Study on the interactions among Chlorella vulgaris, Daphnia magna and Ceratophyllum demersum in simulated natural water
模拟自然水体中藻-溞-草间的相互作用研究

In order to determine the influences of nitrogen and phosphorus concentrations in the biomanipulation and restoration of aquatic vegetation, Chlorella vulgaris, Daphnia magna and Ceratophyllum demersum, the representative of phytoplankton, zooplankton and submerged macrophyte, were used to study the effects of nitrogen and phosphorus concentration on their growths and interactions in the natural water. The results showed that C. demersum had no obvious growth or negative growth when C. demersum and C. vulgaris were cultured together, and nitrogen and phosphorus concentration ranges were 2.92~12.60 mg·L-1, 0.06~0.85 mg·L-1, with C. vulgaris growing better than C. demersum. When D. magna and C. vulgaris were cultured together at nitrogen and phosphorus concentrations of 1.26~10.53 mg·L-1 and 0.04~1.16 mg·L-1, respectively. D. magna inhibited the growth of C. vulgaris. The removal rates of nitrogen and phosphorus were greater than those of co-culture of C. demersum and C. vulgaris, and the removal rate of phosphorus was higher than that of nitrogen. When the three organisms were cultured together at nitrogen and phosphorus concentrations of 3.15~23.92 mg·L-1 and 0.07~0.64 mg·L-1, respectively, D. magna and C. demersum showed a higher growth rate, while C. vulgaris had a lower growth rate, and the water quality became better. However, when nitrogen and phosphorus concentrations were 25.95 mg·L-1 and 1.18 mg·L-1, respectively, their growth rates became lower and the water quality became worse. The combined inhibition of D. magna and C. demersum on C. vulgaris was more effective than the independent inhibition. The effect of algae control was obviously influenced by the concentration of nitrogen and phosphorus in water.