Application of catchment- and local-scale variables for aquatic habitat characterization and assessment in the brazilian semi-arid region

Abstract

The state of the physical habitat is influenced by factors operating at several spatial and temporal scales, such as geomorphology, climate, hydrology, land use and water quality. This work measures diversity and availability of the physical habitat in natural and artificial aquatic systems in the northeast of Brazil. It aims to survey local- and catchment-scale physical variables and evaluate their importance as a basic framework for characterization and assessment of aquatic habitats in the Brazilian semi-arid region. This study was performed in two areas of the Brazilian semi-arid (Serido/Borborema and Buique/Vale do Ipojuca), classified as being of extreme biological importance and identified as priority areas for biodiversity conservation in the Caatinga. The present study showed that the aquatic habitat in semi-arid Brazil is diverse and dynamic, with a range of habitat elements available for colonization by the aquatic biota. Stream sites showed a similar to greater array of marginal habitat elements and substrate composition when compared to reservoirs, and the composition of the habitat varied with habitat type (river/reservoir) and seasons (dry/ wet). Results presented have implications for the conservation and management of Brazilian semi-arid systems. Given that the habitat is the basic framework for colonization of aquatic organisms, the potential mechanisms that maintain biotic diversity lie at all levels of the river watershed. It is fundamental therefore, to identify the parts of the riverine ecosystems that are vital to maintaining its health