Virginia Institute of Marine Science
Salt marshes are valued for their ecosystem services, and their vulnerability is typically assessed through biotic and abiotic measurements at individual points on the landscape. However, lateral erosion can lead to rapid marsh loss as marshes build vertically. Marsh sediment budgets represent a spatially integrated measure of competing constructive and destructive forces: a sediment surplus may result in vertical growth and/or lateral expansion, while a sediment deficit may result in drowning and/or lateral contraction. Here we show that sediment budgets of eight microtidal marsh complexes consistently scale with areal unvegetated/vegetated marsh ratios (UVVR) suggesting these metrics are broadly applicable indicators of microtidal marsh vulnerability. All sites are exhibiting a sediment deficit, with half the sites having projected lifespans of less than 350 years at current rates of sea-level rise and sediment availability. These results demonstrate that open-water conversion and sediment deficits are holistic and sensitive indicators of salt marsh vulnerability.
SEA-LEVEL RISE; TIDAL WETLAND STABILITY; SEDIMENT TRANSPORT; CONCEPTUAL-MODEL; RESILIENCE; ACCRETION; COLLAPSE; FLUX; BAY; VEGETATION
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This study was part of the Estuarine Physical Response to Storms project (GS2-2D), supported by the Department of the Interior Hurricane Sandy Recovery program and the U.S. Geological Survey Coastal and Marine Geology Program. M.L.K. acknowledges funding from NSF GLD 1529245, NSF Coastal SEES 1426981, NSF LTER 1237733, and the USGS Climate and Land Use Change Research and Development Program. S.F. acknowledges funding from NSF LTER 1237733, NSF LTER 1637630 and the Department of the Interior Hurricane Sandy Recovery program (project GS2-2D). Marinna Martini, Ellyn Montgomery, Jonathan Borden, Christine Sabens, Patrick Dickhudt, Sandra Brosnahan, Steven Suttles, Roland Hagan, Karen Thorne, Chase Freeman, Christopher Sherwood, Dan Nowacki, Patrick Brennand and Kyle Derby are acknowledged for assistance with this study. Namsoo Suk provided data for site SC. Erika Lentz and two anonymous reviewers provided constructive comments on the manuscript.
Ganju, Neil K.; Defne, Zafer; Kirwan, Matthew L.; Fagherazzi, Sergio; D'Alpaos, Andrea; and Carniello, Luca, Spatially integrative metrics reveal hidden vulnerability of microtidal salt marshes (2017). NATURE COMMUNICATIONS, 8.