The investigator will complete work in this third year of a continuing project that addresses the problem of salt marsh dieback, which leads to the loss of key economic and ecological services that are normally provided by marshes. The exact cause of dieback is unknown, but dieback in the Southeast is clearly associated with drought. This work will provide a critical first step for understanding marsh dieback by determining how drought affects soil moisture and salinity in a marsh and how hydrologic changes propagate to the marsh plants.
The objectives of this project will be to (1) determine how normal climate variability affects salt marsh dynamics (hydrology and ecological productivity), (2) reconstruct groundwater conditions during the 1998-2002 drought, when large-scale marsh dieback occurred, (3) test the hypothesis that differences in the ‘plumbing’ within a marsh island caused one area to be affected by marsh dieback while the rest remained healthy during the drought, (4) test the hypothesis that drought can cause rapid changes in soil moisture and salinity to determine if dieback may be caused not by extremes in marsh conditions but by rapid changes in marsh conditions, and (5) test the hypothesis that groundwater withdrawal (pumping) could cause hydrologic changes similar to those during a drought, thereby contributing to marsh dieback.