温度对马口鱼幼鱼耗氧率、窒息点及抗氧化能力的影响

Effects of Temperature on Oxygen Consumption Rate,Suffocation Threshold,and Antioxidant Capacity of Juvenile Chinese Hooksnout Carp Opsariichthys bidens

为探讨不同养殖环境下2种规格的马口鱼幼鱼的耗氧率、窒息点和抗氧化指标,测定20、24、28℃3个温度梯度下2种规格马口鱼幼鱼的耗氧率、窒息点,以及正常溶解氧与低氧环境下的抗氧化指标。试验结果显示:马口鱼幼鱼的耗氧率和窒息点随温度升高呈先升后降趋势,小规格(1.22±0.31)g幼鱼20℃水温时的耗氧率和窒息点分别为(0.185±0.057)mg/(g·h)和(1.149±0.110)mg/L,显著低于24℃和28℃时的耗氧率和窒息点(P<0.05),24℃时(1.22±0.31)g幼鱼的窒息点显著高于28℃时的窒息点(P<0.05),但耗氧率无显著差异(P>0.05);大规格(4.91±0.55)g幼鱼在3个温度梯度下的耗氧率表现为24℃>28℃>20℃,而窒息点为28℃>24℃>20℃;水温28℃条件下,2种规格幼鱼耗氧率差异不显著(P>0.05);低氧胁迫下,马口鱼幼鱼肝脏组织的超氧化物歧化酶活性、丙二醛含量和总抗氧化能力显著升高(P<0.05),(4.91±0.55)g马口鱼幼鱼肝脏超氧化物歧化酶活性和总抗氧化能力高于(1.22±0.31)g幼鱼(P<0.05)。试验结果表明,(1.22±0.31)g马口鱼幼鱼对环境的适应能力低于(4.91±0.55)g马口鱼幼鱼,在低氧胁迫和温度胁迫下更易受到损伤。

In order to explore the oxygen consumption rate,suffocation threshold,and antioxidant index of two sizes of juveniles Chinese hooksnout carp Opsariichthys bidens in different cultural environments,the oxygen consumption rate,suffocation point,and anti-oxidation indices of Chinese hooksnout carp were determined under three temperature gradients of 20,24 and 28℃.It was found that the oxygen consumption rate and suffocation point of the juveniles was increased first and then decreased with increasing temperature.The oxygen consumption rate and suffocation point of small-sized juveniles(1.22±0.31)g at 20℃were(0.185±0.057)mg/(g·h)and(1.149±0.110)mg/L,significantly lower than the consumption at 24℃and 28℃(P<0.05).The suffocation threshold of small-sized juveniles was significantly higher at 24℃than that at 28℃(P<0.05),but there was no significant difference in oxygen consumption rate(P>0.05);the oxygen consumption rate of large-sized juveniles(4.91±0.55)g under three temperature gradients was 24℃>28℃>20℃,and the suffocation point was 28℃>24℃>20℃.Under the condition of 28℃,there was no significant difference in the oxygen consumption rate of two kinds of juvenile fish(P>0.05).Under hypoxia stress,the superoxide dismutase(SOD)activity,malondialdehyde(MDA)content,and total antioxidant capacity(T-AOC)in liver tissues of the juvenile were significantly increased(P<0.05),and the SOD activity and T-AOC content of the liver of the juvenile were higher than those of the small ones(P<0.05).The findings indicate that the adaptability of small-sized juveniles to the environment is lower than that of large-sized juveniles,and they are more susceptible to damage under hypoxia and temperature stress.