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

Abstract

Aspects of the feeding ecology of a small characin, Astyanax paranae, were studied during 1996/1997 and 1998/1999 in the Alagados Reservoir, Paraná, Brazil (25º01'50.0'' S; 050º03'41.9'' W). Fishes were quarterly captured from the reservoir's riverine and lacustrine zones and stomachs contents of 711 adult individuals were analyzed by volumetric method. Species' feeding spectrum and spatial, temporal and sexual variations on diet were evaluated. Data matrix was summarized by detrented correspondence analysis (DCA) and the axes scores from DCA were used as variables in one-way ANOVA of null models to test diet variations. Astyanax paranae fed on detritus/sediment, plant matter, algae and aquatic and terrestrial invertebrates. The timespace prevalence of detritus/sediment and plant matter on diet characterized the feeding habit as detritivorous tending to herbivory. Significant differences on food items proportions occurred between the sampling months and sampling sites and were related to resources availability, characterizing the species trophic opportunism.Aspectos da ecologia alimentar de um pequeno caracídeo, Astyanax paranae, foram estudados durante 1996/1997 e 1998/1999 no reservatório de Alagados, Paraná, Brasil (25º01'50,0'' S; 50º03'41,9'' W). Os peixes foram capturados trimestralmente nas zonas fluvial e lacustre do reservatório e os conteúdos gástricos de 711 espécimes adultos foram analisados através do método volumétrico. Foram avaliados o espectro alimentar da espécie e alterações espaciais, temporais e entre os sexos na dieta. A matriz de dados foi sumarizada através da análise de correspondência com remoção do efeito do arco (DCA) e os escores dos eixos resultantes da DCA utilizados como variáveis em análises de variância (ANOVA) unifatoriais de modelos nulos para testar diferenças na dieta. Astyanax paranae consumiu detrito/sedimento, vegetais, algas e invertebrados aquáticos e terrestres. O predomínio espaço-temporal de detrito/sedimento e vegetais na dieta indicou hábito alimentar detritívoro com tendência a herbivoria. Diferenças significativas na proporção dos itens alimentares ocorreram entre os meses e locais amostrados, tendo sido relacionadas à disponibilidade dos recursos, caracterizando o oportunismo trófico da espécie.

Diet-morphology relationship in the stream-dwelling characid Deuterodon stigmaturus (Gomes, 1947) (Characiformes: Characidae) is partially conditioned by ontogenetic development

“…This indicates that other sources of variability, such as feeding plasticity independent of the measured traits, are important factors influencing feeding of this species. This result is not surprising given previous studies that demonstrated the great feeding plasticity of fishes in relation to resource availability, mainly for characid species (Amundsen et al, 2001;Abelha et al, 2006;Uieda & Pinto, 2011;Manna et al, 2012). For Deuterodon, Vitule et al (2008) also found a great variability in the diet of D. langei individuals.…”

The coexistence of endemic species of Astyanax(Teleostei: Characidae) is propitiated by ecomorphological and trophic variations

“…13,no. 3 in large amounts during the early operation phases of reservoir and consumed by several fish species (Abelha et al 2006, Hahn & Fugi 2008. In this way, the opportunistic behavior of Astyanax species that exploit resources with high availability is corroborated.…”

Reproductive and feeding biology of Acestrorhynchus pantaneiro Menezes, 1992 (Osteichthyes: Acestrorhynchidae) in areas under the influence of dams in the upper Uruguay River, Brazil

“…Knowledge of the food resources that are available to fish populations and possible variations in their diets is an initial step to understand the processes involved in the establishment of the species in reservoirs (Abelha et al, 2006). Studies with A. pantaneiro in the Pantanal Matogrossense demonstrate that this species feeds on shrimp and fish in the same ratio (Resende et al, 1996), whereas in the Tibagi River, another species of peixe-cachorro, A. lacustris, includes in its diet, although accidentally, plants and insects (Benneman,1996).…”