温度、盐度、pH和体质量对尼罗罗非鱼幼鱼窒息点的影响

利用实验生态学的方法研究不同温度(15、20、25、30和35℃)、盐度(0、5、10、15和20)、pH(5、6、7、8和9)和体质量(1.93±0.08、3.43±0.12、7.95±0.34、11.74±0.41和15.84±0.61 g)对尼罗罗非鱼幼鱼窒息点的影响,并建立温度、盐度、pH、体质量与罗非鱼窒息点间的回归方程。结果表明:温度t、盐度S、pH和体质量m对尼罗罗非鱼幼鱼窒息点有显著影响(P<0.05)。当温度、盐度、pH和体质量分别为25.28℃、3.6、8.06、6.3 g时,窒息点(DAP)最低,回归方程为DAP=0.000 9 t 2-0.045 5 t+0.726 6(R2=0.952 1),DAP=-0.000 1 S 3+0.004 2 S 2-0.023 9 S+0.111 9(R2=0.922 8),DAP=0.009 3 pH2-0.149 9 pH+0.7174(R2=0.976 8);DAP=-0.000 3 m3+0.011 1 m2-0.104 3 m+0.362 8(R2=0.948 4)。在溶氧不足情况下,温度25.28℃、盐度3.6、pH 8.06的环境条件有助于提高幼鱼耐低氧能力。

Effects of Temperature, Salinity, pH and Body Weight on Asphyxiation Point of Juvenile Nile Tilapia (Oreochromis niloticus )

The effects of temperature(15,20,25,30 and 35 ℃),salinity(0,5,10,15 and 20),pH(5,6,7,8 and 9) and body weight(1.93 ± 0.08,3.43 ± 0.12,7.95 ± 0.34,11.74 ± 0.41 and 15.84 ± 0.61 g) on Nile tilapia juvenile exposed to hypoxic stress were studied by means of the experimental ecology method in laboratory.Regression models for the effects of temperature,salinity,pH and body weight on asphyxiation point(DAP) were derived from the data.The results showed that these factors had significant effects on asphyxiation point(P < 0.05).The asphyxiation point arrived at the minimum when temperature(t),salinity(S),pH and body weight(m) were respectively 25.28 ℃,3.6,8.06 and 6.3 g.The regression equation between asphyxiation point and the factors above mentioned was as follows: DAP = 0.000 9 t 2-0.045 5 t + 0.726 6,R2 = 0.952 1;DAP =-0.000 1 S 3 + 0.004 2 S 2-0.023 9 S + 0.111 9,R2 = 0.922 8;DAP = 0.009 3 pH2-0.149 9 pH + 0.717 4,R2 = 0.976 8;DAP =-0.000 3 m3 + 0.011 1 m2-0.104 3 m + 0.362 8,R2 = 0.948 4.These results indicated that juvenile Nile tilapia cultured at desirable conditions as derived in the present study for the increase of the ability to withstand hypoxia.It is suggested that water temperature be maintained at 25.28 ℃,salinity at 3.6 and pH at 8.06 across the process of juvenile Nile tilapia culture when hypoxia happened.