Crayfish ecosystem engineering effects on riverbed disturbance and topography are mediated by size and behavior

AbstractAnimals that burrow, forage, or produce physical structures can have substantial impacts on transport processes related to erosion. However, the influence of behavior and body size on regulating the magnitude of engineering effects by animals is not well understood. For example, crayfish are common and abundant freshwater organisms that disturb sediments in ways that influence gravel transport, fine sediment suspension, and bank stability. Animals such as crayfish also display complex territorial and aggressive behaviors, often related to body size, which might influence their ability to influence sediment transport dynamics. We conducted an experiment with spiny-cheek crayfish (Faxonius limosus) to investigate the influence of behavior and body size on substrate disturbance. The experiment included 4 enclosure (0.31-m long × 0.21-m wide × 0.17-m deep) treatments that differed in the body size of individual crayfish and the amount of biomass: 1) 2 small young-of-the-year (YOY) crayfish of 15-mm ca...