Composition and Abundance of Phytoplankton and Zooplankton from Earthen White Leg (Litopenaeus vannamei) Shrimp Ponds

In this research, composition and abundance of phytoplankton and zooplankton were investigated at earthen ponds of white leg shrimp (Litopenaeus vannamei) in Delvar, Busher. During culture period, variation range of water temperature, salinity, dissolved oxygen and water transparency were 24-32ºC, 45-50 g/L, 3.5-5.5 mg/L and 60-140 cm, respectively. The dominant genera of phytoplankton communities were Navicula, Cosinodiscus, Nitzchia, Rhizosolenia and Pleurosigma from Bacillariophyceae, Peridinium and Ceratium from Dinoflagellates, Oscillatoria from Cyanobacteria, and Nannochloropsis from Chlorophyta. Investigation on zooplankton showed that their community mostly was copepod, rotifer, sergestid, polychaet, and crustacean larvae. The most abundant zooplankton assemblage was copepod which range of calanoid, cyclopoid and harpacticoid were 3-17 ind./L, 0.2-5 ind./L and 0-1 ind./L, respectively. The dominant genera of calanoid and cyclopoid were Acartia and Centropage, and Oithona, respectively, and harpacticoid had only one genus of Euterpina. Abundance of total zooplankton and total copepod had significant differences during culture of L. vannamei. Person’s correlations showed that there was significant correlation between abundance of calanoid and dissolved oxygen (r= -0.43) and salinity (r= -0.54) and also between abundance of cyclopoid and water temperature (r= 0.38) and pH (r= 0.32). In general, total zooplankton abundance had significant positive correlation with dissolved oxygen (r= 0.39) and pH (r= 0.37). Results of Principal Component Analyses (PCA) showed that rotifer abundance, pH and total zooplankton abundance as first factor and salinity and dissolved oxygen as second factor could be used to explain most of variation in zooplankton community in L. vannamei shrimp ponds.