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Composition and trophic organization of the ichthyofauna of Rio Capivara (Botucatu, SP): a time scale analysis

Grant number: 13/01968-9
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): May 01, 2013
Effective date (End): December 31, 2013
Field of knowledge:Biological Sciences - Ecology
Principal Investigator:Virginia Sanches Uieda
Grantee:Pedro Sartori Manoel
Home Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

The stream´s ichthyofauna is mainly represented by small fishes, characterized for having a great flexibility and adjustability with temporal and spatial changes in the habitat. Among these changes, siltation from human actions can result in a great loss in spatial heterogeneity and resources supply. Over the last decade, the Capivara River (Botucatu, SP) has been suffering a severe process of siltation caused by the removal of riparian vegetation for pasture establishment and Eucalyptus plantation, with changes in particle size of the substrate and a decrease in the water volume. The objective of this project is to verify how this process of siltation in the Capivara River may have influenced the composition and diet of the ichthyofauna. This analysis will be realized comparing data from a master´s dissertation realized in 1992/1993 and data that will be collected in 2013, both in the stretch located at Indiana Farm. Fish will be sampled in February and August 2013, rainy and dry seasons, respectively, to analyze the species composition and diet. As to the results of 1992/1993, the data of species composition will be extracted from the dissertation and papers already published, while data of the diet were provided for use in the present work. The hypothesis is that the major loss of environmental heterogeneity due to the ongoing process of siltation have influenced the occurrence of benthonic species, which depend on the bedrock substrate for reproduction and feeding, and of nektonic species that require a minimum volume of water to forage. It is also expected that this simplification of habitat has reduced the supply of resources and probably simplified the diet of fish species.