星斑裸颊鲷胚胎及卵黄囊期仔鱼发育研究

Embryonic development of yolk saclarvae of Lethrinus nebulosus Forskl

对星斑裸颊鲷(Lethrinus nebulosus Forskal)的胚胎发育过程做了详细的观察和描述,并跟踪了孵化仔鱼的生长情况.结果表明,星斑裸颊鲷受精卵为浮性卵,卵径0.761 mm士0.019 mm,在水温27℃士1℃,盐度30～32的条件下,受精后约16.5 h孵化;在水温25℃±1℃,盐度30～32的条件下,受精后约17.83 h孵化.初孵仔鱼全长1.739～1.772 mm,仔鱼孵出2 d后开口,卵黄囊与油球已基本消耗完毕,大部分仔鱼开始摄食L-S型轮虫,开始由内源营养期向外源营养期过渡.同时发现在不同温度下,胚胎发育的时间、初孵仔鱼的大小、生长速度及卵黄囊的大小均不同.

The embryonic development of yolk sac larvae of Lethrinus nebulosus, an enviromental scavenger, was studied. Results show that the fertilized eggs of the Lethrinus nebulosus are transparent, spherical and sized between 0. 761 and 0. 771 mm. The eggs contain a single oil globule in the sizes from 0. 139 to 0. 151 mm. At water temperature of 26-28℃ and salinity of 30-32, the larvae were hatched out 16.5 h after fertili- zation, while at 24-26℃ and 30-32, the time was 17.83 h. The body length of newly hatched larvae ranged 1. 739-1. 772 mm, that of 1-day-old larvae ranged 2. 380-2. 391 mm and that of 2-day-old larvae ranged 2. 389~2. 478 mm. The yolk sac was absorbed greatly about 38-42 h, and the larvae started to feed 2 days after the hatch, then they could take rotifers. The yolk sac and oil globule disappeared 3 days after the hatch.