Ecomorfologia refletindo a dieta dos peixes em um reservatório no sul do Brasil

Abstract

The Capivara Reservoir is located at the Medium Paranapanema river, between the states of Paraná and São Paulo and was formed in 1977. Samples made in 2001 and 2002 yielded 62 fish species, 31 of which occurred in the studied stretch. The nine most abundant species were chosen for the ecomorphological analysis. Eight ecomorphological attributes related to habitat use and foraging were employed in order to identify existing ecomorphological patterns among the species as well as relating them to the main food item consumed by each one. A cluster analysis based on the alimentary index (IAi) data grouped the species according to the main food items consumed. Principal component analysis related piscivores to large heads, caudal fins and terminal mouth with pungent teeth; benthic-dwelling fishes were related to small, subterminal mouths and reduced or absent dentition; omnivores attributes reflected taxonomic relatedness rather than any ecomorphological adaptation; herbivores were related to small mouths and multicuspidated dentition. The resulting trophic groups relative abundances agreed to the general pattern observed in reservoirs, showing a predominance of piscivores, detritivores and omnivores. Cichla monoculus (Spix & Agassiz, 1831) and Plagioscion squamosissimus (Heckel, 1840) showed large trophic and ecomorphological overlaps meaning that resource use by both species is probably highly similar. Thus ecomorphology seemed to be a suitable tool for describing habitat preferences as well as the prey capture behavior of piscivore species.Keywords: freshwater fishes, numeric ecology, community ecology, trophic ecology. Oito atributos ecomorfológicos relacionados ao uso do habitat e alimentação foram usados com objetivo de distinguir padrões ecomorfológicos entre as espécies e relacioná-los ao principal alimento consumido. Um dendrograma de similaridade alimentar foi construído a partir dos resultados do Índice Alimentar (IAi), agrupando as espécies conforme os principais alimentos consumidos. Pela análise de componentes principais piscívoros foram relacionados a cabeças, nadadeiras caudais e bocas terminais grandes com dentes pungentes; peixes bentófagos foram relacionados a bocas pequenas e subterminais e dentição pouco desenvolvida ou ausente; peixes onívoros revelaram atributos relacionados mais à afinidade taxonômica que a adaptações ecomorfológicas; peixes herbívoros foram relacionados a boca pequena e dentes multicuspidados. Os resultados mostraram que as abundâncias relativas dos grupos tróficos estiveram de acordo com o padrão geral observado em reservatórios, com predomínio de piscívoros, detritívoros e onívoros. Cichla monoculus (Spix & Agassiz, 1831) e Plagioscion squamosissimus (Heckel, 1840) apresentaram grande semelhança ecomorfológica e trófica entre si, permitindo concluir que o uso dos recursos por ambas as espécies é também bastante semelhante. A ecomorfologia se mostrou uma ferramenta adequada na descrição das preferências de habitat das espécies e de aspectos de comportamento de captura de pr...

Biological aspects of Schizodon nasutus Kner, 1858 (Characiformes, Anostomidae) in the low Sorocaba river basin, São Paulo state, Brazil

“…Several authors describe the gender Schizodon as an herbivorous one (Santos, 1982;Bennemann et al, 1996Bennemann et al, , 2000Bennemann et al, , 2006Meschiatti, 1995;Ferretti et al, 1996;Resende, 2000;Marcal-Simabuku and Peret, 2002;Pompeu and Godinho, 2003;Pereira et al, 2004;Teixeira and Bennemann, 2007). The item Poaceae (grass) was the most significant one in the whole period observed, since it presented the highest frequencies and dominance, reflecting the availability of this alimentary item, because they are usually found in abundance on the margins of Sorocaba river, being even more accessible during the rainy period.…”

“…Schizodon nasutus Kner, 1858, presents a small and subterminal mouth, which indicates it feeds on small-sized items and is able to get its food in middle or deep waters. Their general morphology indicates that they may be classified as good swimmers whose external aspect is typical of migratory fish (Teixeira and Bennemann, 2007), found in lagoons and rivers (Hahn et al, 2004).…”

Feeding ecology of Dash-dot Tetra Hemigrammus belottii(Steindachner 1882) (Characiformes: Characidae) in the streams of the Urucu River basin, central Amazonia, Brazil

“…The relative weight (W i %) of each item was calculated by W i % = m i /N * 100, where m i represents the weight in grams of item i and N is the total weight of all items in the stomachs (Hyslop 1980). These two methods were combined to obtain the Alimentary Index (AI i %), which evaluates the importance of each item to the composition of the diet of the species (Kawakami & Vazzoler 1980, Teixeira & Bennemann 2007, and is calculated by the formula:…”

Morphological differentiation among migratory fish species from the Paraná River basin

“…Studies on morphology of Neotropical freshwater fish are restricted to the comparison between morphology and diet (Piorski et al 2005, Teixeira & Bennemann 2007, morphological variations under different environmental conditions (Monteiro & Neves 2003), and ecomorphology of fish from streams (Casatti & Castro 2006, Ferreira 2007. However, studies on the morphology associated with swimming performance for the Neotropical fish species are non-existent, with only information available for two migratory species, Leporinus reinhardti and Pimelodus maculatus, on swimming speeds and determination of swimming performance in the studies conducted by Santos et al (2007Santos et al ( , 2008.…”