饥饿和光照对鳙仔鱼耳石沉积和日轮形成的影响

Effects of starvation and photoperiod on the otolith deposition and increment formation in the larval big head \%Aristichthys nobilis\%

用同１ 尾雌鱼催产孵出的鳙鱼仔鱼进行了饥饿、光照对耳石沉积和日轮形成影响的实验研究。结果表明， 仔鱼全长生长饥饿组慢于对照组， 差异极显著（ Ｐ ＜ ０ ．０１） ， Ｄ Ｄ （ 黑暗， 下同） 组、 Ｌ Ｌ （ 光照， 下同） 组与对照组接近， 无显著差异 （ Ｐ ＞ ０ ．０５） 。耳石直径各实验组与对照组无显著差异 （ Ｐ ＞ ０ ．０５） 。饥饿组仔鱼在体长生长停止的情况下耳石仍能继续沉积。仔鱼孵出后第２ ｄ 形成第１ 轮， 之后每天１ 轮， 对照组１６ 日龄仔鱼耳石上有１５ 个日轮。饥饿组约９０ ％ 的个体日轮数比对照组少２０ ％ ， 约１０ ％ 的个体耳石日轮不明显。 Ｄ Ｄ 组、 Ｌ Ｌ 组耳石日轮数通常比对照组多１ ～２ 个。实验结果说明饥饿一定时间后， 耳石日轮形成受阻。耳石日轮形成受内在的日周期性内分泌调控， 光周期只是日轮形成的伴随因子。

Effects of starvation and photoperiod on the otolith deposition and increments formation were observed in the larval big head incubated from fertilized eggs of same a femal fish. The total length of larva from starvation group grow significantly slow than control groups do (\%P<0.01\%), but the constant light (LL) and darkness (DD) groups approached to control groups significanty (\%P>0.05\%). The otoligh diameter of various test group was close with control groups. The otolith diameter of larva starvation group that could also be continual deposition under stagnated of body length. The initial daily growth increment in otolith was formed on the second day after hatched and continued on a daily schedule. There are 15 daily rings in otolith of larvae on 16 daily age of control group. The number of daily rings in otolith which about 90% individuals of starvation group was less 20% than control, however, daily rings in otolith 10% individuala was no obvious. The number of daily rings in otolith of DD and LL groups 1～2 more than contrast, respectively. The result in this study indicats that larva starved over 8 days disrupted increment formation. It seems, the increment was regulated by endocrinium of an endogenous circadian rhythm, while the photoperiod is only an accompanied factor for increment formation.