Food-resource partitioning among fish species from a first-order stream in northwestern Paraná, Brazil

Abstract

This study addressed the feeding ecology of fish fauna from a first-order stream located in a rural area. The purposes were to evaluate the influence of interspecific, seasonal and spatial factors on the diet, examine the dietary overlap, and determine the predominant food sources. Sampling was conducted in December 2007, September 2008, and March 2009, in three 50-m stretches of Itiz stream (upstream, intermediate, and downstream), through electrofishing. A total of 1,102 stomach contents were analyzed from 14 species, by the volumetric method. In general, allochthonous resources were predominant in the diets. Astyanax aff. fasciatus, Astyanax aff. paranae, Astyanax bockmanni, and Bryconamericus aff. iheringi consumed a higher proportion of plant remains, and Bryconamericus stramineus consumed predominantly Hymenoptera. The diets of Cetopsorhamdia iheringi, Characidium aff. zebra, Imparfinis schubarti, and Trichomycterus sp. consisted of aquatic insects, especially immature forms of Trichoptera, Ephemeroptera, Plecoptera, and Diptera. Hypostomus ancistroides, Hisonotus sp., Poecilia reticulata, and Rineloricaria aff. pentamaculata exploited mainly detritus, while Rhamdia quelen used a variety of items, predominantly terrestrial insects. Detrended Correspondence Analysis (DCA) showed a clear distinction among the species, with different morphology and feeding tactics. The Multi-Response Permutation Procedure (MRPP) supported this differentiation, and also indicated significant spatial and temporal variations in the dietary composition; the Indicator Value Method (IndVal) indicated the main items that contributed to these differences. The diet overlap among species was low (< 0.4) to around 78% of pairs, and the mean value did not vary significantly among the sites or between hydrological periods within each site. According to the null model of Pianka's index, the values for dietary overlap were significantly higher than expected at random, showing evidence of resource sharing. This was related to the availability of allochthonous resources, highlighting the importance of riparian vegetation as a source of these resources for maintaining the fish fauna of the stream.Este estudo abordou a ecologia alimentar da ictiofauna de um riacho de primeira ordem situado em área rural. Os objetivos foram verificar a influência dos fatores interespecíficos, sazonais e espaciais sobre a dieta, avaliar a sobreposição alimentar, além de determinar os recursos alimentares predominantes. As amostragens foram realizadas em dezembro/2007, setembro/ 2008 e março/2009, em três pontos do riacho Itiz (montante, intermediário e foz) com extensões de 50 m, através de pesca elétrica. Foram analisados 1102 conteúdos estomacais referentes a 14 espécies de acordo com o método volumétrico. De forma geral observou-se que a maior contribuição na dieta das espécies foi de recursos alóctones. Astyanax aff. fasciatus, Astyanax aff. paranae, Astyanax bockmanni, Bryconamericus aff. iheringi, consumiram maior proporção de vegetal e Bryconamericus stram...

Ecomorphology and diet reflect the spatial segregation between two Siluriformes species inhabiting a stream of the Bodoquena Plateau, in Central Brazil

“…schubarti. However, other studies focusing on other species of Imparfi nis, as well as I. schubarti, have confi rmed the results reported here (Ferreira & CasaTTi, 2006;silva et al, 2012). In contrast to the patterns observed for P. taenioptera, the less variable and strictly insectivorous diet exhibited by the studied riffle-dwelling species corroborates previous findings that have highlighted the dominance of insectivorous species with more specialized habitats in riffles (CasaTTi & CasTro, 1998;Teresa & CasaTTi, 2012).…”

Diet and ecomorphological relationships of an endemic, species-poor fish assemblage in a stream in the Iguaçu National Park

“…Despite the low richness (seven species), the trophic structure is comparable to other tropical fish assemblages, for which higher species richness does not necessarily imply the existence of considerable differences in the composition of the food items (Esteves & Lobón-Cerviá, 2001;Silva et al, 2012).…”

Importance of allochthonous resources in the diet ofAstyanax aff. fasciatus (Osteichthyes: Characidae) in streams: a longitudinal approach

“…fasciatus consumed a wide range of food items and there was a predominance of allochthonous resources in the diet, particularly insects and plants, along the longitudinal gradient. Several studies in streams, involving the diet of fish fauna, reveal the importance of allochthonous subsidies to many species (Esteves & Aranha 1999, Lowe-McConnell 1999, Casatti 2002, Silva et al 2012, especially for the genus Astyanax , Borba et al 2008, Wolff et al 2009, Ferreira et al 2011, Ferreira et al 2012, Manna et al 2012. Specifically for A. aff.…”

“…The headwaters region is influenced by the surrounding vegetation, which contributes with allochthonous material (plant material and terrestrial insects), as the stream enlarges, decreases the importance of importing terrestrial organic matter. The riparian vegetation is well documented in the literature as a major supplier of food for aquatic organisms (Vannote et al 1980, Polis et al 1997, Baxter et al 2005, Manna et al 2012, Silva et al 2012, in turn controlling the flow of nutrients. The shading produced by riparian vegetation limits the autotrophic production, and fish depend on resources from the slopes for feeding (Lowe-McConnell 1999).…”