Landscape changes in medium term: consequences for the composition, trophic structure and functional diversity of fish fauna in tropical streams.

Abstract

The successive changes in land-use over the years have potential to affect aquatic organisms. The aim of this project is assess if, and how, the landscape changes in medium term (one decade) can affect the stream fishes in multiple aspects, like community structure, trophic structure and functional diversity. For this, we'll be at least 30 streams with change in land-use (grasslands to sugar cane) and 10 control streams, where the land-use remained unchanged. All these streams were sampled in 2003-2004 at Northwest state of São Paulo and will be resampled in 2013, following the same methodology: two electrofishing passes with stationary generator of alternate current (220 V, 50-60 Hz, 3.4-4.1 A, 1000 W) in stretches of 75m in each stream. The 2003-2004 samples will be compared with 2013 as for: (i) composition, richness and diversity of stream fishes; (ii) trophic structure (trophic guilds identification); and, (iii) functional diversity based in trophic and ecomorphological traits (similarity dendrograms and MPD "mean pairwise distance" and MNTD "mean nearest taxon distance"). In addition, landscape analysis for watersheds in 2003-2004 and 2013 will be conducted with help of software ArcGis 9, ArcMap 9.2 version. To assess if, there is a correlation of biotic and abiotic streams variables with the landscape metrics and indices, which are explanatory variables, will be build a multiple regression model, to identify possible changes in land-use and the consequences for the stream fishes. Thus, the results will be useful the development of conservation, management and restoration action for river and stream ecosystems, especially in highly disturbed areas by agriculture.