Habitats' local structure and connectivity in river basins at the southern coast of the State of São Paulo: a GIS approach

Abstract

Fragmentation and loss of habitat are responsible for the reduction of biological diversity in river systems. Patch area and environmental complexity are related to local patterns of diversity, while stream topology (i.e. structural connectivity) affects patterns of regional diversity and organisms' dispersion over aquatic ecosystems. Recently, spatial graphs are being used to represent patterns of regional connectivity among habitat patches in ecological systems. Therefore, the objective of this project is to map Baixada Santista`s coastal river basins using data from Geographic Information Systems (GIS) to obtain metrics that describe stream segments in local (elevation, area, declivity) and regional scales (network`s topology). As a result, the river basins will be placed in a Cartesian system that will represent structural complexity degree and local habitats` structure. We hypothesized that, generally, larger basins are also structurally more complex. However, to understand how is the relative influence of each axis on the formation of fluvial systems at Baixada Santista, it is necessary to place them as a function of the network`s sensibility to multiple scales anthropologic impacts. (AU)