鲇幼鱼耗氧率与氨氮排泄率的初步研究

Oxygen consumption and ammonia excretion of juvenile oriental sheatfish Silurus asotus

采用实验生态学方法研究了温度和体重对鲇Silurus asotus幼鱼呼吸、氨氮代谢的影响。结果表明：鲇幼鱼耗氧率具有昼夜节律性,一昼夜在4：00-7：00和17：00-20：00各出现一个耗氧高峰,这两个时间段应是鲇幼鱼的摄食和活动高峰;在18-31℃下,鲇幼鱼的耗氧率随着温度的升高而增加,排氨率在18-26℃的条件下随着温度的升高而增加,高于26℃时随着温度的升高而减小;耗氧率（OR）和排氨率（N）均随着体重（W）的增加而下降,并呈幂函数的关系,相关方程分别为OR=0.8784W-0.9145（R2=0.9731）,N=34.665W-0.8999（R2=0.8616）;随着温度的上升,鲇幼鱼耐低氧能力下降,当温度大于26℃时,窒息点超过0.5 mg/L;随着体重的增加,鲇幼鱼耐低氧的能力上升,体重低于4.06 g时,窒息点没有显著差异（P〉0.05）,当体重达到11.06 g时,窒息点降至（0.319±0.031）mg/L,显著低于其他组（P〈0.05）。

The effects of temperature （ 18, 22, 26, and 30 ℃ ） and body weight on oxygen consumption and ammonia excretion were determined in juvenile oriental sheatfish Silurus asotus with body weight of （ 1.4 - 11.8 ） g by ecological methods in a laboratory. The sheatfish was found to have diurnal rhythm of oxygen consumption rate with the two oxygen consumption peaks at 4：00 - 7：00 and 17：00 - 20：00, parallel to feeding and activity. The oxygen consumption and ammonia excretion increased with the increase in water temperature between 18 ℃ and 31℃ and between 18 ℃ and 26 ℃ , reduced at the water temperature of 31℃. The oxygen consumption rate（OR） and ammonia excretion rate （N） decreased significantly as the body weight increased, the relationships being represented by the power equations OR = 0. 8784W^-0.9145 （ RE = 0. 9731 ） and N = 34. 665 W^-0.8999 （ R^2= 0. 8616 ） respectively. The suffocation point was found to decrease with the increase in water temperature, and the higher suffocation point （P 〉 0.5 mg/L） was observed at a water temperature of over 26℃. There was higher resistance to low oxygen level in the fish with higher body weight. For the suffocation point, however, there was no significant difference in the fish with body weight of less than 4.06 g（ P 〉0. 05 ）. A low suffocation point （0.319 mg/L ± 0.031 mg/L）, significantly lower than those in the other groups, was observed in the fish with body weight of 11.06 g.