Study of Monsoon affect to Zooplankton biodiversity in Chabahar eastern coasts (Makoran sea)

Zooplanktons have a special role in the food chain and the ecological pyramid of the marine ecosystem. The aim of this study was to investigate the effect of Monsoon on biodiversity of zooplanktons in the eastern coasts of Chabahar. Sampling was carried out on the eastern coast of Chabahar using a 100-micron zooplankton net with a horizontal extension stretch of 30 cm at 8 stations in the Chabahar bay during four seasons from summer of 2016 to spring of 2017. According to the results, Copepoda have rise to 66.87 percent of the zooplankton population. After the Copepoda, bivalvia (7.53%) and Thaliacea (6%) have highest presence and Polychaeta, Cephalochordata, Ostracoda were found to be the lowest (in total with 2.22%) in different sampling seasons. The highest and lowest Shannon index was calculated, respectively, in autumn (3) and spring (0.99), respectively, in the autumn and winter (0.95), and in summer and spring (0.94), respectively. The highest and lowest indexes of uniformity were in autumn and spring (0.97) and summer (0.94) respectively. According to the results of this research, the structure of the zooplankton communities in this region is affected by the changes caused by the monsoon winds and the coastal upwelling flows. The cycle of production and seasonal changes of zooplanktons depends on the environment response to these changes. Ultimately, when zooplankton organisms are exposed to severe disturbance (monsoon), several species become dominant and decrease the species uniformity.