Influence of macro and mesohabitats on fish distribution of Atlantic Forest Blackwater Rivers

Abstract

Blackwater Rivers represent an important fraction of Atlantic Forest lotic environments, however information on its fish populations and its relationship with different spatial scales as macro and mesohabitats are still poorly understood in southeastern Brazil. This project aims to delimit the main macro and mesohabitats of some blackwater rivers located in the State Park of the Restingas of Bertioga - SP, in order to verify the influence of local spatial scale on the structure, composition and functional aspects of the fish communities. After a pilot sampling, up to twelve rivers will be selected in the dry season, adapting a classification of macro and mesohabitats. Fish will be sampled with electrofishing in each of macrohabitats (rivers) and mesohabitats, after morphological characterization of habitats parameters, and physical and chemical water quality. Total organic carbon content (TOC) and dissolved (DOC) will also be measured, since these environments possess high content of humic acids, which may be related to the composition and biomass of fish communities. Environmental data and fish populations will be grouped by macro and mesohabitat to calculate the abundance, biomass, richness and Shannon diversity, as well as the proportion of different functional groups. Data will be analyzed through an exploratory analysis, including multivariate analysis techniques such as scaling analysis Non-Metric Multidimensional Scaling (NMDS) and Canonical Correspondence Analysis to correlate species and environmental variables. The TOC and DOC data will be correlated to the biomass and abundance of fishes through linear techniques and simple correlations. Results will help to understand the species distribution patterns in these ecosystems, and to support river monitoring programs, as well as help to predict and evaluate the effects of anthropogenic pressures on similar ecosystems. (AU)