The impact of bioturbation on seascape evolution

The biological imprint on seascapes and its importance relative to purely physical processes remains poorly understood. Biogenic mixing of surface sediments is pervasive in marine environments, and by modifying sediment distribution and renewing the seabed it potentially affects the rates of reworking and downslope transport of sediment by physical processes on continental margins. However, can bioturbation leave a recognizable signature on seascapes, and if so, under what conditions? Here I explore this possibility through numerical experiments with the sediment transport model SedFlux. Using well-known river systems as a starting point (e.g., Po River), and imposing different physical forcing regimes (in terms of sediment flux, storm energy, slope failures), the model predicts seascape evolution under ever-changing boundary conditions. Bioturbation interacts with other processes through the evolving seafloor sediment distribution, where physical reworking is dominated by rare, high-energy events (floods, storms, failures). I illustrate possible quantitative criteria for describing the effect of bioturbation on sedimentary processes, stratigraphy and seascape evolution. Finally, I discuss some of the model limitations and future challenges.