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

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.