Morpho‐Ecological Restoration in Braided Rivers: The Need to Account for Geomorphological Heterogeneity

ABSTRACT Braided rivers display a wide range of ecological conditions associated with their specific morphological and hydrological dynamics. Like other hydrosystems, braided rivers have been altered by human activities, which have led to a loss of their multi‐thread morphology, causing severe damage to their ecological functioning. River restoration has been a major research focus in the last three decades due to the Water Framework Directive recommendations to improve the ecological status of water bodies and encourage researchers to develop indicators for assessing ecological status. However, generic indicators developed to fulfill the WFD recommendations often underestimate the specificities of river types such as multi‐thread braided rivers. In this study, we adapted the current French sampling methodology for collecting benthic invertebrates for a braided alpine river by considering the diversity of macro‐, meso‐, and microhabitats within reaches. We applied this modified methodology to compare invertebrate assemblages (abundance, diversity, taxonomic and trait composition) in a braided alpine river, using one restored and one semi‐natural (i.e., target) reach. Five years after restoration, the target reach was more diversified in terms of macrohabitats (channel types) compared to the restored reach. This resulted in a higher taxa and trait diversity. These results give insights into the significance of channel type diversity in supporting benthic invertebrate assemblages in braided rivers and the need to adapt invertebrate sampling methodologies to consider their multi‐thread morphology.