【作者】 赵海涛；

【导师】 张其中；

【作者基本信息】 西南大学 ， 水生生物学， 2006， 硕士

【摘要】 本文研究了氨氮这一环境因子对南方鲶（Silurus meridionalis Chen）幼鱼的影响。通过急性氨氮毒性实验得出南方鲶幼鱼在24、48、72、96h的半致死浓度(LC₅₀)分别为182mg 1^-1TAN(2.8mg 1^-1,NH₃-N),171mg 1^-1TAN(2.7mg 1^-1,NH₃-N),151.4mg 1^-1TAN(2.4mg 1^-1,NH₃-N)和123mg 1^-1TAN(1.9mg 1^-1,NH₃-N),安全浓度为46.6mg 1^-1TAN(0.7mg 1^-1,NH₃-N)。半致死浓度随氨氮暴露时间延长呈下降趋势。 在慢性毒性实验中,把南方鲶幼鱼随机分成5个氨氮浓度组(150、120、90、60、30mg 1^-1)和一个对照组。分别在氨氮暴露处理的第4、7、14、21天取样,每个浓度组每次取样4尾,进行红细胞计数（RBC）、白细胞分类计数（DLC）、血红蛋白（Hb）、血糖（GLU）、总蛋白（TP）、白蛋白（ALB）、谷丙转氨酶（ALT）、谷草转氨酶（AST）、碱性磷酸酶（ALP）、抗菌活力、超氧化物歧化酶（SOD）、过氧化物酶（POD）、酚氧化物酶（PO）等指标的测定。利用统计软件SPSS 11.0和Excel 2003对数据进行分析,结果表明: 在高浓度氨氮暴露下,南方鲶幼鱼的红细胞数量、血红蛋白含量、红细胞压积和血清蛋白含量随着浓度升高和暴露时间延长而出现不同程度的下降。血糖浓度在暴露初期呈现先升高后下降趋势,在第7天,各个浓度组的血糖含量都出现显著升高（P<0.05）,至第21天,各个浓度组都出现了下降,高浓度组出现显著下降（P<0.05）。表明实验对象造血机能受损,机体携氧能力下降,造成机体组织缺氧,这可能是氨氮急性中毒引起死亡的主要原因。 经过21天的氨氮处理,血清谷丙转氨酶、谷草转氨酶、碱性磷酸酶活性呈现不同程度的升高,其中谷丙转氨酶和碱性磷酸酶活性更易受氨氮处理的影响而呈现显著性升高（P<0.05）,血清蛋白含量显著下降,表明机体内脏器官出现不同程度的损伤。 氨氮对非特异性免疫指标超氧化物歧化酶、过氧化物酶、酚氧化物酶、抗菌活力有抑制作用,只有在第4天,30和60mg 1^-1浓度组中的超氧化物歧化酶和过氧化物酶出现显著性升高（P<0.05）。随着暴露时间延长,酶的活性受到不同程度抑制,到第21天时,高浓度组(90、120、150mg 1^-1)呈现显著下降（P<0.05）。氨氮处理也会影响白细胞分类计数。在第7天,低浓度组(30、60、90mg 1^-1)更多还原

【Abstract】 This article investigated the effect of the environmental factor, TAN, on juvenile Southern catfish （Silurus meridionalis Chen）. The 24-,48-,72-,96-h medial lethal concentrations （ LC50） of ammonia-nitrogen for the juvenile catfish were 182 mg l^-1 TAN (2.8mg l^-1 , NH3-N), 171 mg l^-1 TAN (2.7 mg l^-1 , NH₃-N), 151.4 mg l^-1 TAN (2.4 mg l^-1 , NH₃-N) and 123 mg l^-1 TAN (1.9 mg l^-1 , NH₃-N), which were determined by a series of acute toxic trials. The safe concentration of TAN for the juvenile catfish is 46.6 mg l^-1 TAN (0.7 mg l^-1 , NH₃-N). It was found that LC₅₀ declined with time.In chronic poisoning experiment, the individuals of juvenile southern catfish were randomly divided into five groups subject to different concentrations of TAN, i.e., 150mg l^-1, 120mg l^-1, 90mg l^-1, 60mg l^-1, 30mg l^-1 plus a control. Changes of the parameters , namely, red blood cells （RBC）, differential leucocyte cells （DLC）, haemoglobin （Hb）, blood glucose （GLU）, total protein （TP）, albumin （ALB）, alamine aminotransferase （ALT）, aspartate aminotransferase （AST）,alkaline phosphatase （ALP）, antibacterial activity, superoxide dismutase （SOD）, peroxidase （POD）, phenoloxidase （PO） of the catfish blood, were measured on the 4, 7, 14, 21th day after the juvenile catfish were exposed to 0、 30、 60、 90、 120、 150 mg l^-1 total ammonia-nitrogen （TAN）, respectively. Then the data were analyzed with statistic software SPSS（11.0） and Excel （2003 ） . The results were as follows:When the juvenile southern catfish were exposed to high concentrations of TAN, RBC, HCT and Hb of the catfish declined with increased concentrations and extended exposure span. Blood glucose increased in early stage and then declined as exposure extended;GLU in all groups increased significantly （P<0.05） on Day 7 and declined on Day 21, especially in groups with a high concentration treatment (150mg l^-1) （P< 0.05）. The results suggested damage of experimental animals’ hematopoiesis and a decline of their capability of oxygen transportation, which may be the main reasons of fish death caused by acute TAN toxicity.After 21 days of treatment with TAN, the activity of ALT, AST and ALP all increased by different margins, the activity of ALT and ALP increased significantly, which may imply they are more vulnerable to TAN treatment. Those data demonstrated adverse effects of ammonia on serum protein and showed that interior organs of the catfish treated in a series of TAN concentrations may be damaged to some extent.TAN inhibited such non-specific indices as SOD, POD, PO, antibacterial activity. Only on Day 4 that SOD and POD increased significantly in the groups subjected to 30 and 60mg I’1 TAN. Activity of enzymes was inhibited when the exposure time extended and it significantly decreased on Day 21 in high-concentration TAN treatment groups （90, 120, 150mg I’1）. TAN treatment also affected DLC. Lymphocyte percentage of southern catfish in low level （30, 60, 90mg 1"’） TAN groups increased significantly and then declined on Day 7 whereas those in low level （30, 60, 90mg I"1） TAN decreased significantly （P<0.05） on Day 14 and 21. Neutrophils changed likewise. The indices were closely related with fish’s ability of oxidation resistance and immunity and their decline revealed a decrease in injury resistance and damage to immunity of the juvenile catfish after long-term exposure to TAN, as may be themain reason why fish exposed to TAN were more susceptible to other diseases.更多还原