Coastal wetlands are critical to the productivity and diversity of marine ecosystems and to the human economies they support. The Northeast and Mid-Atlantic regions of the US include thousands of coastal wetlands, with the shoreline characterized by salt marshes, tidal flats, beaches and dunes, and a wide variety of river deltas, sounds, inlets, and estuaries. Yet many coastal counties are experiencing significant population growth, and with estimates of sea level rise projected up to six feet by the next century, it is likely that many wetland habitats and their ecosystem services will be lost. The characteristics of some coastal wetlands make them more likely to be resilient and remain diverse and productive even as they adjust to climate-induced changes. In this project, we mapped these characteristics and estimated the relative resilience or vulnerability of 10,736 coastal sites from Maine to Virginia.Technical methods for mapping and estimating coastal resilience were developed in concert with a steering committee of 35 coastal experts that included members of the U.S. Fish and Wildlife Service (USFWS), representatives from the National Oceanic and Atmospheric Association (NOAA) and other federal, state and NGO staff from both Northeastern and Southeastern states. We divided the coast into 10,736 individual sites centered around each tidal marsh or complex of tidal habitats over two acres. For each site, we estimated the amount of migration space available under six sea-level rise scenarios and we identified the amount of buffer area surrounding the tidal complex. We then examined the physical properties and condition characteristics of the site using newly developed analyses as well as previously published and peer-reviewed datasets. For tidal complexes, the physical factors assessed included the size and tidal zone diversity of the migration space, the size and shoreline intricacy of the existing tidal complex, and the amount of shared edge between the tidal complex and its migration space. Condition factors included the amount of hardened shoreline, as well as the magnitude of nitrogen inputs, and the quantity of sediment and freshwater inputs. For the buffer area, we assessed its size and variety of compatible landforms and soils, the connectedness of its wetlands, and the amount of natural cover. A score was calculated for each site based 80% on the tidal complex and 20% on the buffer, with equal weight given to physical and condition characteristics. Scores were calculated for each of six sea-level rise scenarios (1 to 6 ft.). Our final maps were based on the 6-foot scenario because this scenario reveals the sites with the greatest long-term potential for adaptive response. We made the 6-foot results even more robust by slightly boosting or penalizing the score based on whether the size of the migration space showed a significant increasing or decreasing trend over the 3-6 foot scenarios.The scores are presented relative to other complexes within one of five coastal shoreline regions. Coastal shoreline regions are geographic areas where the coasts and estuaries are dominated by a common set of processes and geomorphology (e.g., drowned river valleys, lagoons, embayments). The scores are presented in standardized normalized values (z-scores), which are units of standard deviations above or below the mean score of all sites in the coastal shoreline region. For example, a z-score of 3 SD for a site in the lagoon shoreline region indicates that the site score is three standard deviations higher than the average score for all lagoon sites.Resilience Z-score, Condition Z-score, Physical Z-score and Shoreline units of the Northeast U.S. and Mid-Atlantic States. Ecosystem, population, ecoregional portfolio, restoration priorities, shoreline type, nitrogen levels, & sediment loads also portrayed.For more information see theResilient Coastal Sitesfor Conservation in the Northeast and Mid-Atlantic report
