温度对云纹石斑鱼(Epinephelus moara)胚胎发育和仔鱼活力的影响

Effects of Temperature on the Embryonic Development and Larval Activity of Epinephelus moara

关键词:  云纹石斑鱼  温度  胚胎发育  仔鱼活力

Key words:  Epinephelus moara  Temperature  Embryonic development  Larval activity

摘要:

研究了不同孵化温度(16℃、18℃、20℃、22℃、24℃、26℃、28℃和30℃)对云纹石斑鱼(Epinephelus moara)胚胎发育的影响，记录并分析不同温度处理组受精12 h后的胚胎发育时期、受精卵的孵化周期、孵化率和初孵仔鱼的畸形率，并对初孵仔鱼进行不同温度下的饥饿耐受性实验，测定其每天的存活率和生存活力指数(Survival activity index，SAI)。结果显示，当温度在18–28℃范围内时，胚胎均可孵化出仔鱼，且孵化时间随温度的升高而缩短，孵化时间y与温度x呈极显著的负相关关系，y=12139x−1.869，R2=0.993(P<0.01)。22℃时受精卵孵化率最高，为71.01%，该温度下对应最低畸形率(9.70%)，其次为24℃时，受精卵孵化率为65.37%，畸形率为13.07%；温度低于22℃时，孵化率逐渐降低，18℃时的孵化率为24.39%；温度高于22℃时，孵化率亦明显降低，28℃孵化率最低，为16.11%，而畸形率的变化趋势与孵化率相反。温度为16℃时，受精卵发育至高囊胚期后不再继续发育；温度为30℃时，胚胎停止于胚体形成期。仔鱼的SAI值随着温度的升高先升高后降低，在20℃时，SAI值最高(25.97)，仔鱼的半数死亡时间最长为7 d；22℃时，SAI值有所降低(22.38)，仔鱼在该温度下半数死亡时间为6 d。分析结果可知，云纹石斑鱼受精卵培育的最适温度为22–24℃，仔鱼孵化的最适温度为20–22℃。

Abstract:

In this study we investigated the effect of incubation temperatures (16℃, 18℃, 20℃, 22℃, 24℃, 28℃, and 30℃) on the embryonic development and larval activity of the Epinephelus moara. The stage of embryonic development after 12 hours of hatching, the hatching rate and the deformity rate of newly-hatched larvae were also measured and analyzed. We performed the starvation test on the newly-hatched larvae and evaluated their daily survival rate and the survival activity index (SAI) at different temperatures. It showed that the embryos could be hatched at 18−28℃. The hatching time was negatively correlated to the temperature as shown in the equation y=12139x−1.869 (R2=0.993, P<0.01), in which y was the hatching time and x was the temperature. The highest hatching rate (71.01%) and the lowest deformity rate (9.7%) were observed at 22℃. A lower hatching rate (65.37%) and higher deformity rate (13.07%) appeared at 20℃. The hatching rate decreased gradually when the temperature was below 22℃, and reached 24.39% at 18℃. The hatching rate also decreased significantly when the temperature was above 22℃, and the lowest hatching rate (16.11%) appeared at 28℃. The effect of temperature on the deformity rate of newly-hatched larvae showed an opposite pattern. The embryonic development stopped at the stage of blastula at 16℃. At 30℃, the cell dividing ceased at the embryo body stage. The SAI first increased and then decreased along with the rise in the temperature. At 20℃, SAI of the larva was the highest (25.97) with the longest half-death time of 7 d. Therefore, the optimal hatching temperature for the fertilized eggs of E. moara could be 22–24℃, and the most suitable temperature for the survival of newly-hatched larvae could be 20–22℃.