Current Practices on the Water Frame Directive implementation in Spain: Problems and Perspectives

Abstract

River typologies and methods for selecting reference sites and reference conditions are being discussed in Spain, starting from a single-scale, taxonomic classification of rivers and a relative experience on the use of biotic indexes for water quality monitoring. The present reductionistic tendency of using the biotic indexes for defining biological reference conditions is discussed, attending to the loosing of basic biological information and precision that occurs when the species composition list and abundance structure are expressed in single numbers. Ideas for alternative methods are presented, including a hierarchical, multiple-scale river classification scheme, from which selection of reference sites can be made, according to the status of hydromorphological and water quality elements. The importance of achieving the finest taxonomic resolution of the biological data for defining the reference conditions is remarked, in order to establish a solid, scientifically based pool of data from which the ecological status of rivers can be precisely estimated, preserving the peculiarities of each river type.