Tidal flats are under great pressure from human actions, especially activities in the catchments that feed the flats. Increases in nutrient loads, sedimentation and changed water flows are the primary stressors. The project will be the first to address how catchment processes affect distributions of seagrasses, which have contracted greatly in recent decades. The work will be a combination of (i) determining the factors that control seagrass distributions and the feedbacks that prevent re-establishment, (ii) understanding the role of seagrasses in carbon and nutrients dynamics, and (iii) building coupled hydrodynamic-biogeochemical models; these will allow the exploration of management options and to inform best practice management.