低盐度下亚硝酸盐暴露对凡纳滨对虾毒性与抗氧化能力的影响

Effects of low-salinity nitrite exposure on the toxicity and antioxidant ability in Pacific white shrimp Litopenaeus vannamei

摘要:

为探究低盐度条件下亚硝酸盐对凡纳滨对虾急性毒性及其氧化应激程度的影响，在盐度为1的水体中进行凡纳滨对虾亚硝酸盐急性毒性试验，测定4 mg/L和8 mg/L亚硝酸盐暴露和换水恢复期间对虾抗氧化指标，以及恢复24 h后对虾存活率、蜕壳率、摄食时间。结果表明：盐度1时，亚硝酸盐对凡纳滨对虾24、48、72和96 h LC50(半致死浓度)分别为15.96、9.97、7.54和5.25 mg/L，安全浓度 ( SC ) 为0.53 mg/L；经不同浓度亚硝酸盐胁迫后，对虾血淋巴超氧化物歧化酶 ( SOD ) 活性升高，显著高于0 h ( P < 0.05 ) ；8 mg/L亚硝酸盐处理3、6 h，肝胰腺SOD 活性显著高于4 mg/L 组( P < 0.05 )。血淋巴和肝胰腺谷胱甘肽过氧化氢酶 ( GSH-PX ) 活性升高， 8 mg/L亚硝酸盐处理6 h GSH-PX活性显著高于4 mg/L 组 ( P < 0.05 )。血淋巴过氧化氢酶 ( CAT ) 活性下降，4 mg/L 亚硝酸盐处理6、24 h后CAT活性显著低于0 h ( P < 0.05 )，肝胰腺CAT活性呈现波动，24 h CAT活性显著高于0 h ( P < 0.05 )， 8 mg/L亚硝酸盐处理24 h后CAT活性显著高于4 mg/L 组 ( P < 0.05 )。转移至正常养殖水体24 h后 ( F24 )，肝胰腺丙二醛 ( MDA ) 含量仍显著高于0 h ( P < 0.05 )，8 mg/L亚硝酸盐处理组MDA含量显著高于4 mg/L组 ( P < 0.05 )；与原水对照组比较，4和8 mg/L组对虾( F24 ) 存活率下降，蜕壳率显著升高 ( P < 0.05 )，摄食时间显著延长 ( P < 0.05 )，其中8 mg/L组 ( F24 )存活率显著低于4 mg/L组 ( F24 ) ( P < 0.05 )，而摄食时间显著大于4 mg/L组 ( F24 ) ( P < 0.05 )。研究表明，在低盐度养殖水体中，亚硝酸盐毒性较强，显著影响对虾抗氧化能力。低盐度条件下，为确保养殖对虾健康，应将亚硝酸盐浓度控制在0.53 mg/L以内。

Abstract:

In order to evaluate the acute toxicity and stress of nitrite on L. vannamei in low salinity, the acute toxicity of nitrite on L. vannamei, changes in antioxidant indicators of shrimps during n itrite (4, 8 mg/L) exposure and recovery periods, and the survival rate, molting rate, and feeding time of shrimps 24 h after recovery were measured at a salinity of 1 . Results showed that the 24, 48, 72, and 96 h LC50 of nitrite on L. vannamei were 15.96, 9.97, 7.54, and 5.25 mg/L, respectively, with a safe concentration ( SC ) of 0.53 mg/L. After exposure to different concentrations of nitrite, the activity of SOD in the hemolymph of shrimp increased, and was significantly higher than that at 0 h (P < 0.05) , the activity in the hepatopancreas of shrimps treated with 8 mg/L nitrite for 3 and 6 h was significantly higher than that in the 4 mg/L group (P < 0.05). The GSH-PX activity in hemolymph and hepatopancreas increased, and the activity in the 8 mg/L group was significantly higher than that in the 4 mg/L group at 6 h (P < 0.05). The CAT activity in the hemolymph decreased and was significantly lower in the 4 mg/L group at 6 and 24 h than that at 0 h (P < 0.05), the activity in the hepatopancreas fluctuated and was significantly higher at 24 h than at 0 h (P < 0.05) , and the activity was significantly higher at 24 h after shrimp treated with 8 mg/L nitrite than that in the 4 mg/L group (P < 0.05). After shrimps were transferred to normal culture water for 24 h (F24), the MDA content in the hepatopancreas was still significantly higher than that at 0 h (P < 0.05), and the content in the 8 mg/L group was significantly higher than that in the 4 mg/L group (P < 0.05); shrimps in 4 and 8 mg/L groups (F24) showed a decrease in survival rate, a significant increase in molting rate (P < 0.05) and a significant extension in feeding time (P < 0.05) compared with the control group. The survival rate in the 8 mg/L group (F24) was significantly lower than that in the 4 mg/L group (F24) (P < 0.05), while the feeding time was significantly greater than that in the 4 mg/L group (F24) ( P < 0.05). These findings suggest that in low-salinity aquaculture water, nitrite toxicity is strong, which has a significant impact on the antioxidant function of shrimps. Under low salinity conditions, to ensure healthy aquaculture, the concentration of nitrite should be controlled within 0.53 mg/L.