低温胁迫对许氏平鲉补偿生长的影响

Compensatory growth of rockfish (Sebastes schlegeli) following low temperature stress

以体质量(60±10)g、体长(13±2)cm的许氏平(Sebastes schlegeli)为研究对象,在8.5℃水体中低温胁迫1周(T1组)、2周(T2组)、3周(T3组)后在20℃水体中恢复3周,研究其补偿生长。结果表明,低温胁迫后,T1、T2、T3组体质量、生长率均显著低于对照组(C1组,20℃);随低温胁迫时间的延长,鱼体脂肪含量逐渐降低,水分含量则逐渐增加,蛋白含量、能值与对照组差异不显著。经低温胁迫1周后,鱼体溶菌酶、SOD、CAT活力比对照组略有下降,但随胁迫时间的延长,3种酶活力均呈上升趋势。经4周恢复生长后,T1、T2组鱼体各项生化组分及免疫酶活力均恢复至对照组水平,而T3组的鱼体脂肪、水分含量及免疫酶活力与对照组仍有显著差异,T1、T2组实现了完全补偿生长,而T3组只实现了部分补偿生长。从摄食率、食物转化效率的变化曲线可知,经低温胁迫后许氏平的补偿生长效应主要是通过提高食物转化效率实现的。[中国水产科学,2006,13(4):566-572]

Compensatory growth refers to the rapid growth spurt that follows a period of being exposed to undernutrition or other unfavorable environmental conditions, which result in the growth depression of animals. Compensatory growth has been reported in lots of animals, including fish. Most studies on compensatory growth in fish have dealt with just one of the possible causes of growth depression, namely, food shortage. Nevertheless, few studies have examined compensatory growth of fish after temperature stress. Therefore, in the present study compensatory growth of rockfish after different periods of temperaturestress was studied. The experiment lasted for 8 weeks and was divided into two periods, temperature stress period and recovery period. The control fish were kept at 20℃ throughout the experiment. Fish in other three groups were subjected to three periods of low temperature （8.5℃ ） stress as following： one week （group T1）, two weeks （group T2） and three weeks （group T3）. When the stress ended, the temperature of the three groups were increased gradually to 20℃ in a week and then were kept at 20℃ during the following 3 weeks. When the fish were held at 8.5℃ for more than 1 week, the lipid contents of the fish decreased, and water contents increased, while the protein and energy contents were not significantly different from the controls. After recovery at 20℃ for 3 weeks, all parameters of biochemical compositions of group T1 and T2 restored to those of the controls, but the lipid and water contents of group T3 were still significantly different from the controls. It indicated that after low temperature stress for one or two weeks, rockfish could achieve compensation in body composition after 4-week recovery, while after stress for more than two weeks, it could not compensate in this short period. At the end of low temperature-stress periods, the activities of lysozyme, SOD, CAT of group T1 were slightly lower than those of the controls. However, the three indexes of group T2 and T3 increased. When the recovery periods ended, the activities of lysozyme, SOD, CAT of group T1 and T2 had no significant differences from the controls, while group T3 were still significantly higher than the controls. It showed that the temperature stress could influence the immunity of rockfish. But after 4-week recovery, the immunity of fish subjected low level of temperaturestress （for one or two weeks） could return to that of the control fish. The body weight and specific growth rate （SGR） of stressed fish were significantly lower than the controls after stress. At the end of the recovery period, group T1 and T2 completely compensated and group T3 partly compensated the growth depression. By analyzing the data of feeding rate and food conversion efficiency during the recovery period, it was concluded that the compensatory growth of rockfish after low temperature-stress mainly depended on improving food conversion efficiency （FCE）. [Joumal of Fishery Sciences of China, 2006,13 （4） ： 566 - 572]