SALT MARSH VULNERABILITIES TO SEA LEVEL RISE: LINKING ASSESSMENT TO ADAPTATION IN THE DELAWARE ESTUARY.
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The loss of coastal wetlands and their ecosystem services has been a particularly serious problem in the Delaware Estuary. For salt marshes, decreases due to erosion, nutrient enrichment, and hydrological alterations are being exacerbated and accelerated by ongoing sea level rise (SLR). Given these impacts, it is important for managers to account for SLR in adaptation planning. Yet it remains a challenge to frame SLR vulnerability in a way that facilitates direct linkages to specific management actions, thereby allowing more rigorous adaptation design. To this end, we used a relative wetland vulnerabilities framework which provides a step-by-step process that distinguishes the main components of vulnerability so that varying exposures and sensitivities can be understood and addressed in a more targeted way. Because the concept of vulnerability depends on what ecosystem service/management objective is at play, we not only assessed changes in total salt marsh habitat, but also broke salt marshes into high marsh and low marsh zones. We then explored vulnerabilities in the context of three different management examples, centered on preservation of: (1) saltmarsh sparrow nesting habitat (high marsh), (2) blue crab nursery habitat (low marsh), and (3) flood protection (total marsh). Through these examples, we illustrate how an attribute of interest (e.g., salt marsh extent) drives the vulnerability assessment process in a fashion that generates different concepts of vulnerability depending on the specific management objective. We then link the results to specific management programs and activities of the Partnership for the Delaware Estuary, with ideas for climate-smart adaptations.