Survey of diversity and density of planktons from Chahnimeh Reservoirs in Sistan

This study was carried out to identify، evaluate of the diversity and density of phytoplankton and zooplankton during the different seasons in 2009 and 2010 from Chahnimeh water reservoirs of Sistan in Zahak province. In survey of plankton community in the Chahnimeh reservoirs، 10 phylum and 34 geniuses of phytoplankton were obtained. In the seasonal comparison، most of phytoplankton geniuses were determined in spring with 18 geniuses and the least diversity obtained in winter with 7 geniuses. In spring، summer and autumn seasons، most of the geniuses to the phylum of Chlorophyta with 43472، 4085 and 68933 numbers in litter were determined respectively. In winter highest density of the phytoplankton obtained for phylum of Myzozoa with the 11293 number per litter and then the most of the density was counted for Chlorophyta with the 9517 number per litter. In the survey of zooplankton community of these reservoirs، 7 phylum and 22 geniuses were identified. The greatest diversity of zooplankton was determined with 22 geniuses in summer and the lowest were obtained in autumn with 3 geniuses. In spring the highest density of zooplanktons were counted to the phylum of Rotifera with the 1273 number per litter. In summer، autumn and winter seasons، the highest density of zooplanktons was to the Arthropoda with the 1056، 190 and 1064 number per litter respectively. In according to the results، the seasonal variations can be effect on variations of planktonic density and diversity in Sistan Chahnimeh Reservoir’s. Population growth and increase of diversity of phytoplankton and then zooplanktons community in spring season may be is due to the improve of environmental factors and source of production for phytoplankton.