This study investigates the morphological parameters and migration rates of dune systems associated with a set of banner banks located at intermediate depths (50 m to 120 m) in the context of a highly dispersive shelf, offshore Brittany (Western France). The work mainly focuses on the Haut Fond d’Ouessant bank. New geophysical data (bathymetry, seismic, reflectivity) from Speedunes (2015) and Bankable (2019) cruises are analysed. We examine how the large range in basal surface depth over which the bank lies affect the dune morphodynamics. We also characterize sediment fluxes between these sediment structures, toward an overview map of sediment pathways across the Iroise shelf, in relation with the straits and the irregular shelf bottom