This study was carried out at the southeast of the Caspian Sea on the shores of the Goharbaran region during 2013-2014. Sampling was repeated monthly in eight stations. A total of 157 species of phytoplankton, 10 species of zooplankton and 24 species from macro invertebrate were identified. There were significant differences based on abundance and biomass among different biological groups in various stations (p<0.05). Comparing the abundance and density of phytoplankton in different seasons showed that there was an increasing trend in phytoplankton from spring to winter, whereas the abundance and biomass of zooplankton showed a decreasing trend. The results of the multivariate statistical analysis, Pearson correlation coefficient and Principal Component Analysis (PCA) in different months showed that the biomass of phytoplankton and zooplankton had the highest correlation (0.943), whereas the abundance of zooplankton and jelly comb had the highest correlation which could be due to their physiological structure and ecobiological conditions. In conclusion, ecological relationships among biological groups can be due to the abundance and biomass changes, species diversity, environmental parameters, predator, seasonal changes, feeding habits and environmental pollutions.