| The life history characteristics of three Brachionus calyciflorus strains collected respectively from Guangzhou, Wuhu and Qingdao cities of China were comparatively studied. The main contents and results were presented as the following: 1. The reproduction-related characteristics of the three B. calyciflorus strains were studied by means of individual culture at 25±1℃with 2.0,5.0,8.0 and 11.0×106cell ·ml-1 of algae Scenedesmus obliquus as the rotifers'food. The results showed that the effect of food concentration on the duration of reproductive period and the percentage of mictic females in all the offspring were significant, but there was no significant effect on the number of total offspring. And three stated-above facts were all effected significant by strain. Among the three strains, Guangzhou strain had the longest reproductive period (4.53 ±0.19days), produced the largest number of offspring (18.75±0.26 individuals) in her lifetime, and had the lowest percentage of mictic females (4.32±0.51%) in all the offspring. Qingdao strain had the highest percentage of mictic female (49.90±2.15%) in all the offspring, but its duration of reproductive period and number of offspring produced in her lifetime were both similar to those of Wuhu strain. The interaction between food concentration and strain influenced markedly only on the percentage of mictic females in all the offspring. Among the three strains, the duration of reproductive period, the number of total offspring and the percentage of mictic females in all the offspring were significantly influenced by food concentration only for Wuhu strain. The effect of the age of rotifer mother on the percentage of mictic females in the offspring produced daily by her differed with both rotifer strain and food concentration. 2. The age of the rotifer of Wuhu strain at starvation had significant effects on lifespan, duration of the reproduction period and number of eggs produced in her life, but not on percentages of mictic females in the offspring produced during her life and starvation. The rotifer of Wuhu strain starved at the age of 1 day lengthened her lifespan and tolerance time to starvation by means of lowering her number of eggs produced in her lifetime. 3. The studies on the quality (egg and juvenile volume, tolerance time to starvation and duration of early developmental stage) of offspring produced by the three B. calyciflorus strains at 2.0,5.0,8.0 and 11.0×106cell ·ml-1 of algae Scenedesmus obliquus revealed that food concentration affected significantly on the egg volume and the juvenile volume of the rotifer. The biggest egg was produced by the rotifer at the food concentration of 2.0×106cell ·ml-1, but other eggs produced at the other three food concentrations were similar in volume. The largest juvenile was hatched from the egg produced at the food concentration of 8.0×106cell ·ml-1, but the smallest at 5.0×106cell ·ml-1. Strain influenced markedly on the egg and juvenile volumes, the durations of early developmental stages and the tolerance time of offspring to starvation. Among the three strains, the egg and juvenile volumes of Guangzhou strain were the biggest, the embryonic developmental time and the duration of juvenile period were the longest, but the tolerance time of offspring to starvation was the shortest. There were significant effects of the interaction between food concentration and strain on all the egg and juvenile volumes, the duration of juvenile period and the tolerance time of offspring to starvation. The mother's age affected significantly only on the egg volume of Wuhu strain, with the egg produced by her mother at the age of 1 day being markedly larger than that at the age of 4 days. 4. The feeding intensity of the Guangzhou and Wuhu strains of Brachionus calyciflorus in relation to food concentration, food type and cultural time was compared, and the result showed that the three stated-above factors all had significant effects on filtration and ingestion rates of the rotifer. The filtration an...
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