Relationships among macroinvertebrate community structure, bio/ecological trait profiles, and environmental descriptors in European human-altered streams

Over the last decades, depletion in freshwater quality due to increasing pollution has become an important problem, especially in Europe where most streams drain catchments that are relatively densely populated. Effluents from waste water treatment plants (WWTP) represent one of the causes of stream ecosystem degradation (PAUL & MEYER 2001). This attains special relevance in Mediterranean countries, where the scarcity of water limits the dilution of pollution. In this context, the use of adequate ecological indicators is particularly helpful in assessing the impact of environmental changes (JOHNSON et al. 2006). Macroinvertebrates are good indicators of stream pollution (e.g., biotic indices) successfully used in monitoring studies (VERDONSCHOT & MOOG 2006). Recently, the use of trait profiles has enabled a reliable ecological indication, not only characterizing community structure (CHARVET et al. 1998), but also permitting the functional comparison of communities across larger geographical scales (DOLEDEC et al. 2006). This study evaluated the impact of WWTP inputs on stream functioning under different climatic conditions across Europe. We investigated the relationships between macroinvertebrate communities (i.e. taxonomic composition and traits profiles) and environmental variables in two ecologically contrasted reaches (upstream and downstream a WWTP) for 10 European streams