Hydro-eco-morphodynamics and carbon cycling at coastal scales and beyond

Morphological change of coastal and shelf seas is controlled jointly by physical, biological and anthropogenic processes and their interactions. While physical and anthropogenic drivers are normally regarded to exert a primary control on morphodynamics, the role of biota, especially benthos, in guiding long-term and large-scale evolution of coastal landscape/seascape is often overlooked and has received less attention. It was not until recent decades that research has revealed the importance of benthos in coastal protection. Further, as an indispensable part of the ecosystem, benthos not only consists of a significant part of organic carbon, but also plays a vital role in mediating carbon and nutrient fluxes across the sediment-water interface. The interaction between benthos and its ambient environment is twofold and dynamic. On one hand, coastal morphology, oceanographic forcing (e.g. tides, waves) and carbon/nutrient availability exert a first-order control on the type of habitats, as well as abundance and trait expression of benthos. On the other hand, benthos actively modifies its habitats and beyond to attain an optimized fitness for living conditions. Understanding such dynamic interactions is essential in management of coasts and shelf seas against present and future climatic threats and for sustainable use of coastal resources.

In this talk, we demonstrate the quantitative importance of fluid-sediment-benthos interactions in (1) guiding morphological development of a tidal embayment in the Wadden Sea and (2) carbon cycling in the great North Sea as exemplary case studies. We applied a novel 3-Dimensional physics-ecosystem coupled numerical model to resolve dynamic interactions among fluid forcing, organic carbon, sediment and benthos. Specifically, we aim to address two different but interrelated questions:

• How important are fluid-sediment-benthos interactions in coastal morphological development? and
• To what extent can such interactions affect carbon sequestration at a regional scale?