THE POTENTIAL RESILIENCY OF A CREATED TIDAL MARSH TO SEA LEVEL RISE

The purpose of this study was to determine the elevation dynamics of a created tidal marsh on the North Carolina coast. Deep rod surface elevation tables (RSET) and feldspar marker horizons (MH) were installed in plots to measure net surface elevation changes and to quantify contributing processes. Twelve total plots were placed on four elevation gradient transects (three transects within the created marsh and one within a reference marsh), with three plots along each transect. Elevation gradient transects included a low marsh plot dominated by Spartina alterniflora, a middle marsh plot dominated by Juncus roemerianus, and a high marsh plot dominated by Spartina patens. RSET and MH were measured in December 2012, January 2014, April 2017, and March 2018. Elevation change ranged from 1.0 to 4.0 mm year(-1) within the created marsh and from -0.4 to 2.0 mm year(-1) within the reference marsh. When compared to the long-term linear trend in local relative sea level rise (RSLR) of 3.10 +/- 0.35 mm year(-1), the middle marsh plots within the created marsh trended toward survival, with an observed elevation increase of 3.1 +/- 0.2 mm year(-1). Alternatively, the low and high marsh plots within the created marsh trended toward submergence, with observed elevation increases of 2.1 +/- 0.2 and 1.3 +/- 0.2 mm year(-1), respectively. These results indicate that a created marsh can display elevation dynamics similar to a natural marsh and can be resilient to current rates of RSLR if constructed with a high elevation capital. Surface elevation changes were observed over a short time period and in a relatively young marsh, so it is uncertain if these trends will continue or how the long-term relation with RSLR will develop. While this study provided initial data on the ability of created tidal marshes to respond to observed sea level rise, subsequent observations are needed to evaluate the long-term elevation dynamics.