Abstract:Chlorella vulgaris was cultivated in nutrient media that contained different concentrations of nitrogen and phosphorus in order to investigate the influence of concentrations of nitrogen and phosphorus or their ratio on algal growth. Meanwhile, grazing experiments of Daphnia hyalina were conducted at different temperatures (11, 17, 23 ℃), using the cultivated C. vulgaris as food to study the impact of temperature and food quality on the growth and reproduction of D. hyalina. Experimental results indicated that of the three N∶ P atomic ratios (normal BG11 medium, N∶ P=76.77∶1; 1/5fold and 5fold N∶ P ratios in normal medium), 1/5fold N∶ P normal ratio offered the best conditions for C. vulgaris growth with the lowest N∶ P ratio in C. vulgaris cells than other conditions.C. vulgaris cultivated under 5fold N∶ P normal ratio has a little higher N∶P ratio of the algal body and gave C. vulgaris a lower growth rate than the normal medium group. We further fed D. hyalina with the different quality of C. vulgaris. Results revealed that, regardless of the temperature, the net reproductive rate (Ro)and generation time(T)of D. hyalina showed the highest values in low N∶P group (36.14-120.83, 24.61-35.56 d), followed by the middle N∶P group (16.29-59.39, 20.52-33.59 d), and the high N∶P group (13.02-38.99, 18.99-33.51 d). The intrinsic rate of increase(rm) of D. hyalina showed the highest values in high N and high N∶P group (0.115-0.179), followed by the low N∶ P group (0.105-0.152), and the low P and high N∶P group (0.081-0.128). Besides, water temperature was one of the factors affecting the growth and reproduction of D. hyalina. 17 ℃ was the optimum temperature for the growth and reproduction of D. hyalina.