设计4种点光源(100 lx、320 lx、960 lx、1920 lx)光照模式，以黑暗和面光源(68 lx)模式为对照，以30 min为实验周期，对中华鲟(Acipenser sinensis)子二代仔、幼鱼(5~29日龄)的趋光行为进行观察和统计分析。结果表明，仔鱼处于平游期(5~8日龄)时，点光源光照条件下活动鱼苗的趋光率显著高于对照组(黑暗环境和面光源)(P<0.05)，而且点光源光照条件下活动鱼苗的趋光率随着光照强度的增强而增加，并在1920 lx与100 lx和320 lx间存在显著性差异(P<0.05)。平游期仔鱼的趋光性最为明显，在设定的4种点光源光照强度中，在100 lx的低强度光照下趋光性最强，在960 lx光照强度下趋光性最弱，且二者存在显著性差异(P<0.05)；中华鲟子二代进入沉底期以后，光照的影响作用明显减弱，仔鱼基本失去趋光性。研究表明，中华鲟子二代仔鱼具有平游期趋光性最强、趋弱光和沉底之后基本失去趋光性等行为特点，这种趋光行为与野生中华鲟仔鱼基本一致。研究结果可为阐明中华鲟全人工繁殖后代生态适应性提供参考。%Chinese sturgeon (Acipenser sinensis) is a species of anadromous migratory large fish living for decades, and is a special rare fish in China. In 2009, we got the second filial generation (F2) from the F1 of this species by complete artificial propagation under fresh water, which meant China got successful progress in conservation of A. sinensis. But the question is if there exists difference in biologic characteristics between the wild species and arti-ficial F2. In this study, we tested the response of larval A.sinensis F2 to four light intensities (100, 320, 960, and 1 920 lx), and two modes of illumination (dark and surface light source). The phototactic behavior of each indi-vidual was observed for 30 min/d for 24 consecutive days. Between 0-8 d after hatch (dah), the individual ratio of phototaxis movement in the groups under the dark treatment and surface light source illumination was signifi-cantly lower (P<0.05) than for those exposed to the point light source. Furthermore, the individual ratio under the point light treatment increased with increasing light intensity, and there was a significant difference in the ratio at 320 lx and 1 920 lx or 100 lx (P<0.05). At 8 dah, there was evidence of larval phototaxis at all four point light source intensities, though phototaxis was significantly higher at 100 lx than at 960 lx (P<0.05). The larvae were positioned on the bottom of the plastic jar and did not exhibit any significant phototaxis. Our results suggest that the second filial generation of Chinese sturgeon larvae are very sensitive to weak light between 0-8 dah, and gradually lose phototaxis after that time. This is consistent with observations of phototactic behavior in wild Chinese sturgeon larvae.
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