HR: 15:45h
AN: H43A-08    [Abstracts]
TI: Rainfall Erosion of Intertidal Wetlands
AU: * Torres, R
EM: torres@geol.sc.edu
AF: University of South Carolina, Department of Geological Sciences 701 Sumter Street, EWS617, Columbia, SC 29208, United States
AB: A poorly quantified and mechanistically overlooked material cycling process in estuarine landscapes is rainfall- driven erosion of intertidal salt marsh and mudflat surfaces. During low tide rainsplash erosion and runoff may entrain carbon-rich sediment that, due to high cohesion, ordinarily is not mobilized by tidal currents and shallow water waves (e.g., a deachment limited landscape). Consequently, low tide rainfall may affect tidal creek network structure, creek network extension and nutrient cycling. Field manipulations and passive observations show that low tide rainfall events preferentially entrain highly nutritious intramarsh particulate matter, and in some cases with high concentrations of adsorbed metals. Once mobilized, the subtle topographic variations of the salt marsh landscape route runoff and the suspended load to intertidal creeks, and the subtidal water column. Hence low tide rainfall-runoff processes may enhance the cycling of, for example, benthic microalgae and their products, a primary carbon source for estuarine food webs. Once in the subtidal zone the material may be exported to the coastal ocean or it may be redeposited on the marsh surface with the next high tide, depending on tidal phase. Taken together these observations reveal one facet of salt marsh interactions between landscape structure- biological processes-physical processes.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0422 Bio-optics
DE: 0428 Carbon cycling (4806)
DE: 1815 Erosion
DE: 1845 Limnology (0458, 4239, 4942)
SC: Hydrology [H]
MN: 2007 Joint Assembly