SHIFTING SHORELINES ON WOLF AND EGG ISLANDS, GEORGIA, USA: A STUDY OF CHANGE SINCE 1953

Barrier islands often protect back-barrier coastlines from harsh wave activity, erosion, and tidal surges. The Georgia barrier islands certainly fulfill this role, while also providing homes to a wide variety of birds, reptiles, and other wildlife. Of these, Wolf Island, a Holocene barrier island on the mouth of the Altamaha River, is one of the least-studied. This situation is at least in part because of its U.S. National Wildlife Refuge status, making it difficult for researchers to learn more about the island through field of study. In our study, Wolf Island was studied using remote sensing through aerial photographs from 1953, 1974, 1975, 1976, 2009, 2013, and 2015. We did a similar analysis for nearby Egg Island using a polygon shoreline for island-area calculations. Aerial photographs and National Agriculture Imagery Program (NAIP) images were collected and georeferenced in both analyses. For Egg Island, polygons were traced along the high-water mark, then total areas of polygons for each year were calculated and compared. In contrast, complex tidal channels of Wolf Island only allowed for linear measurements along its east coast. Differences in area between each year were calculated for each island to determine net erosion or accretion. Egg Island showed net accretion from 1953 to 1974, then a period of erosion from 1974 to 1977, followed by accretion from 1982 to 2015. Accretion was likely a result of its location adjacent to the mouth of the Altamaha River, where sediment supply is high. However, despite Wolf Island having the same sediment supply from the Altamaha River, it showed net erosion from 1974 through 2015. Sea-level rise, longshore drift, or a combination of these factors have contributed to this erosion. Applications of this research should aid in predicting habitat gains or losses for nesting shorebirds and sea turtles with continued sea level rise.