Mangrove Presence is Associated with Lower Rates of Coastal Wetland Loss at Marsh-Mangrove Ecotone

Abstract

Coastal wetland area has declined globally over the last century, but the magnitude of loss rates varies widely, and the drivers of spatial variability in land loss are often unclear. To examine drivers of wetland loss in northeast Florida USA, we performed a land cover change detection analysis using Sentinel-2 satellite imagery and examined the roles of distance to shore, mangrove presence, and boat wake energy on marsh-to-water conversions. Between 2018 and 2024, 0.290 km 2 or 1.9% of total salt marsh and 0.007 km 2 or 0.1% of mangroves were converted to water. In this section of the Guana Tolomato Matanzas National Estuarine Research Reserve, 3.9 km 2 of land was converted from marsh in 2018 to mangrove in 2024. The largest conversion rates of marsh-to-water and mangrove-to-water (e.g., erosion or submergence) occurred within 20 m of the shoreline (23.2% of marsh in that area). Wetlands with a greater distance from shore and those with higher mangrove abundance had reduced wetland loss. We found that marsh loss is highly correlated with boat wake energy and that mangrove-dominated areas resist erosion in response to even the highest boat wake energy measured. Our findings suggest that coastal wetlands with mangroves in this region are less vulnerable to loss than those dominated by salt marsh vegetation. Our work may inform the land loss patterns of other coastal regions where mangroves are expanding.

Bibliographic Information