Estuaries on the Edge: Sediment Dynamics and Resiliency of U.S. Pacific Coast Wetlands

Although geographically small, the estuaries of the U.S. Pacific coast play an outsize role in the economic, cultural, and ecological health of the region. Squeezed into a narrow elevation zone, coastal wetlands in this area are particularly threatened by land use and climate changes. Using a combination of sediment core analysis, short-lived radionuclides (beryllium-7, thorium-234), and time-series data (turbidity, salinity, discharge), we examine seasonal- and event-scale sediment dynamics in the Coos estuary (Oregon) to assess the resiliency of the ecosystem. We link our field-based observations to the results of an existing model-based sediment dynamics simulation and compare the sustainability of wetlands impacted by dredging and land reclamation with those protected as part of the South Slough National Estuarine Research Reserve, which lies entirely within the greater Coos estuary. We focus in particular on native oyster and eelgrass beds, critical habitats where recent restoration efforts have yielded mixed results. Our analysis informs restoration and ecosystem management in support of a healthy, productive, and resilient coastal landscape.