Within this century, accelerated sea-level rise and coastal development are expected to greatly alter coastal landscapes across the globe. The future of mangrove forests, salt marshes, and salt flats (i.e., tidal saline wetlands, collectively) is uncertain, and coastal environmental managers are increasingly challenged to develop conservation strategies that will increase the resilience of these valuable ecosystems. One strategy for preparing for the effects of sea-level rise is to ensure that there is space available for tidal saline wetlands to adapt to sea-level rise. Here we used alternative future sea-level rise and urbanization scenarios to show where tidal saline wetlands may adapt via landward migration, where barriers may prevent landward migration, and how existing protected lands might accommodate expected landward migration. Our analyses span five U.S. gulf coast states (TX, LA, MS, AL, and FL). We evaluated three sea-level rise scenarios and a business-as-usual future urbanization scenario.
Results/Conclusions
At the region level, our analyses show that there is a massive amount of land along the U.S. Gulf of Mexico coast that is available for the landward migration of tidal saline wetlands. These areas consist of upslope and upriver ecosystems that are vulnerable to sea-level rise-induced ecological regime shifts. The county-level analyses show that much of the migration is expected to be concentrated along certain coastlines (e.g., Collier, Monroe, and Miami-Dade counties in Florida; Assumption, Cameron, Lafourche, Terrebonne, St. Mary, and Vermilion parishes in Louisiana). Topographic constraints are expected to limit the extent of landward migration along some coastal reaches. Migration barriers due to current and future urban development are expected to be highest in Florida, especially along the coastline that extends from Tampa to Fort Meyers. Although Louisiana is expected to experience the most landward migration of any state, much of the migration is expected to occur on unprotected lands (i.e., lands not owned by federal, state, local, or private institutions with the capacity for continued conservation). In contrast, much of the anticipated landward migration in south Florida is expected to occur on protected lands. Collectively, our analyses provide information that can be used to identify migration corridors and develop future-focused adaptation strategies that will improve the potential that the ecosystem goods and services provided by tidal saline wetlands will continue to be available for future generations.