Benthos is recognized to strongly influence sediment stability, deposition, and erosion. This is well studied on small scales, but large-scale impact on morphological change is largely unknown. We quantify the large-scale impact of benthos by modeling the evolution of a tidal basin. Results indicate a profound impact of benthos by redistributing sediments on large scales. As confirmed by measurements, including benthos significantly improves model results compared to an abiotic scenario.