Does size matter? Quantifying the cumulative impact of small-scale living shoreline and oyster reef restoration projects on shoreline erosion

Shoreline erosion is a common problem for coastal systems, especially in areas of high human use. Small-scale living shoreline (LSL) and oyster reef restoration projects can potentially slow or reverse shoreline erosion in low-energy coastal environments. These projects are often easier and cheaper to implement when compared to hard armoring. However, their small size can also lead to limited funds for long-term monitoring and an underestimation of their impact on altering local erosion dynamics. Universal metrics are popular for monitoring the biological success of small-scale restoration projects, but may lack an affordable, easy method to quantify shoreline change over large spatial and temporal scales, including understanding losses prior to project initiation. Digital Shoreline Analysis System (DSAS) is a viable method to quantify cumulative shoreline change for multiple small-scale restoration projects in one ecosystem. For example, over the past 12 years, 89 oyster reef and 14 small-scale LSL restoration projects have occurred in Mosquito Lagoon, FL, U.S.A. While each project has been individually monitored, there has yet to be a combined quantification of the cumulative impact to shoreline erosion. Using imagery from USGS's Earthexplorer and the DSAS tool in ArcGIS, we calculated cumulative shoreline change impacts of small-scale restorations in one ecosystem. Both small-scale LSL and oyster reef restoration reversed shoreline erosion to accretion. Cumulative net shoreline gain for the LSL and oyster restoration projects were 347.62 m²/year and 288.91 m²/year, respectively. Quantifying cumulative shoreline change of multiple small-scale restoration projects is a beneficial addition to universal monitoring.