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

1. SS型轮虫的遗传特性用印度尼西亚、泰国和西班牙的3个品系进行了杂交育种试验。轮虫的交配行为包括雄虫在雌虫冠上接触，雄虫环绕雌虫洛里卡交配，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百分比。SS品系间杂交的交配率和受精率分别为5.0-16.6%和7.7- 34.7%。在本实验中，S和SS菌株之间没有观察到交配和受精，而其他S和SS菌株则报告了此类情况。SS品系和S品系之间可能存在较大的遗传变异。2.繁殖和大量繁殖SS轮虫在10 ℃和12℃下可保存14 d。在25℃下，添加50 μ g/mL的γ-氨基丁酸可增加种群生长。培养温度在30 ~ 25℃范围内变化时，休眠卵产量显著高于30℃。在500 L罐的大规模试验中，在9天的实验中，轮虫产生了2.6x10^6个休眠卵，是没有温度变化时轮虫数量的1.6倍。3.利用SS型轮虫饲养石斑鱼幼虫通过维持SS型轮虫密度为3、10和30 ind./ ml时，石斑鱼仔鱼的摄食率在第6、7天降低，第7天仔鱼的全长也最小。然而，在第8天之后，没有发现处理之间的差异。投喂的SS轮虫的洛里卡大小为80- 156 μ m（平均洛里卡长度为114 μ m），仔鱼摄食的轮虫的洛里卡长度为75 ~ 138 μ m（平均104 μ m）。因此，石斑鱼幼虫在这个阶段只能摄取较小尺寸的SS轮虫。

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.