长江口纹缟虾虎鱼早期发育对生态因子的适应性

The adaptability of embryos and larvae of Tridentiger trigonocephalus at the Yangtze River estuary to ecological factors

纹缟虾虎鱼广泛分布于长江口水域,是许多水生动物的重要饵料,在长江口水生生态系统中具有重要地位。2007年在人工繁殖基础上系统研究了长江口纹缟虾虎鱼(Tridentiger trigonocephalus)胚胎与仔鱼的发育特征及其与温度、光照、pH等生态因子的关系。结果表明,温度上升时纹缟虾虎鱼胚胎发育速度加快,受精率与孵化率下降,17～21℃是纹缟虾虎鱼胚胎发育的适宜温度,胚胎发育有效积温模型为:N=3128.3/(T-4.36),温度系数Q10值为1.33～2.84;随着温度升高,仔鱼器官发育速度与卵黄囊被吸收速度加快,但存活率下降。不同光照周期中,长光照组胚胎比自然光照组与长黑暗组发育快,但孵化率低;仔鱼亦是长光照组比自然光照组与长黑暗组发育快。pH升高时纹缟虾虎鱼胚胎孵化率升高,发育速度加快;高pH组(pH 7.5～9.5)水体中仔鱼发育较快,活力较好,发育特征亦更加明显,畸形率较低。综合各项指标表明,长江口纹缟虾虎鱼早期发育的适宜生态条件为:温度17～21℃,每昼夜光照12h以上,pH 7.5～9.5。长江口生态环境变动可能会对纹缟虾虎鱼早期发育及其资源量产生一定影响。

Tridentiger trigonocephalus widely distributed at the Yangtze River estuary with abundant population.Young T.trigonocephalus is an important prey for many aquatic animal species at the Yangtze River estuary.However,studies of effects of ecological factors on the early life stages of T.trigonocephalus are scarce.Because of pollution and large scale constructions,the environmental conditions of the Yangtze River estuary have been changing recently.It is necessary to understand the effects of environmental changes on the early life stages of fishes in the estuarine area.In this study,the ecological adaptability of embryos and larvae of T.trigonocephalus were investigated.The experimental results showed that the fertility rate and hatching rate reduced with the increase of water temperature.Temperature ranging from 17℃ to 21℃ is an optimal water temperature for the development of the embryos.The model of effective accumulative temperature for the embryonic development is N = 3128.3 /（T-4.36）,and the range of temperature coefficient Q10 was from 1.33 to 2.84.The larva development speeded up,but the survival rate reduced with the increase of temperature.The embryonic development speeded up,but the hatching rate reduced when the photoperiod was increased.Moreover,the larval development also speeded up with the increase of photoperiod.The embryonic development speeded up and the hatching rate rose with the increase of pH value.The larva development also speeded up and the abnormality rate rose with the increase of pH value,e.g.,the activity ability of high pH value groups（pH 7.5,pH 8.5 and pH 9.5） was better than that of low pH value groups（pH 4.5,pH 5.5 and pH 6.5）.In conclusion,the optimal ecological factors for the early life development of T.trigonocephalus were 17℃ to 21℃ of water temperatures,over 12-hour of daily photoperiod,and 7.5 to 9.5 of pH values.It may be inferred that the early life development and the population dynamics of T.trigonocephalus may be influenced by the environmental alteration at the Yangtze River estuary.