In this study, the composition and abundance of phytoplankton and zooplankton in earthen ponds of Litopenaeus vannamei in Delvar, Bushehr were investigated. During the rearing period, the range of temperature changes and water salinity, dissolved oxygen and water clarity were 24-32 ° C, 45-50 g / l, 5.5-3.5 mg / l and 140-60 cm, respectively. The predominant genera of the phytoplankton community were Navicula, Cosinodiscus, Nitzchia, Rhizosolenia, and Pleurosigma from diatoms, Peridinium, Ceratium from dinoflagellates, Oscillatoria from cyanophytes, and Nannochloropsis from chlorophyta. Research on zooplankton has shown that their populations mainly include cephalopods, rotifers, polychaete larvae, sergestids and crustacean larvae. Paropods were the most abundant zooplankton community and the frequency range of Calanoidae, Cyclopoidae and Harpacticoidae was 3-17, 5-0.2, 0-1 individuals per liter, respectively. The Calanides were Acartia and Centropage, and the Cyclopides Oithona were predominant, with the only Harpticoid species being Euterpina. There were significant differences in the abundance of vultures and zooplankton in L. vannamei breeding period. Pearson correlation coefficients showed that the frequency of kalanide with soluble oxygen (r = -0.43) and salinity of water (r = -0.54) had a significant correlation and the frequency of cyclopeids with water temperature (r = 0.38) and pH (r = 0.32) It had a significant correlation. In general, the frequency of total zooplankton showed a significant correlation with dissolved oxygen (r = -0.39) and pH (r = 0.37). The results of principal factor analysis (PCA) showed that the frequency of rotifers, pH and total zooplankton as the first factor and salinity and dissolved oxygen as the second factor can be used to explain the most changes in the zooplankton community in Pafid shrimp ponds.
