Informing Thin-Layer Placement for Coastal Wetland Restoration Through Remote Sensing and Community Outreach

Due to multiple anthropogenic drivers, coastal wetlands have lost roughly 50% of their historical coverage, and deterioration is accelerating with rising sea levels. Thin-layer placement (TLP), the spreading of sediment dredged from nearby water bodies across existing wetlands or shallow mudflats to raise surface elevation, has emerged as a viable approach to sustain and restore these habitats. Strategies for the prioritization of site selection and design elements for TLP interventions remain unclear; a gap that must be closed to coordinate dredging with wetland restoration efficiently, given time, financial, and sediment constraints. Here, we present a transferable workflow to plan TLP projects, including systematic assessment of restoration needs, development of sediment application options, and prioritization of project sites that leverage publicly available remote-sensing data products and stakeholder input. We demonstrate its applicability in a rapidly deteriorating salt marsh–mangrove co-dominated system on the Atlantic coast of Florida. Guided by stakeholder priorities for storm-surge mitigation and habitat improvement, we tracked long-term (1952–2023) changes in vegetated wetland coverage to quantify loss trends and establish historic habitat borders as restoration targets. We then summarized short-term (2010–2023) habitat-mosaic shifts to resolve plant-species composition changes. In our focal system, long-term analyses revealed hotspots (zones 1 and 7) of >35% vegetation loss, while short-term analyses showed a 180% mangrove expansion and cordgrass degradation across all zones, suggesting a nuanced, tailored approach to sediment application. Taken together, this workflow provides a data-driven, stakeholder-informed process for TLP site prioritization to restore threatened wetlands, bolster coastal resilience, and maximize stakeholder benefits in our demonstration system in northeast Florida and, more broadly, to other dynamic coastlines.