Investigation of the Caspian trophy in south coastal areas of Caspian Sea, A case study in Gilan province

The increase of organic and inorganic compounds in the river basin of the south coastal area of the Caspian Sea has been exacerbated by intensification of the Eutrophication process. In order to provide some useful data for planning of coastal management, the trophy of the chlorophyll a, total phosphorus and total nitrogen were determined. The result of measuring three limnologic parameters (chlorophyll a, total phosphorus and total nitrogen) for a period of 11 months, were entered into the geographic information system during the spring of 2013 to February 2014. By determining the position of ten stations in south coast of the Caspian Sea, in Gilan province, from Khosk-Rood to Astara, their trophy status in terms of chlorophyll a, total phosphate, total nitrogen, as well as TSI index were determined. Based on the results of this study, among the three effective factors of trophic in the studied areas, in winter, the highest correlation was found between total phosphorus and total nitrogen of 47%. The annual survey showed a correlation between phosphorus and total nitrogen of 87%, followed by correlation between chlorophyll a and nitrogen of 56%. The results showed that, 39 and 61 percent of south coastal areas in Gilan province were oligotrophic and mesotrophic, respectively. The normal curvecomparison of total phosphate based on OECD standards, indicated a trend in coastal change from oligotrophic to mesotrophic, which can be a threat to the region