The particularly rich aquatic biodiversity of large river floodplains is structured by river dynamics and hydrological connectivity. Subjected to very high pressure from river uses and engineering (e.g. hydropower, dams, dykes), large rivers undergo physical (loss of diversity of floodplain habitats) and functional (loss of lateral hydrological connectivity) changes in their floodplain habitats. The significant degradation of these habitats and the associated biodiversity has led to a desire to limit the impacts of human activities and restore floodplain environments. The aim of the present thesis is to explore the relationship between hydrological connectivity and biological processes (taxonomic diversity and trophic transfers) in large river floodplains. To this end, a multidisciplinary (geomorphology, biology and ecology), multi-compartment (plankton, invertebrate and fish) and multi-scale (channel vs. floodplain) approach was adopted. Two floodplains of the French Upper Rhône comprising restored channels characterized by variable connectivity with the river were selected as study sites. The results confirm the strong influence of hydrological connectivity on the composition of invertebrate assemblages at both the individual channels and the entire floodplain. They also confirmed the aquatic invertebrate diversity varies in response to two components of the hydrological connectivity (upstream overflows with hydraulic constraints and so-called "slow" connections) at both spatial scales.