Spatial, seasonal and ontogenetic variation in the diet of Astyanax aff. fasciatus (Ostariophysi: Characidae) in an Atlantic Forest river, Southern Brazil
Abstract:This study described the feeding habits of the characin Astyanax aff. fasciatus. The diet compositions of specimens from two sites (A and B) on a river in Southern Brazil were compared according to the size of individuals and seasonal period. The collections were performed monthly from March 2005 to February 2006, where the stomach contents of 290 specimens were assessed. Food items for A. aff. fasciatus were basically composed of plants and insects, especially leaf fragments, seeds, fruits, filamentous algae,… Show more
“…In the Mato Grosso stream Astyanax taeniatus had a varied diet. Distinct feeding behaviour with high plasticity has been previously described for this genus (Costa, 1987;Cassemiro et al, 2002;Gomiero and Braga, 2003;Borba et al, 2008;Wolff et al, 2009). In this study, and in another by Bennemann et al (2005), the diet of Astyanax species was found to consist primarily of allochthonous insects and terrestrial plant debris, and changes in the consumption of these resources were related to physical changes in the environment.…”
Section: Discussionsupporting
confidence: 70%
“…This is also seen in other species of the Characidae family (e.g. Barreto and Aranha, 2006;Wolff et al, 2009;Mazzoni et al, 2010a), indicating that the relationship between intestine length and the standard length of a species varies during the growth of an individual (Mazzoni et al, 2010a). The intestinal quotient (Qi) can be a useful tool for evaluating ontogenetic variations in the diet of fish (Zavala-Camim, 1996), and an increase in the intestinal quotient of adults may be associated with high plasticity, the capacity for food spectrum expansion (Andrian et al, 2001) and the utilization of less digestible (e.g.…”
In this work we aimed to characterise the diet of Astyanax taeniatus (Jenyns 1842) (Characiformes, Characidae) along the Mato Grosso stream and we hypothesised that the diet of this species would vary according to spatial, seasonal and ontogenetic differences. Specimens were collected every second month at three sites with different physical attributes. The feeding habits of 651 specimens were analysed using the Alimentary Index (IA i ). Analysis of the diet showed an effect of spatial, temporal and ontogenetic factors. Vegetal allochthonous items were more important in the diet of Astyanax taeniatus in upstream sites while animal autochthonous items were more important downstream. Ontogenetic differences in the diet were significant only in upstream sites, where adults consumed a greater amount of vegetal matter than juveniles. These results reinforce the idea that Astyanax species are opportunistic and show trophic plasticity.Keywords: feeding, opportunism, stream fish.
Plasticidade trófica em Astyanax taeniatus de um riacho costeiro do Sudeste do Brasil ResumoNeste trabalho, objetivou-se caracterizar a dieta de Astyanax taeniatus (Jenyns 1842) (Characiformes, Characidae) ao longo do Rio Mato Grosso, com a hipótese de que a espécie apresente variações espaciais, sazonais e ontogenéticas. Os exemplares foram coletados bimestralmente em três localidades, que diferiram pelas variáveis físicas. As preferências alimentares foram analisadas a partir de 651 exemplares, utilizando-se o Índice Alimentar (IA i ). Foram avaliadas diferenças espaciais, sazonais e ontogenéticas a partir dos dados de dieta. Os itens de origem vegetal e alóctone foram mais importantes na dieta da espécie para as localidades com maior altitude, enquanto os itens animais e autóctones, na localidade baixa. Na dieta de jovens e adultos, houve diferença significativa na contribuição de itens de origem vegetal e animal somente na localidade mais alta, onde os adultos consumiram maior quantidade de matéria vegetal. Os resultados reforçam a ideia de que as espécies de Astyanax possuem hábito alimentar onívoro e oportunista, evidenciando sua alta plasticidade alimentar ao longo do riacho.Palavras-chave: alimentação, oportunismo, peixe de riacho.
“…In the Mato Grosso stream Astyanax taeniatus had a varied diet. Distinct feeding behaviour with high plasticity has been previously described for this genus (Costa, 1987;Cassemiro et al, 2002;Gomiero and Braga, 2003;Borba et al, 2008;Wolff et al, 2009). In this study, and in another by Bennemann et al (2005), the diet of Astyanax species was found to consist primarily of allochthonous insects and terrestrial plant debris, and changes in the consumption of these resources were related to physical changes in the environment.…”
Section: Discussionsupporting
confidence: 70%
“…This is also seen in other species of the Characidae family (e.g. Barreto and Aranha, 2006;Wolff et al, 2009;Mazzoni et al, 2010a), indicating that the relationship between intestine length and the standard length of a species varies during the growth of an individual (Mazzoni et al, 2010a). The intestinal quotient (Qi) can be a useful tool for evaluating ontogenetic variations in the diet of fish (Zavala-Camim, 1996), and an increase in the intestinal quotient of adults may be associated with high plasticity, the capacity for food spectrum expansion (Andrian et al, 2001) and the utilization of less digestible (e.g.…”
In this work we aimed to characterise the diet of Astyanax taeniatus (Jenyns 1842) (Characiformes, Characidae) along the Mato Grosso stream and we hypothesised that the diet of this species would vary according to spatial, seasonal and ontogenetic differences. Specimens were collected every second month at three sites with different physical attributes. The feeding habits of 651 specimens were analysed using the Alimentary Index (IA i ). Analysis of the diet showed an effect of spatial, temporal and ontogenetic factors. Vegetal allochthonous items were more important in the diet of Astyanax taeniatus in upstream sites while animal autochthonous items were more important downstream. Ontogenetic differences in the diet were significant only in upstream sites, where adults consumed a greater amount of vegetal matter than juveniles. These results reinforce the idea that Astyanax species are opportunistic and show trophic plasticity.Keywords: feeding, opportunism, stream fish.
Plasticidade trófica em Astyanax taeniatus de um riacho costeiro do Sudeste do Brasil ResumoNeste trabalho, objetivou-se caracterizar a dieta de Astyanax taeniatus (Jenyns 1842) (Characiformes, Characidae) ao longo do Rio Mato Grosso, com a hipótese de que a espécie apresente variações espaciais, sazonais e ontogenéticas. Os exemplares foram coletados bimestralmente em três localidades, que diferiram pelas variáveis físicas. As preferências alimentares foram analisadas a partir de 651 exemplares, utilizando-se o Índice Alimentar (IA i ). Foram avaliadas diferenças espaciais, sazonais e ontogenéticas a partir dos dados de dieta. Os itens de origem vegetal e alóctone foram mais importantes na dieta da espécie para as localidades com maior altitude, enquanto os itens animais e autóctones, na localidade baixa. Na dieta de jovens e adultos, houve diferença significativa na contribuição de itens de origem vegetal e animal somente na localidade mais alta, onde os adultos consumiram maior quantidade de matéria vegetal. Os resultados reforçam a ideia de que as espécies de Astyanax possuem hábito alimentar onívoro e oportunista, evidenciando sua alta plasticidade alimentar ao longo do riacho.Palavras-chave: alimentação, oportunismo, peixe de riacho.
“…This high similarity between local and broader spatial distributions could be explained by: i) lacking larger migratory species in Iguaçu River basin that are deeper channel dwellers in the Paraná River and others tributaries (Agostinho et al 2003(Agostinho et al , 2008; ii) the wide ability of the characins of genus Astyanax to colonize practically all environments of basin, including large and small inland water or even reservoirs. This genus present broad distribution in low Iguaçu River basin (Garavello & Sampaio 2010), pronounced trophic plasticity (Wolff et al 2009, and were captured here, with high abundances in all streams independently of physiographic features and land use.…”
The fish fauna of eight streams with different land uses of their watersheds (forested and rural areas) in the lower Iguaçu River basin was inventoried, in order to evaluate the composition and species richness. The fishes were sampled quarterly from May 2015 to February 2016, using the electrofishing technique. In total, 4,239 individuals were captured, belonging to six orders, 11 families and 26 species. The orders Siluriformes and Characiformes, and the families Characidae and Trichomycteridae were the most specious. Of the total species sampled, 65% were endemic to the Iguaçu River basin, four are not described and four are non-native. As expected to the Iguaçu River basin, the inventoried fauna revealed low richness and high endemism, however was highly nested within the species composition reported for main channel of Iguaçu River and their larger tributaries. The species recorded here corresponded to a subset of 24.5% of the 106 species documented for the basin. The streams presented different faunas, with only two species (Astyanax bifasciatus and Trichomycterus stawiarski) common to both forested and rural streams. In addition, higher species richness was recorded in streams inserted in conservation units. The presence of non-native species was more frequent in rural streams. These results highlight the importance of the preservation of forested areas in the watersheds of lower Iguaçu, which presents a peculiar fish fauna, along with several threats to biodiversity such as habitat loss by intensive agriculture use.
“…Such is the case for surface Astyanax. A surface population studied by Wolff et al (2009) showed that in fish of less than 5 cm standard length, 75.8% of their diet by volume was made of animal items. In 5.1 to 7.5 cm long fish, animal content decreased to 28.6%, and when longer than 7.6 cm, its animal derived diet was reduced to 20.7% to the increase of plant items.…”
The subterranean environment is often described as "extreme" and food poor. Laboratory experiments have shown that blind Mexican tetra Astyanax mexicanus (De Filippi, 1853) cavefish are better at finding food in the dark than surface fish. Several morphological and behavioural attributes that could foster this obvious adaptive response to cave environments have been described. Nonetheless, it is currently unknown what young cavefish actually eat in their natural cave environment. Our results from the Pachón cave in México during the dry and rainy season show that fry are efficient predators in their natural cave environment. Their primary food item is aquatic crustaceans. The guts of post-larval, pre-juvenile stage individuals (n=9) contained an average of 17.9 water fleas (Cladocera), copepods, ostracods, and isopods. Thus, the fry in this cave are well-fed. The Pachón cave environment does not appear to be "food poor" for juvenile cavefish. Food regimes change between post-larval and adult stages to become more dependent on partially decomposed material, guano, or detritus from the mud. We discuss the data with regards to our current developmental and genetic understanding of cavefish morphological and behavioural evolution, particularly regarding its enhanced Vibration Attraction Behaviour (VAB).
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