Coastal geology of Iztuzu Spit (Dalyan, Muğla, SW Turkey)

Abstract

This study was carried out in İztuzu Spit (IS, Muğla-SW Turkey), which is a special environmental protection zone due to the presence of a loggerhead turtle breeding area. The aims of this study are: (1) to determine surface sediment content, (2) to investigate the İztuzu Spit spatial changes using Google-earth images, and (3) to figure out the controlling factors in the spit development. The main shore of the İztuzu Spit is predominantly composed of medium-grained sands that contain dominantly ophiolitic rock fragments. Five types of ostracods, sixteen types of benthic foraminifera, gastropods, mollusc, and bivalve shell fragments were identified from the sediment sample taken from coastal part of the IS. The main coastal area of the İztuzu Spit attached to mainland initially decreased from 67.4 ha (2004) to 56.8 ha (2013) then increased to 58.5 ha in 2016. Significant erosion of the main beach of İztuzu Spit was observed in the north-western edge. A small coastal region separated from the İztuzu Spit by the Dalyan river mouth shows significant change. The northern side of this region acted as a new sedimentation area, while the southern side was affected by erosion. The reason of these changes is variation in the flow direction of the Dalyan River mouth due to the building of piers in the lagoon side of the İztuzu Spit. The main coastal part of the İztuzu Spit has recently been under the effect of waves, tides, and summer tourism clients, while the river flow direction and anthropogenic effects are the main controlling mechanisms in the development of the NW edge. Therefore, the İztuzu Spit must be monitored continuously and protected as this region is the breeding zone of the loggerhead turtle.