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Paper No. 11
Presentation Time: 4:25 PM


WILSON, Kristin R.1, KELLEY, Joseph T.2 and BELKNAP, Daniel F.2, (1)Environmental Science, Allegheny College, Box E, 520 North Main St, Meadville, PA 16335, (2)Earth Sciences, University of Maine, Bryand Global Sciences, Orono, ME 04469-5790,

Salt marshes, including those in backbarrier settings, are vulnerable to rising sea level in response to climate change. Studies in the Gulf of Mexico and Mid-Atlantic regions suggest that one response of salt marshes to sea-level rise is an irreversible state change through the expansion of pools in interior marsh sections, leading to the rapid conversion of once-vegetated surfaces to open water over short time periods. In Maine’s meso-macro-tidal marshes (tidal range 2-6 m), previous work shows that a dynamic exchange between pools and tidal creeks is one mechanism that reverses this process at the local scale through pool drainage and subsequent revegetation. Lead-210 and 137Cs dating of sediments in two paired cores collected through revegetated pools and adjacent high-marsh surfaces from Wells and Brunswick, ME, indicate that revegetated pools rapidly accumulate sediment at 2-4.5 times the rate of the neighboring marsh platform. This result is consistent with other modeling results that predict that disturbed, recently revegetated salt-marsh patches accrete faster than undisturbed vegetated patches. Our results have important implications for the overall sediment budget of salt-marsh systems, especially in the northeast where pools are prominent features, and for the capacity of these systems to sustain themselves in response to rising sea level. With accelerated sea-level rise, two predicted system-level responses are an increase in the tidal prism and channel deepening, both of which will increase the hydraulic potential between pools perched on the salt-marsh platform and deepened tidal creeks, in places like Maine. In a system with a limited or finite sediment supply, pools may then capture a disproportionate amount of the sediment load available to the marsh surface. This, in turn, may starve other portions of the marsh platform from receiving this load, creating a positive feedback system where pools drive surficial marsh dynamics and the marsh platform is unable to sustain itself over the long-term.
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