Study on biological status of the Gorgan Bay

Present study carried out between September 2011 and October 2012 in 19 sampling sites in order to investigate the trophy level, productivity, and natural dominant living conditions in the Gorgan Bay. According to the provided maps from the shoreline, depth, and sediment, the total area and volume of Gorgan Bay is 466 square meters and 905.33 million cubic meters respectively. Also the physic-chemical parameters including: water temperature, EC, salinity, transparency, DO, BOD_5, pH, Ammonia, Nitrate, Total hardness, Total alkalinity, and phosphate are determined and studies. 3 main phylum, 12 orders, 6 classes, and 12 families from bottom living organisms (macro-benthos) were identified in this region. Standard deviation in TSI was from minimum 37 in March up to maximum 65 in September and the annual average was 53. According to the average TSI in different months, for five months namely as March, April, June, August, and February the dominant situation was eutrophy. For the rest of months namely as May, September, October, November, December, and January the dominant situation was Meso-trophic in the Bay. Based on calculation, minimum and maximum productivity in the Bay were 92.26 and 700.66 Kg per hectare in October and July respectively. The annual average of productivity was 195.10 Kg per hectare