13 research outputs found
Variability in the trophic position of larval fishes in theupper ParanĂĄ floodplain based on δ15N
The upper ParanĂĄ River floodplain is composed of several marginal lagoons, making it a natural breeding ground for many fish species at developmental stages. The aim of this study is to estimate the trophic positions of these fishes based on feed intake (measured via diet) and nitrogen assimilation (measured via δ15N). The monthly samplings were concentrated during the spawning season in the Ivinheima River, which is located in the upper ParanĂĄ River floodplain. The specimens were grouped into preflexion, flexion and postflexion stages. Trophic positions were estimated based on the isotope value of nitrogen and on diet. During the developmental stages of P. squamosissimus, there were significant differences in the isotope values of δ15N; for H. edentatus, however, no significant differences were found. During the developmental stages, both species were classified as either at or above the third trophic level. Once this information is obtained for other species and components of the ecosystem, it will not only provide a more precise view of the energy allocation and flow in the ecosystem, but will also make possible for management measures to promote sustainability in this environment.<br>A planĂcie de inundação do alto rio ParanĂĄ Ă© formada por vĂĄrias lagoas marginais, tornando-se um criadouro natural de vĂĄrias espĂ©cies de peixes nos estĂĄgios de desenvolvimento. O objetivo do estudo foi estimar as posiçÔes trĂłficas destes peixes, com base no alimento consumido (medido atravĂ©s dieta) e o nitrogĂȘnio assimilado (medido atravĂ©s δ15N). As amostragens mensais concentraram-se no perĂodo de desova das espĂ©cies, no rio Ivinheima, na planĂcie de inundação do alto rio ParanĂĄ. Os espĂ©cimes foram agrupados em: prĂ©-flexĂŁo, flexĂŁo e pĂłs-flexĂŁo. As posiçÔes trĂłficas foram estimadas com base no valor isotĂłpico de nitrogĂȘnio e na dieta. Nas fases de desenvolvimento de P. squamosissimus houve diferença significativa nos valores isotĂłpicos de δ15N, enquanto que, para H. edentatus, nĂŁo foram identificadas. Ambas as espĂ©cies, durante os estĂĄgios de desenvolvimento, foram classificadas em igual ou acima do terceiro nĂvel trĂłfico. Estas informaçÔes, quando obtidas para outras espĂ©cies de peixes e componentes do ecossistema, fornecerĂŁo uma visĂŁo mais precisa da distribuição e fluxo de energia no ecossistema, alĂ©m de tornar possĂvel medidas de manejo, que visem promover a sustentabilidade deste ambiente