饥饿对圆口铜鱼Coreius guichenoti仔鱼早期发育的影响

Effects of Starvation on Feeding, Growth and Development of Coreius guichenoti Larvae

在水温(22.0±1.0)℃条件下,研究饥饿状态下圆口铜鱼Coreius guichenoti仔鱼生长、初次摄食率、不可逆点(PNR)以及摄食节律。结果表明:圆口铜鱼初孵仔鱼全长(7.50±0.01)mm,卵黄囊体积(3.36±0.11)mm^3,摄食组仔鱼全长生长呈线性增加,饥饿组仔鱼生长呈先增长后下降趋势。早期仔鱼(5日龄)和晚期仔鱼(15日龄)的摄食节律相似,高峰在凌晨6:00和黄昏18:00,属于典型的晨昏摄食类型。1~3日龄仔鱼为内源性营养期;4日龄仔鱼开口摄食,进入混合营养期,初次摄食率约为25.1%;5日龄卵黄囊耗尽,进入外源营养期;7日龄仔鱼摄食率达到最高水平为100%,最高摄食率维持6d,PNR期为13~14日龄。在本实验水温下,圆口铜鱼仔鱼最佳投喂时间为4~6日龄。

The effects of starvation on point of no return （PNR）, growth, initial feeding rate and feeding rhythm were studied in Cor- eius guichenoti larvae at water temperature of （22.0 ± 1.0） ℃. The results showed that newly-hatched larvae had total length of （7.50± 0.01 ） mm, with yolk sac of （3.36± 0.11 ） mm^3 in volume. The larvae in control group showed continuous increase in total length, while the starving larvae had first increase and then decrease in total length. A comparable trend of feeding rhythm was observed in early and late stage larvae, with feeding peaks at 6：00 and 18：00, indicating that Coreius guichenoti is typical morning-dusk feeder. The 1 - 3 day-old larvae showed endogenous nutrition, and the 4 day-old larvae had initial feeding, showing mixed nutrition, with initial feeding rate of 25.1%. The yolk sac was completely exhausted and the exogenous nutrients were found in 5 day old larvae. The maxi- mum initial feeding rate （ 100% ） appeared at the age of 7 days, and lasted for 6 days, and the PNR was observed in 13 - 14 day-old larvae. The optimal initial feeding time is suggested to be carried out from 4 d to 6 d after hatching.