Diet and dietary overlap of three sympatric fish species in lakes of the upper Paraná River floodplain

Abstract

For a dietary study, specimens of Astyanax bimaculatus, Astyanax schubarti, and Moenkhausia intermedia were caught monthly with seines-nets in six lakes (Pau Veio, Porto Rico, Três Amigos, Mutum, Pontal, and Canal do Meio), on the floodplain of the Upper Paraná River, from March 1992 through February 1993. We analyzed stomach contents of 599 A. bimaculatus, 293 A. schubarti, and 394 M. intermedia, by the Occurrence and Points methods, combined in the Alimentary Index (AI). This analysis revealed that these species have broad dietary spectra. A. bimaculatus was an omnivore, with a tendency toward herbivory-insectivory. In most of the lakes it consumed terrestrial insects, followed by higher plants and microcrustaceans. A. schubarti was an omnivore, consuming the same type of items in the different lakes, in different proportions depending on the locality. M. intermedia was a planktophage, feeding mainly on cladocerans (more than 50%) in all the lakes except for Pontal, where higher plants were predominant (45.1%). Although A. bimaculatus and A. schubarti consumed similar items in the different localities, detrended correspondence analysis (DCA) showed distinct segregation among the three species in all lakes studied.<br>Para estudo da dieta foram capturados mensalmente exemplares de Astyanax bimaculatus, Astyanax schubarti e Moenkhausia intermedia com redes de arraste, em seis lagoas (Pau Velho, Porto Rico, Três Amigos, Mutum, Pontal e Canal do Meio), na planície de inundação do alto rio Paraná, de março/92 a fevereiro/93. Foram analisados 599 conteúdos gástricos de A. bimaculatus, 293 de A. schubarti e 394 de M. intermedia, pelos métodos de Ocorrência e Pontos, combinados no Índice Alimentar (IAi). Tal análise revelou que estas espécies apresentam amplo espectro alimentar. A. bimaculatus foi caracterizada como onívora com tendência a herbivoria-insetivoria, consumindo, na maioria das lagoas, insetos terrestres, seguidos de vegetal superior e microcrustáceos. A. schubarti foi caracterizada como onívora, consumindo os mesmos tipos de itens nas diferentes lagoas, com proporções distintas, dependendo do local. M. intermedia foi caracterizada como planctófaga, alimentando-se principalmente de Cladocera (mais de 50%) em todas as lagoas, exceto na Pontal, onde vegetal superior se sobressaiu (com 45,1%). Embora A. bimaculatus e A. schubarti tenham consumido itens semelhantes nos diferentes locais, a análise de correspondência destendenciada (DCA) evidencia uma nítida segregação entre as três espécies em todas as lagoas estudadas

Spatial, seasonal and ontogenetic variation in the diet of Astyanax aff. fasciatus (Ostariophysi: Characidae) in an Atlantic Forest river, Southern Brazil

“…as well as spatial and seasonal modifications in the composition of its diet. This was observed in other characin species (Luz & Okada, 1999;Mazzoni & Rezende, 2003).…”

Molecular data reveal a diverse Astyanax species complex in the upper Iguaçu River

“…Several authors have indicated considerable ecological diversity in A. altiparanae , both in diet (Luz & Okada, 1999) and behaviour (Suzuki & Orsi, 2008). The deep divergence observed among sympatric haplotypes, however, indicates that two biological species might be currently recognized by the same name, which could partially explain its ecological versatility.…”

Biotic resistance by snails and fish to an exotic invasive aquatic plant

“…To better understand the role of the simultaneous biological interactions that affect the early establishment phase of H. verticillata invasions, we conducted a mesocosm experiment that assessed the individual and combined effects of three aquatic species that damage H. verticillata in different ways and represent some of the possible biotic interactions found in lakes. Based on our prior observations (see also Langeland, 1996;Luz & Okada, 1999;Fellerhoff, 2002 (Sousa, 2011), probably from a single introduction of a dioecious female (Sousa, 2011). Despite the high degree of phenotypic plasticity in H. verticillata, the plant has not been able to establish stable populations in floodplain lakes (Sousa, 2011;Sousa et al, 2009), which are inhabited by the resistance-promoting species that we considered in this study (M. forestii, Pomacea spp.…”

“…Based on our prior observations (see also Langeland, 1996;Luz & Okada, 1999;Fellerhoff, 2002 (Sousa, 2011), probably from a single introduction of a dioecious female (Sousa, 2011). Based on our prior observations (see also Langeland, 1996;Luz & Okada, 1999;Fellerhoff, 2002 (Sousa, 2011), probably from a single introduction of a dioecious female (Sousa, 2011).…”