Dr. Muriel Brückner (University of Exeter)

Biogeomorphic feedbacks between geomorphology and ecosystem engineering species, such as vegetation and benthic organisms, shape the evolution of our rivers and coastlines. Understanding how geomorphology changes over space and time is crucial for mitigating flood risk and sustaining human usage and biodiversity along rivers and coasts. To quantify how ecosystem engineering drives geomorphology and species patterns, I present a novel eco-morphodynamic model that couples detailed ecological and hydro-morphodynamic processes. The model illustrates the relevance of ecosystem engineering and species-specific traits for salt marsh establishment and expansion, and the capacity to drive mud layer accretion in dynamic estuaries, a relevant factor in stabilizing geomorphology and promoting species diversity. Similarly, biofilms stabilize existing mudflats which enhances mud at the scale of entire estuaries, whereas bioturbators can cause a loss of mud in tandem with estuary widening. Studying the effects of dam construction shows that geomorphic feedbacks in dynamic rivers can compensate for upstream sediment reduction and mitigate lack of sediment transport towards the downstream. Those findings underline the need to account for multiple organisms in hydro-morphodynamic models to predict responses to disturbances such as climate change and human impact. Leveraging positive effects of species communities can help us design appropriate restoration and flood protection measures in coastal Louisiana and elsewhere.