双棘刺尻鱼的胚胎发育和仔鱼早期发育研究

Embryonic and early larval development of marine angelfish Centropyge bispinosa

本研究报道了一种分布广泛的小型珊瑚礁鱼——双棘刺尻鱼(Centropyge bispinosa)的胚胎发育和仔鱼早期发育过程。结果表明,双棘刺尻鱼在关灯(日落)后10~20 min产出配子,其受精卵呈透明圆球状,卵直径为638.5±5.7μm,卵内存在单一油滴,直径为179.9±10.3μm,油滴内部占据空间最多的是卵黄。在24.5℃的水温下受精后16 h 30 min孵化。初孵仔鱼体长为1161.3±55.2μm,大量器官尚未发育完全,无口和消化道,眼睛无色素沉淀,不具备主动游泳的能力。孵化后第1天其体长快速发育至2241.7±54.2μm,卵黄大部分被吸收,躯干上出现较大的色素细胞。孵化后第2天仔鱼体长发育速度减缓,增长至2476.4±12.7μm,但是同时重要器官如消化道、肛门发育完成,卵黄几乎全部被吸收。孵化后第3天,体长几乎没有增长,但是眼睛完成色素沉淀开始发挥功能,口部也发育完成,开始进入外源性营养阶段,有能力对猎物和捕食者做出反应。本研究为国内首次报道双棘刺尻鱼胚胎和幼体发育过程,为未来进一步开展该鱼的人工繁育工作奠定了基础。

Our study described the embryonic and early larval development of Centropyge bispinosa,a representative marine ornamental pygmy angelfish which widely distributed in Indo-Pacific coral reefs.Results show that broodstock of C.bispinosa releases gametes in 10-20 minutes after the lights off(sunset).The fertilized eggs are spherical in shape and 638.5±5.7μm in diameter,with an oil droplet inside(179.9±10.3μm)and the yolk occupying the most inner space of egg.At 24.5℃,the hatching occurred after fertilization in about 16.5 hours.The average body length(BL)of the newly hatched larvae is 1161.3±55.2μm.The newly hatched larva lacks mouth and digestive tract,incapable of active swimming due to the lack of pigmented eyes and other essential organs.In 1 day post hatch(dph),the average BL of larvae grew up to 2241.7±54.2μm,their yolks were partly absorbed,and large pigment cells began to appear on the body.In 2 dph,the larvae grew up to 2476.4±12.7μm,which indicates a decreased growth rate of BL and suggests that energy budget for growth may compensate for the development of important organs such as the digestive tract and anus.In 3 dph,the average BL of the larvae changed insignificantly,while the eyes were fully pigmented,the mouth was developed and began to enter the exogenous nutrition stage,which makes the larvae responsible to prey and predators.For the first time,this study reported the embryonic and larval development of pygmy angelfish C.bispinosa in China.It provides a guide for the breedings of pygmy angelfish in captive in future.