Effect of stocking density of Procambarus clarkii on plankton community in pond

This paper studied the variations of plankton community in ponds, in which Procambarus clarkii and Eriocheir sinensis were stocked in three densities. The results showed that because zooplankton fed on phytoplankton, their quantities were in negative correlation in the most ponds. With the increasing of density, the biomass of phytoplankton increased and the forms of Euglenophyta, Cyanophyta, Pyrrophyta instead of Bacillariophyta and Chlorophyta became dominant group in the high density groups, but zooplankton爷s biomass decreased, supported by Protozoa, Rotife and Nauplius. The biomass ratio of zooplankton/phytoplankton showed significant negative correlation with stocking density of shrimp and crab. The results of this study indicated that the medium stocking density was optimum so as to give consideration to the ecological benefit and economic benefit.