Benthic fauna-mediated bed load sediment transport dynamics

Benthic fauna plays a critical role in mediating bed load sediment transport, an essential process influencing wetland restoration, water quality, coastal protection, and nutrient cycling. However, predictive models quantifying this biological mediation remain absent due to limited mechanistic understanding. Here, we develop a high-fidelity computational model coupling fluid flow, sediment dynamics, and benthic activity to quantify benthic fauna-mediated bed load transport. We show that benthic presence can reduce transport rates by up to 50%, primarily through two mechanisms: bioroughness-induced effective shear stress reduction and bioturbulence-driven wake zone expansion. Building on these insights, we propose two predictive formulas that align well with field data. These findings offer the first quantitative framework for bed load prediction in benthos-dominated environments and sheds light on sediment dynamics central to benthic morphodynamics.