Seasonal Trophy Assessment in Choghakhor Wetland Based on Zooplankton Communities

In this study, the status of trophy of Choghakhor wetland was investigated using zoopelanktons. Sampling was performed in 4 seasons and 10 stations since April 2010 to March 2011. Spacing between stations adjacent was considered 1km to each other. Zooplankton sampling was done horizontally (2m) using closing net with an aperture size of 55 microns at depth of 30 cm. Results showed that the most abundant family of zooplankton communities are rotifers (9 families and 16 genera), Branchiopoda (3 families and 5 genera) and copepods (1family and 3 genera). Rotifera was the most abundant taxon in all seasons. Abundant of keratella sp. in spring, Monostyla sp.in summer and autumn and Polyarthra sp. in winter were significantly more than the other species (P>0.05). And also Shannon and Simpson diversity indices in autumn, were significantly higher in comparison with other seasons (P>0.05). The highest level of chlorophyll in summer and fall were 20.92 and 22.63 mg per cubic meter respectively. The annual average of that in the wetlands was determined 75.18 mg per cubic meter, showing that the trophy of wetland was high. In addition, evaluation of trophy indices based on phosphate, nitrate and transparency parameters, demonstrated that trophic state of wetland was in eutrophic condition. Increases in Abundant of Polyathra, Brachionus, Monostyla, Keratella geniuses in this condition can be a sign of eutrophication happening in this wetland.