Different scales of analysis in classifying streams: from a multimetric towards an integrated system approach

Two different approaches to define the ecological status of several catchments (NW Portugal) are compared. At a coarser scale, all the stream network was classed using GIS according to several variables related to: a) biotic indicators, such as native and exotic fish species, benthic biotic index and characteristics of the riparian corridor); b) chemical indicators of contamination, where an estimation of industrial and urban organic loads and water quality was included. This methodology is preceded by a typological classification so that a determination of the ecological status can be made separately of each of the physical units integrated in the watercourse.