An assessment of salt marsh vulnerability & restoration potential in the Northeastern United States using physical and ecological indicators

With climate change and increased coastal land alteration, salt marshes globally are becoming increasingly degraded. Salt marshes of the Northeastern United States (Maine to Virginia) are particularly vulnerable given the history of intensive alteration such as ditching and tidal restrictions since European colonization. Such alterations reduce the accretionary potential of salt marshes in this region, in turn reducing their ability to keep up with accelerating relative sea level rise. This ultimately leads to reductions in marsh area and loss of ecosystem function, including flood protection, carbon burial, habitat provision, and nutrient filtration. Through collaboration between multiple government, academic, and non-profit organizations, we investigate the following questions: (1) What are the spatial patterns of salt marsh vulnerability to relative sea level rise across the Northeast United States? (2) Additionally, how is this vulnerability linked to specific salt marsh modifications (e.g., ditching, and tidal restrictions)? To address these questions, we combine the Unvegetated to Vegetated Ratio (UVVR) salt marsh vulnerability metric, computed from 2014-2018 using Landsat imagery, with mapped tidal restrictions (e.g., culverts, bridges, tide gates, dikes) and ditches for the Northeastern coast of the United States. We hypothesize that estimated salt marsh lifespans, a mass balance between relative sea level rise and sediment budget (estimated using UVVR), will be shortened where salt marsh modifications are most intense. Results will be used to drive science-based decision making through prioritization of salt marsh restoration.