Feeding ecology of three Astyanax species (Characidae, Tetragonopterinae) from a floodplain lake of Mogi-Gua�� River, Paran� River Basin, Brazil

Abstract

SynopsisThe feeding ecology of three characids ( A . fasciatus, A. bimaculatus and A. schubarti) was studied monthly during 1988 in Lake Inferngo, a major floodplain lake of the Mogi-Guaqu River in the State of SBo Paulo. River flooding directly influenced the diet of the omnivorous A. bimaculatus and A. fasciatus which responded to maximum inundation (March) by consuming predominantly allochthonous insects. In contrast, A. schubarti was less influenced by the river flood cycle on qualitative changes in diet and relied basically on aquatic macrophytes and periphytic algae. The importance of zooplankton in the diet of the three species was low, and may be attributed to its low density in the water column (< 1 ind 1.'). Ontogenetic diet changes were evident for the three species. For A. fasciatus and A. birnaculatus the importance of zooplankton was high at the early stages, decreasing with size. A. schubarti at younger stages consumed diversified items which gradually decreased quantitatively up to the size class of 65 mm; from this size onwards, the diet became restricted to the consumption of periphytic algae and macrophytes.

The opportunistic feeding and reproduction strategies of the annual fish Cynopoecilus melanotaenia (Cyprinodontiformes: Rivulidae) inhabiting ephemeral habitats on southern Brazil

“…Ephemeral environments with a high density of macrophytes, such as the wetland under study, are inhabited by multiple species of small fishes. Possible explanations for the preference of these habitats by small fishes are that they offer shelter, protection from predators and a high availability of food resources like insect larvae and small crustaceans (Junk et al, 1989;Esteves & Galetti Jr., 1995;Esteves, 1996;Winemiller & Jepsen, 1998;Motta & Uieda, 2005). Other studies also reported the occurrence of C. melanotaenia with non-annual fishes (VazFerreira et al, 1966;Quintela et al, 2007) and, probably, the coexistence of different species in transient pools may be due to connection of water bodies during rainfall events (Errea & Danulat, 2001).…”

Astyanax paranae Eigenmann, 1914 (Characiformes: Characidae) in the Alagados Reservoir, Paraná, Brazil: diet composition and variation

“…However, the expressive consumption of detritus/sediment in Alagados Reservoir was particularly intriguing, because of the unusual presence of this food resource as the main item in the diet of Astyanax species. In spite of their trophic opportunism, these characids have been related in literature as omnivorous, herbivorous, insectivorous and zooplanktivorous (Arcifa et al, 1991;Meschiatti, 1995;Esteves, 1996;Agostinho et al, 1997;Castro & Casatti, 1997;Bennemann et al, 2000;Cassemiro et al, 2002;Vilella et al, 2002).…”

Aspectos da história natural de Astyanax scabripinnis Jenyns (Teleostei, Characidae) em um riacho de floresta com araucária no sul do Brasil

“…Muito embora o comportamento das espécies aquáticas frente aos fatores físicos e químicos deste ambiente ainda não seja conhecido, é provável que, como já descrito para áreas naturalmente alagáveis, a flutuação nos fatores ambientais durante as inundações da floresta de galeria exerça grande influência sobre a disponibilidade de alimento e abrigo para a fauna aquá-tica (ESTEVES 1996, HARPER et al 1997.…”