氨氮对大口黑鲈北方亚种引进种F1代幼鱼急性毒性及生理变化的影响

Effects of ammonia nitrogen on acute toxicity and physiological changes for introduction of Micropterus salmoides F1 juvenile

为探究急性氨氮胁迫对大口黑鲈(Micropterus salmoides)北方亚种引进种F1代幼鱼的生理适应性,以体质量(12.51±0.91)g的幼鱼为对象,进行氨氮胁迫试验。氨氮对其急性毒性试验结果显示:引进种F1代幼鱼24、48、72、96 h的总氨氮半致死浓度分别为33.66、29.86、26.98和25.08 mg/L,安全浓度为2.51 mg/L。通过18 mg/L浓度的氨氮溶液对其进行96 h的急性胁迫实验,结果显示:氨氮胁迫后鳃组织中Na^(+)/K^(+)-ATP酶活性随胁迫时间延长出现降低升高交替的现象,在12 h时达到最低值,48 h时达到最高值;肝和鳃组织中hsp70 mRNA表达量均呈先升高再降低的变化趋势,都在胁迫6 h时达到最大值,随后开始下降,肝组织下降速度快于鳃组织。48~96 h胁迫组肝和鳃组织hsp70 mRNA表达量均显著低于对照组。脑组织中hsp70 mRNA表达量在0 h时表达量最高,并随着时间的延长持续下降,在胁迫6 h时就显著低于对照组。结果表明,较高浓度的氨氮会引起大口黑鲈加州原种产生应激损伤,因此在实际养殖中要及时监测水体中氨氮浓度,避免造成经济损失。

The juveniles with a body mass of(12.51±0.91)g were used to test the acute stress effects of ammonia nitrogen to explore the physiological adaptability of acute ammonia nitrogen stress for the introduction of Micropterus salmoides F1 juvenile.Firstly,the acute toxicity test results of ammonia nitrogen showed that the median lethal concentration(LC_(50))of total ammonia nitrogen was 33.66 mg/L at 24 h,29.86 mg/L at 48 h,26.98 mg/L at 72 h,and 25.08 mg/L at 96 h,respectively.The safe concentration of total ammonia nitrogen was 2.51 mg/L.Secondly,the concentration of 18 mg/L ammonia nitrogen solution was used to carry out a 96-hour acute stress experiment.The results showed that Na^(+)/K^(+)-ATP ase activity in gill tissue decreased and increased alternately with the time of ammonia nitrogen stress.It reached the lowest value at 12 hours and the highest value at 48 hours.The expression of hsp70 mRNA in liver and gill tissues increased at first and then decreased after ammonia nitrogen stress,and reached the maximum at 6 h,then began to decrease,and the decrease rate of hsp70 mRNA in livers was faster than that in gills.The expression of hsp70 mRNA in livers and gills in the 48-96 h stress group was significantly lower than in the control group.However,the expression of hsp70 mRNA in brains was the highest at 0 h and decreased continuously with time,and was significantly lower than that in the control group at 6 h.The results showed that the higher concentration of ammonia-nitrogen could cause stress damage to the M.salmoides,so monitoring the concentration of ammonia-nitrogen in the water body to avoid economic loss is necessary.