豹纹鳃棘鲈仔鱼饥饿实验和不可逆点研究

Experimental starvation of Plectropomus leopardus larvae and study of point of no return

  • 摘要: 采用实验生态学方法研究了饥饿对豹纹鳃棘鲈(Plectropomus leopardus)仔鱼形态发育、生长和成活的影响,并测定了饥饿仔鱼的初次摄食率和不可逆点(PNR)。结果显示,水温23~24 ℃下豹纹鳃棘鲈仔鱼2.5 DPH(孵化后天数)开口摄食,3.0 DPH卵黄囊和油球消失,混合营养期仅0.5 d,容易遭受饥饿胁迫。饥饿仔鱼最高初次摄食率为65%,出现在3.5 DPH; PNR发生在4.5~5.0 DPH,仔鱼具有初次摄食能力的时间仅2.0~2.5 d。对照组和饥饿组仔鱼在3.5 DPH前全长无明显差异(P>0.05),之后饥饿组仔鱼出现生理性萎缩,全长开始与对照组差异显著(P < 0.05)。饥饿组仔鱼在内源性营养消耗完毕后出现了一系列因饥饿所导致的形态发育特征,并于6.5 DPH全部死亡,因此豹纹鳃棘鲈仔鱼最佳投喂时间为2.5~3.5 DPH。

     

    Abstract: In the present study, we investigated the effects of starvation on morphological development, growth and survival of Plectropomus leopardus larvae using experimental ecological method, and determined the initial feeding rate and point of no return (PNR) of the starved larvae. The results show that the larvae began to eat on 2.5 days post hatch (DPH) following by disappearance of yolk sac and oil globule on 3.0 DPH at water temperature of 23~24 ℃. Therefore, the larvae were vulnerable to starvation stress with only 0.5-day mixed vegetative period. The highest initial feeding rate was 65% on 3.5 DPH. The PNR was detected on 4.5~5.0 DPH, with only 2.0~2.5 d of initial feeding. The average total length in the starved group was not significantly different from that of control group before 3.5 DPH (P > 0.05), but after then it decreased significantly compared with the control group because of physiological atrophy (P  < 0.05). After endogenous nutrients being absorbed completely, a series of hunger-induced morphological characteristics appeared in starved group and all larvae died on 6.5 DPH. In conclusion, the optimum initial feeding time for P.leopardus is 2.5~3.5 DPH.

     

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