Sibila Maria Pando de Sousa Kretschmer

• Submarine canyons are giant topographic features that cut the continental shelves and slopes throughout the world‘s oceans. Submarine canyons are hotspots of biodiversity supporting large and diverse benthic and pelagic fauna communities attracted by the heterogeneity of different substrates. The faunal communities exhibit particular adaptations to the canyon characteristics under the influence of physical oceanographic processes, organic matter availability and sediment transport processes. The application of process-oriented numerical models has allowed an integrated approach to the simulation of spatial and temporal continuity that cannot be achieved by current analytical methods. Models facilitate the capability to bridge the gap between small and large scale processes, and this inherent property has made them an essential tool for understanding complex processes such as canyon dynamics and transport of particulate material and pollutants within. This work focused on the Nazaré submarine canyon, the largest submarine canyon on the Portuguese continental margin. Over the last decades several studies have addressed the hydrology, hydrodynamics, particle fluxes and food-web dynamics of this system This work attempted to better understand the dynamics of submarine canyons by a physically integrated modelling approach that utilized an in depth approach relative to previous works by adding to the model simulations of the canyon, more realistic boundary conditions, refined grid and lagrangian particle-transporting model. The 3D hydrodynamic model was forced by a regional operational model at the open boundaries and with the solution of an atmospheric forecast model at the surface, and validated using Argo floats and remote sensing data of the sea surface temperature (SST). Additionally, the transport of organo mineral aggregates (OMAs) and pollutants were simulated by coupling the hydrodynamic model with a lagrangian model. This approach brought forth new information on the transport and dispersion of the OMAs and pollutants within the Nazaré canyon.