Projections of Mangrove, Saltmarsh, and Oyster Reef Viability in the US East Coast and their Role in Coastal Defense

Abstract

This work aims to project the possible extent of mangrove forests, saltmarshes, and oyster reefs in the southeast and mid-Atlantic coasts of the United States (South Carolina, North Carolina, Virginia, and Maryland) through the end of the 21st century. These projections are based on several climatic scenarios ranging from minimum possible temperature increases (SSP1-2.6) and minimal sea level rise, through runaway anthropogenic climate change (SSP5-8.5) and up to 3 meters of sea level rise. Using these projections, I demonstrate that each of the analyzed eco-defenses can be used as part of a coastal defense plan.I began with a broad top down survey of the entire region. I created a series of viability maps for each eco-defense under all analyzed scenarios for the entire region. From here, I found the broad trends of possible defensive utility in the whole region. In general, mangroves’ ranges extend polewards as temperatures increase while saltmarsh and oyster reef ranges remain unchanged. Additionally, mangroves and saltmarshes suffer from coastal squeeze as sea levels rise. Next, I used a similar methodology to the top down approach to create higher resolution viability maps for a pair of case study cities, Newport News, Virginia and Charleston, South Carolina. This allowed for a detailed analysis of possible defensive strategies for the case study cities. Finally, I have created an optimization tool to compare the defensive utility of saltmarshes and mangroves under a wide array of initial conditions and assumptions. The goal here is to provide insights for a coastal community in crafting a coastal defense strategy based around eco-defenses, particularly where to focus when constrained by limited resources. Overall, this sequence of work provides a better understanding of the future and role of eco-defenses in the analyzed region at several scales. It also demonstrates a methodology that can be applied to other eco-defenses, on other coastlines, all across the world.