长江口纹缟虾虎鱼胚胎发育及早期仔鱼生长与盐度的关系

EMBRYONIC AND PRE-LARVAL DEVELOPMENT OF TRIDENTIGER TRIGONOCEPHALUS AND ADAPTABILITY TO SALINITY

研究了长江口纹缟虾虎鱼(Tridentiger trigonocephalus)胚胎发育及早期仔鱼生长与盐度的相关性。纹缟虾虎鱼胚胎发育时,盐度4与6试验组效果较好,受精率分别达(76.28±2.73)%与(74.63±5.49)%,孵化率分别达(66.95±2.99)%与(62.15±2.18)%,出膜时间分别为(228.8±5.9)h与(221.5±5.2)h,器官发育特征较明显,畸形率较低。纹缟虾虎鱼仔鱼发育时,初孵仔鱼全长(2.534±0.078)mm,卵黄囊长径(0.421±0.047)mm,短径(0.369±0.038)mm,5日龄时卵黄囊基本消失,初步形成消化器官、循环器官和运动器官等。盐度8与10水体孵育的仔鱼畸形率达5%-20%,其他试验组略低。盐度4与6试验组仔鱼的器官发育速度快于其他3个试验组。盐度0-6试验组纹缟虾虎鱼仔鱼生存活力指数(SAI)为41.83-46.83,仔鱼活力较好,而盐度8-10试验组SAI值为23.43-29.13,活力较差。综合各项指标表明,在盐度0-10范围内,长江口纹缟虾虎鱼胚胎发育的适宜盐度为4-6,早期仔鱼生长的适宜盐度为2-4。

Tridentiger trigonocephalus widely exists in coast of the Pacific Ocean. There are very few reports about the character of their early life. Fish was sensitive to the change of environmental factors in the early life. So embryo and larva can indicate the environmental change. Salinity is one of the most important ecological factors in the embryonic and pre-larval development of T. trigonocephalus. The construction of the Three Gorges Project on the mainstream may act on the environment not only in the reservoir, the middle and low reaches of the river, but also in the estuary. It is necessary to study the relationship between salinity and fish early life. By observing the morphological character of embryonic and pre-larval development of T. trigonocephalus with Nikon microscope,the total development time of every development stage was noted and calculated. The characteristic images were taken by Nikon camera. The characters of early life stages and effects of salinity on the early development of T. trigonocephalus were studied. The experimentation groups included salinities of 0,2,4, 6,8 and 10 ,respectively. Every group was put into 100 oosperm or 10 prearva under the water of temperature （18.0± 0.5℃ ） ,deliquescent oxygen 6.6--8.2 mg/L, pH7. 2--7. 8. The results showed fecundation rate and hatching rate were the highest at salinities of 4 and 6. Fecundation rate was （ 76.28 ± 2.73 ） % and （74.63 ± 5.49 ） % , and hatching rate was （66.95 ±2.99）% and （62. 15 ±2. 18）% ,respectively. Hatching time was the shortest and embryonic development was the most quickly at salinities of 4 and 6. Hatching time was 228.8 ± 5.9h and 221.5 ± 5.2h, respectively. It spent longer time from heart beating stage to hatching stage ,56 percent of the total time. Meanwhile, pectoral fin, swim-bladder, kidney and bladder came into being before pre-stage of hatching stage. The deformity rates were from 5% to 20% at sallnities of 8 and 10 and the other salinities were lower. The larva was （2. 534 ± 0. 078 ）mm in body length. The long and short diameter of yolk sac were （0. 421 ± 0. 047 ）mm and （0. 369± 0. 038 ）mm, respectively. The yolk sac disappeared and organs begin to form after five days. The organ development of larval T. trigonocephalus was more quickly at salinities of 4 and 6 than the others. The range of survival activity index was from 41.83 to 46.83 and pre-larva vigor was high with water salinity from 0 to 6. The range of survival activity index was from 23.43 to 29.13 and pre-larva vigor was low at salinity of 8 and 10. At low salinity range, the suitable salinity for hatching was from salinity 4 to 6 and for pre-larvae survival and growth was from salinity of 2 to 4,respectively.