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Biogeochemical processes in land-ocean interfaces, surface estuaries, subterranean estuaries and sediment-water interface
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Marsh crab impacts on hydrology and biogeochemistry alter coastal carbon cycling
Monday 7th @ 1130-1150, Conference Room 1
Julia A. Guimond* , University of Delaware
Holly A. Michael, University of Delaware
Presenter Email: jguimond@udel.edu |
| Carbon sequestration in tidal marshes is a valuable carbon sink on the global scale, yet these ecosystems are threatened by climate change and anthropogenic influences. Large uncertainties in the present-day salt marsh carbon budget and mechanisms mediating the magnitude and direction of carbon fluxes limit the efficacy of conservation efforts, investment in tidal wetlands for long-term carbon storage, and our ability to predict carbon budget feedbacks with anthropogenic and climatic change. In an effort to mechanistically link ecosystem components and enhance future carbon budget predictions, we assess the interactions between crab activity, water movement, and biogeochemical conditions in a mid-Atlantic salt marsh. Field analyses show that crab burrows enhance vertical and horizontal carbon exports through physical and chemical changes. Burrows raise the permeability of the marsh platform in the summer by an order of magnitude, increasing horizontal exchange between the carbon-rich marsh and the creek. Burrow-enhanced vertical connections between surface and subsurface increase the depth of the oxic zone where carbon oxidation more readily occurs, reducing the capacity for marsh sequestration of organic carbon. Thus, we identify a positive feedback mechanism between crab activity and carbon efflux. On the global scale, we calculate that crab burrows are responsible for a 0.04-4.4% decline in salt marsh carbon burial, a number that could grow to 9% in the coming century. |
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