Study on trophic level of Gorgan bay

This study was conducted to assess the state of trophy, production capability, and identify the natural conditions at 19 stations of Gorgan Bay, between March 2015 and Febreuary 2016. According to the prepared maps of depths and bed, the current level and volume of Gorgan Bay were 466 km2 and 905.33 million m3 , respectively. To determine the trophy's condition, total phosphate and inorganic nitrogen were measured. The range of total phsphate changes varies from at least 37 in March to a maximum of 65 in April with the annual average of 53. The mean value of inorganic nitrogen was 16 µM. The trophic state based on the mean of total phosphate and inorganic nitrogen determined at Eutrophic and meso-eutrophic classes respectively. Therefore controlling and magement program of basin area is nessesary to increase shifting time of mesotrophic to eutroph/ hypertrophic condition of the Gorgan bay.