Changes in the structure of Bacillariophyta branch around the sea cage for fish farming located in the south of the Caspian Sea Nowshahr

Bacillariophyta are single-cehhed microalgae of various types, the developments of Bacillariophyta in ecosystems is influenced by several factors, including the increase and change of a specific resistant substance, changes in water quality and climatic conditions. In this study, the waters around the cage and also before and after the fish farming period in the cage were sampled and identified based on the proposed methods. Fish breeding cages are located in the southern basin of the Caspian Sea at a depth of 30 meters from the sea shore. North east, south and west of the cage were sampled from surface depth, middle and depth (30m). In total, a total of 40 species from 21 genera of Bacillariophyta were identified during the sampling period during the four periods. Before the breeding period, 22 species and at the beginning of breeding activities, 24 species of Bacillariophyta were identified. The highest density of Bacillariophyta was in the pre-breeding period and the highest density was observed in the western region (9747±1562×104 per cubic meters).