Saltmarsh Loss in Southeastern North Carolina Lagoons:Importance of Sea Level Rise and Inlet Dredging

Courtney T Hackney, William J. Cleary

Abstract


Salt marshes can maintain themselves during periods of relative sea level (RSL) rise through accumulation of autochthonous plant biomass and by capturing sediments. Lagoonal salt marshes in southeastern North Carolina accumulate 358 g m2yr-1 of roots and rhizomes within their sediments. At an average bulk density of 0.3 g cm-3 the marsh can vertically accrete 1.2 mm yr-1. The average RSL rise for the past 40 years was 1.9mm yr-l, thus these salt marshes cannot maintain themselves through autochthonous production alone. Large quantities of sand are available to these marshes through inlets and historical data show that marshes disappeared when this sediment source was eliminated. The predicted increase in the rate of RSL and the removal of large quantities of sand for beach renourishment on developed barrier islands may significantly hasten the drowning and disappearance of large areas of salt marsh in the lagoons of southeastern North Carolina.


Keywords


Adverse impact; dredging, salt marsh; sea level wetlands

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