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Influence of predation and local physical characteristics on the structure of functional groups and planktonic food web in a flood plain

Abstract

This project aims at assessing how the predation and local physical characteristics, provided by flood pulses, will affect the functional structure of the assemblages and planktonic trophic relationships in a flood plain. The hypothesis is that the connectivity between the river and adjacent systems will provide the exchange of biota and changes of abiotic variables of the water, which can modify the functional structure of the zooplankton community and change the trophic relationships in aquatic communities of oxbow lakes. To assess if the connection to the river affects zooplankton functional diversity, functional groups of zooplankton will be compared between communities of oxbow lakes and ponds communities that differ on hydrological characteristics. In order to check if the flood pulses affect the trophic structure, planktonic trophic relationships will be characterized, into two distinct periods: the wet season, when there is no connection between lakes and river and rainy season, where flood pulses provide the connection. The oxbow lakes are located in the floodplain of the Turvo river (20º25'S, 49º16'W). Samples will be taken from algae, zooplankton and fish communities for the trophic relationships will be evaluated through the analysis of stomach contents. Physical and chemical factors as the water depth, temperature, pH, conductivity, dissolved oxygen, chlorophyll-a and nutrients will be assessed. In order to verify the direct influence of predation by fish and planktonic invertebrates on the structure of zooplankton communities, in situ experiments will be conducted by enclosures with three treatments: 1. only the zooplankton community; 2. zooplankton and macrophytes; 3. zooplankton and fish. These results will help to answer more specific questions about population structure, such as the size and trophic structure. (AU)

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VEICULO: TITULO (DATA)
VEICULO: TITULO (DATA)