Testing predictions of changes in benthic invertebrate abundance and community structure after flow restoration in a large river (French Rhône)

摘要: Summary Principal threats to running waters are linked human-made discharge modifications, but tools predict the quantitative consequences of flow restoration for benthic invertebrates in large rivers remain untested. Quantitative benthos samples from two bypassed reaches (Pierre-Benite – PBE and Chautagne CHAU) French Rhone River were collected during four years each before after minimum increases (from 10 100 m3 s−1 at 50 m3 s−1 CHAU). These provided observed ln-density changes 50 62 (PBE CHAU, respectively) most abundant taxa (typically species or genera). For about half ‘model’ among them, distinct preference models bottom shear stress categories available Upper various German rivers. Linking these with a statistical hydraulic model predicting frequencies any given discharge, we predicted restoration. Community structure changed clearly rapidly less CHAU. Our predictions explained considerable amount mean our (75 30% respectively). They also (67 40% scores along principal components analysis axis that summarised community variations all restoration. not identified (assessed as genus, tribe family), sometimes inaccurate (a Lower site), suggesting transferability taxonomic levels above can be problematic. If further developed, habitat focussing on ecologically relevant physical variables (in case stress) should enable reliable assessments associations between efforts achievable ecological improvement.