Trophic structure of a fish community along environmental gradients of a subtropical river (Paraitinga River, Upper Tietê River Basin, Brazil)

Abstract

This research characterized the feeding ecology of the fish community of the upper-middle course of Paraitinga River, located within the Upper Tietê River Basin, a peculiar Atlantic Forest area, regarded as a hotspot for fish conservation. Considering the several anthropogenic modifications, knowledge of the trophic structure might contribute to a better understanding of the factors that maintain the present fish community. Fish were collected with electrofishing equipment at 16 sites with different riparian vegetation, including native forest, secondary forest, pasture, and Eucalyptus, during the dry and rainy season of 2004/2005. Results obtained for 15 species indicated a predominance of insectivores and herbivore-detritivores along the course and an increase of total biomass, specifically of the herbivores-detritivores at the pasture sites, which seemed to be mediated by specific habitat features, which included open canopy, high water speed, and deeper areas. Strategies of resource use indicated that 47% of total combination pairs showed high overlap, but competition seemed to be minimized through low co-occurrence, spatial segregation, and abundance of food resources. Niche width was broad for all species, with no significant differences occurring among sites, seasons, and upper and lower course. With regard to the ongoing modifications in riparian zone conditions in this area, the implications of these findings for regional biodiversity conservation are discussed.

Aquatic insects as the main food resource of fish the community in a Neotropical reservoir

“…These results, combined with the low niche breadth of all species suggest a high degree of food partitioning among species, and has been observed in other fish communities of the Neotropical region (Uieda et al, 1997;Esteves et al, 2008;Novakowski et al, 2008;Mérona & Rankin-de-Mérona, 2004). However, when overlap was analyzed independently within each trophic guild, some different patterns were observed.…”

Diet of Astyanax paranae (Characidae) in streams with different riparian land covers in the Passa-Cinco River basin, southeastern Brazil

“…The feeding habits reported in the literature for this species in the upper Paraná River system were insectivorous and omnivorous, both in streams and rivers habitats (uieda et al, 1987;castro & casatti, 1997;uieda et al, 1997;roque et al, 2003;oliVeira & bennemann, 2005;Ferreira, 2007;esteVes et al, 2008;Ferreira et al, 2012), and detritivore in a reservoir (abelha et al, 2006).…”

“…Riparian land cover changes also trigger changes in stream fish fauna (roWe et al, 1999;GroWns et al, 2003). Allochthonous food sources for stream fish are being destroyed even before there is a better understanding of the interaction between the environment and the ichthyofauna (esteVes & aranha, 1999).…”

Compartilhamento de recursos por duas espécies de peixes nectobentônicas de riachos na bacia do rio Cachoeira (BA)

“…no rio Passa Cinco (Rondineli et al 2009), em um riacho no Parque Estadual do Morro do Diabo (Casatti 2002(Casatti , 2003, em riachos no Chile (Habit et al 2005) e na Colômbia (Chará et al 2006). Espécies dos gêneros Characidium e Trichomycterus amostrados em riachos de Mata Atlântica foram classificadas como insetívoras, com preferência por insetos aquáticos, em diversos estudos (Sabino & Castro 1990, Castro & Casatti 1997, Aranha et al 1998, Esteves & Lobón-Cerviá 2001, Motta & Uieda 2004, Castro et al 2004, Barreto & Aranha 2006, Esteves et al 2008, Rondineli et al 2009). A elevada participação de grupos cujas fases larvais são aquáticas ou semi-aquáticas demonstra a importância da contribuição dos insetos aquáticos para a ecologia dos sistemas terrestres adjacentes e para a própria dinâmica do corpo d'água, uma vez que parte desses indivíduos retorna para o sistema aquático (Roque et al 2003).…”

“…foi verificada por Esteves & Lobón-Cerviá (2001) em um riacho de Mata Atlântica, mas houve segregação espacial entre as espécies, com a primeira ocorrendo em locais mais profundos e a segunda em locais mais rasos. Na escala temporal, Casatti & Castro (1998) Esteves et al (2008) o comportamento de "senta-e-espera", com captura das presas após inspeção visual, pode ser um mecanismo para evitar a competição.…”