食物种类和浓度对壶状臂尾轮虫实验种群动态的影响

使用浓度为0.3mg/mL的椭圆小球藻、尖细栅藻和两者以1:1(湿重比)组成的混合藻在26±1℃下对壶状臂尾轮虫进行单个体培养研究。结果表明,虽然三类食物对轮虫的胚胎发育时间和平均寿命无显著影响,但投喂小球藻时轮虫的生殖前期明显比投喂栅藻或混合藻时短,投喂小球藻时轮虫的生殖期明显比投喂栅藻时长；轮虫的生殖后期历时以栅藻组最长,混合藻组次之,小球藻组最短,三者间具显著差异。轮虫的繁殖率、产卵量和种群内禀增长率均以小球藻组最高,混合藻组次之,栅藻组最低。由此可见,小球藻是该种轮虫培养的最适饵料。以浓度为0.375、0.75、1.5、3.0和5.0×106cells/mL的椭圆小球藻为食物在23±1℃下对壶状臂尾轮虫进行单个体培养研究发现,0.75×106cells/mL是其生存和繁殖的最低浓度阈值;食物浓度对轮虫的胚胎发育时间和生殖后期历时无显著影响；食物浓度为1.5×106cells/mL和3.0×106cells/mL时,轮虫各主要发育阶段的历时和产卵量间也无显著差异；食物浓度高于3.0×106cells/mL或低于1.5×106cells/mL对轮虫的生殖前期无显著影响,但使轮虫的平均寿命和产卵量显著减小;食物浓度高于3.0×106cells/mL时,轮虫的生殖期显著缩短。轮虫种群的繁殖率、净生殖率和内禀增长率皆以3.0×106cells／mL组最高,1.5×106cells／mL组次之,0.75×106 cells／mL和5.0×106cells／mL组较低。因此,轮虫种群增长的适宜食物浓度范围为1.5-3.0×106cells／mL,最适食物浓度是3.0×106cells／mL。  

EFFECT OF FOOD SUPPLY IN BOTH FOOD QUALITY ANDQUANTITY ON THE POPULATION DYNAMICS OFBRACHIONUS URCEOLARIS

The effect of food quality on the population dynamics of B. urceolaris was studied at temperature of 26±1℃ and food concentration of 0.3mg/ml. Rotifers were cultured individually and fed on Chlorella ellipsoidea, Scenedesmus acuminatus or a 1:1 mixture (wet weighty) of these two algae. There were no significant differences in embryonic developmental times and mean lifespans with the type of diet.Rotifers fed on C. ellipsoidea had the shortest pre-reproductive and postreproductive periods, the longest reproductive periods, the highest reproductive rate, and the increasing number of eggs and intrinsic rate of population. Among the three types of diet,C.ellipsoidea was the best for the growth of B. urceolaris population.The effect of food quantity on the population dynamics of B. urceolaris was also studied in replicated individual cultures at temperature of 23 ±1℃ and at five concentrations (0.375, 0.75, 1.5, 3.0 and 5.0 ×106 cells/mL) of C. ellipsoidea. The lowest food concentration at which the rotifer survived and reproduced was 0.75×106cells/mL. There were no significant differences in embryonic developmental times and post-reproductive periods at different food concentrations, nor were the duration of principal developmental stages and the number of eggs at the food concentrations of 1.5 ×106 cells/mL and 3.0 ×106 cells/mL. The rotifers had shorter mean lifespans and produced fewer eggs when fed with the algae concentration of above 3.0 ×106 cells/mL or below 1.5 ×106 cells /mL; At the food concentration of above 3.0×106 cells/mL,the rotifers had shorter reproductive periods. The rotifers fed on the algae at the concentration of 3.0 ×106 cells/mL had the highest reproductive rate. Net reproductive rate and intrinsic rate of population increased among all the food concentration. The population growth of the rotifer was better at the food concentration from 1.5×106cells/mL to 3.0×106 cells/mL, and 3.0 ×106cells/mL was the best food concentration.