North Carolina Bird Islands and Sanctuaries for the Future

Abstract

The Pine Island Sanctuary freshwater marsh has been eroding by 0.23 meters per year and from 2003-2016 has lost approximately 8 acres of marsh. The marsh, currently totaling 2,600 acres, is losing on average 0.8 acres/year, which translates into $1,815.54/yr of marsh property value loss, or $1,892.38/year including lost ecosystem services in 2018 dollars. I quantified lost ecosystem services including carbon sequestration, nitrogen mitigation, and the recreational value of duck hunting, calculating lost ecosystem service values using a transferred benefit model. The values used were derived from studies based on similar marsh conditions. For the area calculations, I used orthophotos and two geographic information system software extensions. Digital Shoreline Analysis System, DSAS, uses digitized shorelines over a period of time to calculate shoreline change statistics. The DSAS calculations served as a benchmark to compare to unsupervised iso-clustering calculations, which allowed me to determine an average rate of shoreline change throughout the marsh. The average difference between the two methods was 3cm/year and the max difference was 7cm/year. Looking ahead, marsh sills, living shorelines, and rip raps are some examples of erosion control that could be used to mitigate Pine Island’s erosion. If the cost of the erosion control measure is less than the current rate of erosion costs on a yearly basis, the Audubon Society should undergo the project.