Coastal wetlands benefit human health and well-being through services such as shoreline protection, carbon sequestration, flood mitigation, seafood, recreational opportunities, and fish and wildlife habitat. In the coming century, accelerated sea-level rise will serve as a major stressor on the distribution and extent of coastal wetlands. Upslope, landward migration is one mechanism that allows coastal wetlands to adapt to rising sea levels. However, due to differences in topography and coastal urbanization, estuaries vary in their ability to accommodate migration. Low-lying urban areas can prevent migration, resulting in wetland loss where existing wetlands cannot keep pace with rising seas via vertical adjustments (i.e., coastal squeeze). Migration corridors are particularly important in highly urbanized estuaries where, due to low-lying coastal development, wetlands lack the space to move inland to adapt to sea-level rise. For future management of coastal resources, it is imperative to identify landward migration corridors and better quantify the potential for migration and coastal squeeze. For 39 estuaries along the U.S. Gulf of Mexico coast, we quantified and compared the area available for landward migration of tidal saline wetlands and the area where urban development may prevent predicted migration, under three sea-level rise scenarios (0.5-, 1.0-, and 1.5-m by 2100).
Results/Conclusions
In this region, the potential for wetland migration is highest within certain low-slope estuaries in Louisiana (e.g., Atchafalaya/Vermilion Bays, Mermentau River, and Barataria Bay) and southern Florida (e.g., the North and South Ten Thousand Islands estuaries). The potential for coastal squeeze is highest in estuaries containing major metropolitan areas that extend into low-lying lands. The Charlotte Harbor, Tampa Bay, and Crystal-Pithlachascotee estuaries (Florida) have the highest amount of urban land that is expected to constrain wetland migration. Urban barriers to migration are also high in the Galveston Bay (Texas) and Atchafalaya/Vermilion Bays (Louisiana) estuaries. As the rate of sea-level rise accelerates in response to climate change, coastal wetland ecosystem goods and services could be lost in areas that lack space for landward migration. The results from this study can assist conservation planners with developing future-focused landscape conservation plans that incorporate the protection of wetland migration corridors. This type of planning is critical to increase the adaptive capacity of these valuable ecosystems and simultaneously decrease the vulnerability of coastal human communities to the harmful effects of rising seas.