Signal crayfish burrowing, bank retreat and sediment supply to rivers: A biophysical sediment budget

Burrowing into riverbanks by animals transfers sediment directly river channels and has been hypothesised to accelerate bank erosion promote mass failure. A field monitoring study on two UK rivers invaded signal crayfish (Pacifastacus leniusculus) assessed the impact of burrowing processes. Erosion pins were installed in 17 across a gradient burrow densities monitored for 22 months. Bank retreat increased significantly with density. At scale (<6 m length), high associated accelerated up 253% more than doubling area collapse compared banks without burrows. Direct supply activity contributed 0.2% 0.6% total at reach (1.1 km) local m) scales. However, caused burrows 12.2% 29.8% Together, acceleration supplied an additional 25.4 t km−1 a−1 floodplain sediments one site, demonstrating substantial that can have fine supply. For first time, empirical relation linking animal characteristics riverbank is presented. The adds small number budget studies compare fluxes driven biotic abiotic energy but unique isolating measuring interactive effect facilitated activity. Biotic expended through represents surcharge system augment geophysical mechanisms.