吉富罗非鱼对低温持续胁迫的死亡反应

为探讨罗非鱼对不同低温胁迫及其持续期的耐受性,采用人工降温持续胁迫吉富罗非鱼,统计不同低温协迫致死亡历时。结果表明：7.0、8.0、9.0、10.0℃低温持续胁迫条件下,吉富罗非鱼的半致死历时分别为12.25、17.00、25.00和31.50 h（P〈0.05）,即持续低温胁迫水平越低,半致死历时越短;而相同低温胁迫持续期内,温度越低,死亡率越高。拟合低温持续胁迫下吉富罗非鱼死亡率和死亡历时的回归方程,发现在7.0、8.0℃持续胁迫下,死亡率与死亡历时呈幂函数相关,分别为y=0.0024x^2.2453（R^2=0.9667）和y=0.0013x^2.0554（R^2=0.9516）;在9.0、10.0℃持续胁迫下,死亡率与死亡历时呈线性相关,分别为y=0.0552x-0.6854（R^2=0.9535）和y=0.0288x-0.2875（R^2=0.9523）。

Lethal reaction of Nile Tilapia (Oreochromis niloticus) under low temperature stress

The present experiment was conducted to study the tolerance of Nile Tilapia to low temperature stress and its duration.Nile Tilapia was continuously stressed by artificial decreasing temperatures and the lethal time of Nile Tilapia under different low temperature stress was recorded.The results showed that the semi-lethal duration of Nile Tilapia was 12.25,17.00,25.00 and 31.50 h（P0.05） under low temperatures of 7,8,9 and 10℃,respectively.That is,the semi-lethal du-ration decreased with decreasing temperatures,however,the mortality of Nile Tilapia was higher at lower temperature stress.The regression equation between death duration and mortality of Nile Tilapia was y =0.0024x^2.2453（R^2 =0.9667） and y = 0.0013x^2.0554（R^2=0.9516） at 7 and 8℃,respectively.While it showed linear correlation at 9 and 10℃ temperatures,and the e-quation was y=0.0552x-0.6854（R^2=0.9535） and y=0.0288x-0.2875（R^2=0.9523）,respectively.