al 1992, Motta & Uieda 2004, Brandão-Gonçalves et al 2009, Lima & Behr 2010, no such pattern was recorded in H. belottii, probably related to the generalist behavior of the species, which appears to be typical of the characids (Bennemann et al 2005, Silva et al 2008, Brandão-Gonçalves et al 2009). However, the lack of variation may also be related to the abundance of resources in Amazonian streams (Knöopel 1970).…”

“…The fish fauna of the Neotropics is dominated by relatively unspecialized opportunist species, which feed on a wide variety of resources, the availability and abundance of which may vary considerably over time and through space, associated with fluctuations in physical-chemical variables and the productivity of the environment (Lowe-McConnell 1999, Lima & Behr 2010. However, Knöopel (1970) found no seasonal variation in the composition of the diets of fishes in Amazonian streams, and attributed this finding to the availability of feeding resources in this environment, as well as the pronounced spatial stratification related to the availability of a wide range of different microhabitats, which was corroborated by other authors (Wootton 1992, Anjos 2005.…”