温度和盐度对鞍带石斑鱼受精卵发育及仔鱼成活率的影响

研究了在8个盐度梯度(18.3‰、19.7‰、21.2‰、23.5‰、25.6‰、27.1‰、29.5‰和31.7‰)下鞍带石斑鱼Epinephelus lanceol受精卵和仔鱼在水中的分布状态、出膜率和仔鱼存活率;在9个温度梯度(18℃、20℃、22℃、24℃、26℃、28℃、30℃、33℃和35℃)下,其受精卵孵化率、畸形率和仔鱼成活率。结果表明:(1)在水温为25~26℃,当盐度≤25.6‰时,受精卵表现为沉性;当盐度≥27.1‰时,受精卵表现为浮性。仔鱼的分布与受精卵有相似的特点,当盐度≤21.2‰时仔鱼分布在底层水体;当盐度≥27.1‰时,仔鱼集中分布在上层水体。(2)以孵化率和成活率为指标,鞍带石斑鱼孵化的适宜盐度范围为21.2‰~31.7‰,最适盐度范围为25.6‰~31.7‰。在盐度为31.7‰时仔鱼成活率最高达到75.9%。(3)鞍带石斑鱼胚胎发育的适温范围是26~30℃。28℃时受精卵孵化率、仔鱼成活率均最高,畸形率最低。

Effects of temperature and salinity on hatching rates and larval survival of Epinephelus lanceol

The effect of salinity and temperature on embryo and early larvae development of Epinephelus lanceol was discussed.The sinking and floatation of fertilized eggs and larvae under different salinities(18.3,19.7,21.2,23.5,25.6,27.1,29.5 and 31.7)were observed and compared,at the same time,we also observed hatching rates and survival rates.Besides,we set a serial of temperature,there were 9 levels(18,20,22,24,26,28,30,33 and 35 ℃) in our experiment.Under these conditions we determined the hatching rates of fertilized eggs,abnormal rates and the survival rates of larvae.The results showed :(1) when the temperature was 25～26 ℃,if the salinity was under 25.6,fertilized eggs were sinking.when above 27.1,eggs were floatation.The distribution of larvae under these salinity was similar to fertilized eggs.When the salinity was under 21.2 they were at the bottom of the water,when above 27.1 they swam in the surface layer.(2)The suitable salinity for hatching was from 21.2 to 31.7.The optimum was from 25.6 to 31.7.When the salinity was31.7,the survival rates reached the highest level of 75.9%.(3)The suitable temperature for hatching was from 26 ℃ to 30 ℃.When the temperature was 28 ℃,the hatching rates and survival rates reached the highest level,the abnormal rates were the lowest.