Agricultural Research,Education and Extension Organization Iranian Journal of Fisheries Sciences 1562-2916 19 4 2020 07 01 The impact assessment of cage culture of rainbow trout (Oncorhynchus mykiss Walbaum, 1792) on benthic communities using biological indicators in the South Caspian Sea, Iran 2142 2158 117032 10.22092/ijfs.2018.117032 EN Kourosh HaddadiMoghaddam Department of Fisheries, Faculty of Agriculture and Natural Resources, Science and Research Branch, Islamic Azad University, Tehran, Iran. Mehdi Soltani Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran A Kamali Department of Fisheries, Faculty of Agriculture and Natural Resources, Science and Research Branch, Islamic Azad University, Tehran, Iran. H.A Abdolhay Iranian Fisheries Science Research Institute, Tehran, Iran, P.O.Box: 14155-6116 Journal Article 2017 04 19 In this study, the impact of cage culture of rainbow trout (Oncorhynchus mykiss Walbaum), on benthic communities using biological indicators located along the coastal areas of the South Caspian Sea (Nashtarudregion, Mazandaran Province, Iran) was investigated. Monthly samplings from 4 stations were carried out from January 2016 to May 2016.The physical and chemical characteristics of water were measured on a monthly basis. Sediment samples were taken using Ekman Grab. The ecological indicators such as Shannon–Wiener index of diversity, H, Simpson, S, and Margalef, R, was routinely used. The biomass-dominant faunal groups were Bivalve (146.16 g/m2 (,Crustacea (24.5 g/m2) and  Polychaeta (10.5 g/m2).The greatest variety of benthos was found under the cage and the lowest range was found150-300 m around the cage that was significantly difference (P<0.05). Results of current study showed that, the percentage of sand was greater than that of silt and clay throughout the experimental period. Sediment organic matter (OM%) reached extremely high concentrations beneath the control (P<0.05), when compared surrounding area. A positive correlation coefficient was found betweenthe Shannon–Wiener diversity index (H'), and biomass of benthic organisms (p=0.001; r= 0.684). According to results of species diversity, and amount of organic matter in the cage area, indicated that specific richness levels were in bad ecological statues. https://jifro.areeo.ac.ir/article_117032_00aac0a5b5ee41787c3edb50f681a568.pdf