Homayoun Khoshravan - Caspian Sea National Research Center, Water Research Institute, Ministry of Energy, Tehran, Iran
Alireza Naqinezhad - Department of Biology, Faculty of Basic Sciences, University of Mazandaran, Babolsar, Mazandaran, Iran
Tahereh Alinejad-Tabrizi - Environment Research Management Group (EMRIRAN), Ministry of Science, Research and Technology, Unit ۵, Kaj Building, Shahid Amini Alley, Babol, Iran
Tamara Yanina - Faculty of Geography, Lomonosov Moscow State University, Moscow, Russia

The rapid Caspian Sea level fluctuations have caused unstable conditions for coastal areas during the ۲۰st and ۲۱st centuries, and have led to significant losses for economical and social infrastructure. The main objective of this study was to assess the impact of the Caspian Sea level fluctuations on the environment of the Gorgan Bay coasts, which is a large, shallow inlet at the extreme south-east corner of the Caspian Sea. So that, studying required documentations have made it possible to become acquainted with the geographical, geological and environmental conditions of Gorgan Bay. The morphological conditions of coastal lines and diversity of coastal habitats were also assessed in field observations. The geometric structure of coast, their sediment types and the physicochemical properties of soils belonging to coastal habitats were evaluated by determining three transects and nine study sites in the spring and summer ۲۰۱۷. Changes in the coastline of Gorgan Bay were also processed using Land-Sat satellite imagery from ۱۹۷۷, ۱۹۹۵ and ۲۰۱۷. The results exhibited that the environmental vulnerability of the Gorgan Bay coasts depends on the morphological conditions of coastal habitats and alterations in the Caspian Sea level. So that, the plant and animal communities located in the most end of western part of the Gorgan Bay have faced serious challenges during the current century due to the decrease in the Caspian Sea level. Connecting canals between the Bay and Sea will also lose their discharge capacity and the Gorgan Bay will completely be dried up due to this decline. Emergence of large mudflats with sedimentary composition of sandy silt, which has created a very good potential for occurrence of haze, and also replacing the drought ecosystem, instead of the aquatic one, are other environmental events which are expanding vastly in the coastal areas of the Gorgan Bay.

Caspian Sea, Coasts, Environment, Fluctuations, Gorgan Bay, Morphology