The effect of salinity on embryo and early larva development of Dentex tumiforns was discussed. Floating forms of egg in different salinities, optimal salinity for embryonic development and early larva growth was studied. The results showed: 1. In immobile condition, all eggs sank at salinity of 32.0, most of eggs suspended in the middle of water at 34.0, and all eggs floated on the surface when salinity above 36.0. 2. Eggs did not hatch out at salinity of below 10.0 or above 60.0 and the death time of egg gradually moved up with increase or decline of salinity. Eggs hatched out at salinity range of 15.0 and 50.0,including abnormal larva. There was indistinct difference in speed of embryonic development (about 36-40h) within the salinity of 15.0 and 50.0. However the salinity had a great effect on larval survival after hatching and abnormal rate. The relation between hatching rate and salinity variation showed parabola but abnormal rate showed inverted parabola. The hatching rate was 81%-86% and abnormal rate of yolk sac larva was 27%-30% in suitable salinities of 27.0-(39.0). The hatching rate was 89%-91% and abnormal rate was 13%-16% in optimal salinities of 33.0-36.0. The oil ball of abnormal larva was located in the central or front position. With increased extent of salinity, spondyle of larva bended and number of larva with arrhythmia increased.3. The optimal salinities were 30.0-35.0 based on SAI. The test with SAI showed that SAI of early larvae was 41.25-47.53 at salinities of 30.0-35.0, the yolk and oil ball of 7-8 days larva was completely absorbed with a survival rate of 88%.
研究了温度和盐度对六斑刺鲀受精卵孵化的影响,实验选用了质量在600 g以上,体长20 cm以上的六斑刺鲀,将温度(A)设置为21℃,24℃,27℃,30℃,33℃五个水平;盐度(B)设置成18,22,26,30,34五个梯度,每组设三重复。每个平行100粒受精卵。结果表明:孵化时间随着温度的升高呈现逐渐降低的趋势;当温度在24℃~33℃时,孵化时间随着盐度的升高逐渐降低,且在盐度为18时孵化时间显著高于其他实验组。当盐度在26~34时,孵化率随着温度的升高呈现逐渐降低的趋势,且温度为24℃时的孵化率显著高于其他实验组(P P P <0.01)。综上所述,六斑刺鲀受精卵孵化最适温度在27℃左右,适宜孵化盐度在26~30。
