The study on diatoms in the estuary of the major rivers of the Caspian Sea (Iran waters)

This study aimed to identify and recognize the changes and the temporal and spatial dynamics of diatom communities in the Southern Caspian Sea, in the Southern Caspian Sea, in 2010- 2011 during spring, summer, autumn and winter, in 32 study sites from 8 transects Astara, Anzali, Sefidrood, Tonekabon, Noshahr, Babolsar, Amirabad, Turkaman and the south coast of the Caspian Sea. In each transect, have choosen 5 stations and different depths of 5 m, 10 m, 20 m, 50 m and 100 m were determined sampling was done seasonally from zero depth (level) and 10 m, 20 m, 50 m and 100 m depth by Niskin sampler. A total of 87 species belong to diatoms. Most species of diatoms was seen in autumn (64 species) and then in spring (48 species). The dominant species include Pseudonitzschia seriata¡ Rhizosolenia fragilissima, Stephanodiscos sp., Melosira varians ¡Nitzschia acicularis, Cyclotella menenghiniana. The highest species diversity was in the spring and then gradually in summer, autumn and winter decreased due to Shannon index in the spring in the western region (0.96) and minimum Shannon index was seen in autumn in western region (0.47).