RÉSUMÉ Effets à long-terme des changements globaux et locaux sur les communautés de ma-croinvertébrés benthiques des grands fleuves anthropisés : exemple du Rhône au cours des 30 dernières années

Key-words: freshwater macroinvertebrates, Rhône River, climate change, long-term survey, biological traits, alien species The study of biological traits have enhanced the understanding of the changes in the macroinvertebrate communities of the Rhône River during the last thirty years, as well as the potential effects of hydroclimatic factors and thermal discharges on the structure and the functioning of these communities at the regional scale. If every section of the Rhône had specific features, we observed over time a trend towards a higher uniformisation of invertebrate communities, especially in the Lower section. The strong impacts of the alien species and the water warming subsequent to the 2003 heat wave have been detected in the Lower Rhône and the Middle Rhône: the communities of the Middle Rhône gradually exhibit profiles closer to those of the communities of the Lower Rhône. The Upper Rhône was less colonized by alien species but was impaired by the global warming: its communities exhibited biological profiles closer to those of communities of further-downstream zones. In this site, the thermal discharges have led to a lower diversity of the communities and a higher occurrence of eurythermic species. Hence the benthic macrofauna of the Rhône River seems to have reacted quickly and strongly to environmental changes and to the arrival of invasive species. However numerous trait adaptations being common to Mediterranean and alien species, it seems complex to evaluate the respective weight of each of these potential sources of impairment. Predicting trends in invertebrate community composition is a complex objective because of the competition between native and/or invasive species in addition to man-induced environmental variation (flow, temperature). However, if biological invasion does not occur continuously but only based on specific events (especially hydroclimatology), we can legitimately believe that this drift will continue with the arrival of new Ponto-Caspian species via the Danube-Main Canal, their usual way to western and southern Europe. The common feature of these different species is that they are essentially predators or filterers, thermophilic and euryecic, and efficient functional competitors. Finally, this study once again emphasizes the importance of long-term monitoring in the study of biological communities in the context of global warming. (1) ARALEP, Campus LyonTech-La Doua, 66 Bld Niels Bohr, CS 52132, 69603 Villeurbanne Cedex, France (2) Present adress: UMR 7208 BOREA – IRD 207, MNHN, 43 rue Cuvier, 75231 Paris Cedex, France (3) IRSTEA Aix-en-Provence, 3275 Route de Cézanne, CS 40061, 13182 Aix-en-Provence Cedex 5, France (4) IRSTEA Lyon, 5 rue de la Doua, CS 70077, 69626 Villeurbanne Cedex, France Corresponding author: fruget@aralep.com This is an Open Access article distributed under the terms of the Creative Commons Attribution License CC-BY-ND (http://creativecommons.org/licenses/by-nd/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. If you remix, transform, or build upon the material, you may not distribute the modified material. J.-F. Fruget et al.: Knowl. Manag. Aquat. Ecosyst. (2015) 416, 29