The impact of Asian sea bass) Lates calcarifer) cages culture on the population structure of phytoplankton, eutrophication status and risk of eutrophication in the coastal waters of Qeshm Island, Hormozgan province

In this study, the possible impact Asian sea bass fish (Lates calcarifer) cages culture on the population structure of phytoplankton in the coastal waters of Qeshm Island.Water sampling was done monthly for a period of six months in three stations from October 2018 to March 2019.The results showed that the mean Variations of total abundance of phytoplankton at the location of fish cages culture compared to the Reference station had a significant increase (P <0.05). At the location of cages culture, the Trophic status level was high (<5), the risk of eutrophication status (<4) and the value of trophic efficiency coefficient were high. According to the analysis of Simper test, Among the Forty-one genera identified, Noctiluca sp. with a relative abundance of % 82.37, contribution rate of 21.8% with high algal bloom at the location of cages in autumn season and then the genera Chaetoceros sp., Nitzschia sp. and Coclodinium sp. with a relative abundance of less than 10 percent in differentiating the population structure of phytoplankton have played a significant role in the dissimilarity of the population structure of phytoplankton between stations In general, in this study, the effects of fish farming activities on the population structure of phytoplankton are ineffective, but it causes the abundance of some species, available nutrients, increases the trophic level, and the probability of harmful algal blooms in the location of the cages culture.