Study on the biological function of tropical minute rotifers and its application for mass preservation of live food.

1.以印度尼西亚、泰国和西班牙3个轮虫品系为材料，进行了SS型轮虫遗传特性的杂交试验。轮虫的交配行为包括雄虫在雌虫冠上接触，雄虫在雌虫冠上盘旋，交配，然后受精。通过在5 ml培养皿中共培养100只雌性和50只雄性，监测交配频率并获得受精率。在SS株系杂交中，交尾率为5.0 ~ 16.6%，受精率为7.7 ~ 34.7%。本试验未观察到S和SS之间的交配和受精现象，而其他S和SS菌株均有交配和受精现象的报道。在S和SS菌株群中可能都存在较大的遗传变异。在10℃和12℃条件下，ss轮虫可保存14天。在25℃条件下，γ -氨基丁酸的添加量为50 ug/mL，可促进种群生长。当培养温度从30℃变化到25℃时，静息产蛋量显著高于保持30℃时。在使用500L水箱的大规模试验中，轮虫在9天的实验中产生了2.6 × 10^6个休眠卵，是没有温度变化的轮虫数量的1.6倍。维持SS型轮虫密度分别为3、10和30只/ml时，第6、7天石斑鱼幼虫摄食率降低，第7天幼虫总长度最小。第8天之后，各处理间无差异。供体轮虫的罗瑞卡长度为80 ~ 156um（平均罗瑞卡长度为114um），而幼虫摄食的罗瑞卡长度为75 ~ 138 um（平均104 um）。因此，这一阶段的石斑鱼幼虫只能摄食较小的SS轮虫类。

1.Genetic characteristics of SS type rotifersCrossbreeding experiments were conducted using three rotifer strains from Indonesia, Thai and Spain strains. Rotifer mating behavior involves male contact on female corona, male circling around female lorica and copulation, followed by fertilization. The frequency of mating was monitored and percent fertilization was obtained, by co-culturing 100 females and 50 males in a 5 ml petri dish. In the crossing between SS strains, percent copulation and fertilization were 5.0-16.6% and 7.7-34.7%, respectively. No copulation and fertilization was observed between S and SS strains in this experiment, whereas such cases were reported with other S and SS strains. A large genetic variation probably exists both in S and SS strain groups.2.Reproduction and mass preservationSS rotifers could be preserved for 14 days at 10 and 12℃. The addition of gamma-aminobutyric acid at 50 ug/mL increased population growth at 25℃. Significantly higher resting egg production was observed when the culture temperature was changed from 30 to 25℃, than when temperature was kept at 30℃. In the large-scale trial using 500L tanks, rotifers produced 2.6x10^6 resting eggs during a 9-day experiment, which was 1.6 times more than the number of rotifers without temperature change.3.Larval rearing of grouper using SS rotifersBy maintaining the SS type rotifer density at 3, 10 and 30 ind./ml, ingestion rate of grouper larvae was reduced on day 6 and 7, and total length of larvae on day 7 was also the smallest. After day 8 however, no difference was found among treatments. The lorica size of supplied SS rotifers ranged from 80-156um (average lorica length=114um), while larvae ingested rotifers whose lorica length was from 75 to 138 um (104 um in average). Thus, grouper larvae at this stage could ingest only smaller size class of SS rotifers.