A non-linear relationship between marsh size and sediment trapping capacity compromises salt marshes’ resilience to sea-level rise

Geology
By: , and 

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Abstract

Global assessments predict the impact of sea-level rise on salt marshes with present-day levels of sediment supply from rivers and the coastal ocean. However, these assessments do not consider that variations in marsh extent and the related reconfiguration of intertidal area affect local sediment dynamics, ultimately controlling the fate of the marshes themselves. We conducted a meta-analysis of six bays along the United States East Coast to show that a reduction in the current salt marsh area decreases the sediment availability in estuarine systems through changes in regional-scale hydrodynamics. This positive feedback between marsh disappearance and the ability of coastal bays to retain sediments reduces the trapping capacity of the whole tidal system and jeopardizes the survival of the remaining marshes. We show that on marsh platforms, the sediment deposition per unit area decreases exponentially with marsh loss. Marsh erosion enlarges tidal prism values and enhances the tendency toward ebb dominance, thus decreasing the overall sediment availability of the system. Our findings highlight that marsh deterioration reduces the sediment stock in back-barrier basins and therefore compromises the resilience of salt marshes.

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Publication type Article
Publication Subtype Journal Article
Title A non-linear relationship between marsh size and sediment trapping capacity compromises salt marshes’ resilience to sea-level rise
Series title Geology
DOI 10.1130/G47131.1
Volume 48
Issue 10
Year Published 2020
Language English
Publisher Geological Society of America
Contributing office(s) Woods Hole Coastal and Marine Science Center
Description 5 p.
First page 966
Last page 970
Country United States
State Massachusetts, New York, New Jersey, Maryland, Virginia
Other Geospatial Plum Island Sound, Great South Bay, Jamaica Bay, Barnegat Bay–Little Egg Harbor, Chincoteague Bay, Virginia Coast Reserve
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