Conceptualizing the role of sediment in sustaining ecosystem services: Sediment-ecosystem regional assessment (SEcoRA)

There is a growing trend to include a consideration of ecosystem services, the benefits that people obtain from ecosystems, within decision frameworks. Not more than a decade ago, sediment management efforts were largely site-specific and held little attention except in terms of managing contaminant inputs and addressing sediments as a nuisance at commercial ports and harbors. Sediments figure extensively in the Millennium Ecosystem Assessment; however, contaminated sediment is not the dominant concern. Rather, the focus is on land and water use and management on the landscape scale, which can profoundly affect soil and sediment quality, quantity and fate. Habitat change and loss, due to changes in sediment inputs, whether reductions (resulting in the loss of beaches, storm protection, nutrient inputs, etc.) or increases (resulting in lake, reservoir and wetland infilling, coral reef smothering, etc.); eutrophication and reductions in nutrient inputs, and disturbance due to development and fishing practices are considered major drivers, with significant consequences for biodiversity and the provision and resilience of ecosystem functions and services. As a mobile connecting medium between various parts of the ecosystem via the hydrocycle, sediments both contaminated and uncontaminated, play both positive and negative roles in the viability and sustainability of social, economic, and ecological objectives. How these roles are interpreted depends upon whether sediment status (defined in terms of sediment quality, quantity, location and transport) is appropriate to the needs of a given endpoint; understanding and managing the dynamic interactions of sediment status on a diverse range of endpoints at the landscape or watershed scale should be the focus of sediment management. This paper seeks to provide a language and conceptual framework upon which sediment-ecosystem regional assessments (SEcoRAs) can be developed in support of that goal.