Ecology

Marsh Basin Dynamics

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Science  05 Apr 2013:
Vol. 340, Issue 6128, pp. 11
DOI: 10.1126/science.340.6128.11-a
CREDIT: © INGO ARNDT/MINDEN PICTURES/CORBIS

Coastal salt marshes—found at temperate and high latitudes—form on tidal flats. Such marshes are both ecologically important and highly biologically productive. Although often protected, their fragile nature and location make them particularly vulnerable to human activities and climate change. Mariotti and Fagherazzi analyze marsh basins—rounded tidal flats surrounded by salt marshes—at three sites on the U.S. Atlantic coast, as enlargement of marsh basins can drive marsh loss. They develop a simple dynamic model for the morphological evolution of marsh basins and show that the model has a single unstable equilibrium point for basin size. Below this size, basins shrink, and above it, they continuously enlarge. Aerial photos taken 50 years apart at the three locations reveal that for particular basin locations, the marsh boundary will grow and the basin will shrink, whereas at other locations, all basins are shrinking. The model suggests that sediment supply is the primary controlling factor for marsh boundary growth or recession, and historical data from the three locations, where river dredging has in some cases significantly influenced sediment supply, support this idea.

Proc. Natl. Acad. Sci. U.S.A. 110, 10.1073/pnas.1219600110 (2013).

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