摘要：
Juvenile spiny eel Mastacembelue armatus (Lacepe'de,1800) with body weight of (1.39 ± 0.60) g was exposed to ammonia nitrogen prepared by NH4Cl (un-ionized ammonia) at concentration of 0 (control) mg/L,37 (2.26) mg/L,42 (2.56) mg/L,49 (2.99) mg/L,56 (3.42) mg/L,65 (3.96) mg/L,75 (4.57) mg/L,87 (5.31) mg/L and 100 (6.10) mg/L and nitrite prepared by NaNO2 at concentration of 0 mg/L (control),0.49 mg/L,0.65 mg/L,0.75 mg/L,0.87 mg/L,1.15 mg/L,1.55 mg/L and 2.10 mg/L to evaluate the acute toxicity of ammonia nitrogen and nitrite to the juvenile at dissolved oxygen level of (5.0～6.0) mg/L,pH of (8.0～8.2) and water temperature of (27.0～28.0)°C by a acute toxicity method.The results showed that the median lethal concentration (LC50) of total ammonia nitrogen on spiny eel juveniles was 78.35 mg/L at 24 h,77.15 mg/L at 48 h and 76.05 mg/L at 96 h,and that the LC50 ofun-ionized ammonia on the juveniles 4.78 mg/L at 24 h,4.71 mg/L at 48 h and 4.64 mg/L at 96 h.The LC50 of nitrite on the juveniles was found to be 1.177 mg/L at 24 h,0.921 mg/L at 48 h and 0.798 mg/L at 96 h.The safe concentration was found to be 7.61 mg/L for total ammonia nitrogen,0.46 mg/L for un-ionized ammonia,and 0.0798 mg/L for nitrite,indicating that the acute toxicity of nitrite is stronger than ammonia nitrogen for the juveniles.The findings indicate that juvenile spiny eel is more sensitive to the toxicity of nitrite compared with other fishes and that the changes in nitrite concentration should be paid more attention in breeding of spiny eel juveniles.%依照水生生物毒性方法,在溶解氧5.0～6.0mg/L、水温27.0～28.0°C、pH8.0～8.2条件下,用分析纯NH4Cl和NaNO2配制成总氨氮(非离子氨)浓度为0(对照组)、37(2.26)mg/L、42(2.56)mg/L、49(2.99)mg/L、56(3.42)mg/L、65 (3.96)mg/L、75 (4.57)mg/L、87 (5.31)mg/L和100 (6.10)mg/L,亚硝酸盐浓度为0mg/L(对照组)、0.49mg/L、0.65mg/L、0.75mg/L、0.87mg/L、1.15mg/L、1.55mg/L和2.10 mg/L,研究氨氮和亚硝酸盐浓度对平均体质量(1.39±0.60)g的大刺鳅Mastacembelue armatus幼鱼的急性毒性.结果表明:大刺鳅幼鱼总氨氮的24h、48h和96h半致死浓度分别为78.35mg/L、77.15mg/L和76.05mg/L,非离子氨半致死浓度分别为4.78 mg/L、4.71mg/L和4.64mg/L,亚硝酸盐半致死浓度分别为1.177mg/L、0.921mg/L和0.798mg/L,总氨氮、非离子氨和亚硝酸盐的安全浓度分别为7.61mg/L、0.46mg/L和0.0798mg/L.亚硝酸盐对大刺鳅幼鱼的急性毒性强于氨氮,对亚硝酸盐的毒性也比其他鱼类更敏感,在生产中应特别注意监控水体中亚硝酸盐浓度的变化.
