Does geomorphology determine vulnerability of mangrove coasts to sea-level rise?

By: , and 



The greatest climate-based threat to coastlines worldwide is sea-level rise. We tested the hypothesis that tropical coasts fringed by mangroves and receiving high inputs of terrigenous sediment are less vulnerable to sea-level rise than biogenic systems dependent upon peat formation for vertical land development. An analysis of published data spanning a range of geomorphic settings showed that mineral accretion was a poor predictor of vulnerability to rising sea level. We additionally compared two oceanic island systems representing two extremes along this sediment gradient to further examine controls on elevation dynamics in minerogenic versus biogenic mangrove systems. Minerogenic systems characterized by intermediate to high rates of mineral sedimentation (Pacific high islands in Micronesia) were not better buffered against sea-level rise because of high subsidence rates. Peat-forming systems (Caribbean low islands in Belize) kept pace with relative sea-level rise (combined ocean and land movements) because of subsurface expansion driven by root matter accumulation. The data were not consistent with the paradigm that tropical coastlines characterized by peat-forming mangroves are generally more vulnerable to sea-level rise compared to minerogenic systems; however, they are not necessarily equally sensitive to the same external and internal forces controlling soil elevations. Our findings demonstrate that reliance on surface accretion data alone can lead to an inaccurate evaluation of coastal vulnerability and why all surface and subsurface land movements must be considered in relation to local sea-level trends to assess risk of submergence. Recognition of such differences is essential to proper management of tropical coastlines to ensure their resilience in the face of future sea-level rise.

Publication type Book chapter
Publication Subtype Book Chapter
Title Does geomorphology determine vulnerability of mangrove coasts to sea-level rise?
Chapter 11
DOI 10.1016/B978-0-12-816437-2.00005-7
Year Published 2021
Language English
Publisher Elsevier
Contributing office(s) Patuxent Wildlife Research Center, Wetland and Aquatic Research Center
Description 18 p.
Larger Work Type Book
Larger Work Subtype Monograph
Larger Work Title Dynamic Sedimentary Environments of Mangrove Coasts
First page 255
Last page 272
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