| Brachionus angularis is usual specie in fresh water, and is considered to have important status in material cycle and energy transportation in fresh water ecosystem, and applied value in aquaculture. The effects of temperature, food type, food concentration on body size strategy, reproduction strategy of three B. angularis strains (QD, WH, and GZ strain, collected respectively from Qingdao, Guangzhou and Wuhu city) were studied in this article. The main contents were presented as following:1. By means of population accumulative culture, the effects of temperature (20℃, 25℃, 30℃), food type (3.6×106 cells · ml -1 Scenedesmus obliquus, 9.0×106 cells · ml -1 Chlorella pyrenoidosa, and mixed algae of 1.8 ×106 cells · ml -1 S. obliquus and 4.5×106 cells · ml -1 C. pyrenoidosa), and food concentration (S. obliquus at five food levels, 0.4, 0.8, 1.6, 3.2 and 6.4×106cells · ml-1) on the population growth, body size, and egg size of the three strains of freshwater rotifer B. angularis were studied. Comparative studies of growth and the reproduction strategy of the three strains at different clutch size were also studied.Temperature affected the population growth rate, body size, and egg size significantly. The optimum temperature of population growth of QD strain was 30℃, and that of GZ strain was 25℃. But WH strain had 100% mortality at 30℃. The relationships between the temperature and the population growth rate of both QD and GZ strain were curvilinear, with the regression equation Y= 0.0009X2 - 0.0061X + 0.4090 and Y= - 0.0144X2 + 0.7412X - 8.3751, respectively. Both body size and egg size tended to decrease with the increasing temperature. In our experimental temperature range, the variation of body size was 42.90% in GZ strain, 14.43% in QD strain, and 6.23% in WH strain. Among the three strains, the body size of WH strain was the largest, and that of QD strain was the smallest. At 20℃ and 25℃, the body size of WH strain was 74.91% and 87.98% larger than QD strain. Strain had a more important effect on the rotifer body volume than temperature.Food type and strain affected the population growth rate, body volume, egg volume and relative egg size significantly. The rotifers fed C. pyrenoidosa had the smallest population growth rate and egg volume. The rotifers fed S. obliquus and mixed algae were larger than those fed C. pyrenoidosa. The amplitude of variance of body size affected by algal type was 28.92%, 37.13% and 9.57% in GZ, WH and QD strains, respectively. Fed each type of algal food, WH strain had the smallest population growth rate, the largest body volume and egg volume among all the three strains. The difference between the largest WH strain and the smallest QD strain was 47.89%, 81.37% and 70.47% when the food was C. pyrenoidosa, mixed algae, and S. obliquus, respectively. Strain had a more important effect on body volume of B. angularis than algal food type.The population growth rate, body and egg size, and neonate size were significantly affected by food concentration and strain. The relationships between the food concentration and the population growth rate of GZ, WH, and QD strain were all curvilinear, with the following regression equations, Y= - 0.0268X2 + 0.1718X + 0.6242, Y= - 0.0238X2 + 0.2489X + 0.1997 and Y= - 0.0506X2 + 0.4571X + 0.0737, respectively. Among the three strains, the food concentration at which GZ strain needed to get its largest population growth rate (0.8995d-1 ) were 3.2052×106cells · ml-1, and QD strain got its largest r value (1.1060d-1) when the food concentration was 4.5168×106cells · ml-1. At 5.2290×106cells · ml-1, r of WH strain got its maximum, 0.8504d-1. Body size, egg size, and neonate size at higher food concentration were all larger than those at lower food level. Among the three strains, WH Strain had the largest body size, egg size, and neonate size. But the relative egg size of WH strain was the smallest, and that of QD strain was the largest. Strain had a more important effect on the rotifer body size than food concentrat...
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