Study on Species Composition of Zooplankton Communities in Warm Water Fish Ponds in Dezful

This research intended to study species composition of zooplankton in warm water fish ponds. Therefore, information about the structure and dynamics of zooplankton communities was collected from three fish ponds raising common carp together with Chinese carp (also called grass carp) in Dezful from late February 2014 to late September 2015. Zooplankton samples were taken from Ponds 1, 2, and 3 using 100μ mesh plankton nets. At each Station, 20 liters of water was filtered by the nets and poured into one-liter containers, the samples were fixed in 4% formalin and transferred to the laboratory, and the plankton was identified using valid identification keys. During the research, the physical and chemical parameters of the water in the Ponds (pH, concentrations of nitrate, phosphate, and ammonia, salinity, EC, hardness, dissolved oxygen, turbidity, and temperature) were measured to study their effects on the diversity and density of the phytoplankton. In pond 2, the maximum number of zooplankton (1313.38/l) was observed from late September to late October and the minimum (zero per liter) from late March to late April and from late April to late May. Among the identified species, Trichocera sp. had the largest number (6/l), the most frequently observed class (80.46%) were the Rotifers and the most frequently identified species Trichocera sp. In pond 1, the maximum number of zooplankton was counted from late August to late September and the minimum from late March to late April, and again the Rotifers with five species and 87.71% of the total population were the most often observed and, similar to Pond 2, the most frequently found species was Trichocera sp. In Pond 3, the largest number of zooplankton was counted from late May to late June and the smallest from late April to late May. As in the other two Ponds, the Rotifers with 70.27% of the total population and 5 species were the most often observed zooplankton, with the Brachionus sp. the most often identified class. No correlation was found between the identified zooplankton and the physical and chemical parameters of the water in the ponds.