中文摘要：

采用人工受精获得的南方鲇 Silurus meridionalis Chen胚胎和仔鱼为实验对象，以Pb（NO3）2为毒物源，在水温22.5℃条件下，观察了水体中不同质量浓度铅（Pb）暴露对南方鲇胚胎孵化率、畸形率、自主运动、孵化历时的影响，并进行了初孵仔鱼的Pb暴露毒理实验．实验结果表明，在水体中Pb2＋质量浓度分别为0（对照），4，8，12和16 mg／L的条件下，南方鲇胚胎孵化率随着Pb质量浓度的上升呈下降趋势，分别为84.94％，71.23％，69.75％，66.57％和64.69％，各Pb质量浓度处理组的孵化率显著低于对照组（ p＜0.05）；且孵出的仔鱼出现心包水肿，脊柱弯曲以及尾巴弯曲退化等畸形特征，畸形率随着 Pb质量浓度的升高呈上升趋势，分别为10.27％，15.28％，22.28％和36.67％，各Pb暴露组均显著高于对照组（2.37％）（ p＜0.05）；各Pb质量浓度暴露组胚胎在出膜前期的自主运动频率分别为63.86，52.71，48.43和47.14次／min均显著低于对照组（78.00次／min）（p＜0.05）；各Pb质量浓度暴露组的胚胎孵化历时均显著长于对照组（p＜0.05）．孵化后在净水（未加入Pb（NO3）2的实验水体）中养殖的卵黄囊期仔鱼72 h死亡率随着其胚胎期Pb暴露质量浓度的上升呈上升趋势，胚胎期Pb暴露质量浓度分别为0，4，8，12和16 m g／L的条件下，仔鱼期的净水死亡率分别为9.45％，18.22％，20.95％，24.05％和26.29％，胚胎期各Pb质量浓度暴露组所获仔鱼的死亡率均显著高于对照组（ p＜0.05）．根据水体 Pb暴露对南方鲇初孵仔鱼急性中毒致死的观测结果推算，其96 h半致死质量浓度（96 h LC50）为0.32 mg／L ．本研究结果表明，南方鲇胚胎对水体Pb暴露的耐受性高于其初孵仔鱼，可能与南方鲇的受精卵卵膜较厚，对水体中的Pb2＋进入胚胎具有较大的阻滞作用有关．

英文摘要：

To determine the toxic effects of waterborne Lead （Pb） on embryonic and larval development of the southern catfish （Silurus meridionalis Chen） ,the embryos and larvae which have been bred with arti-ficial fertilization have been exposed to Pb solutions of five nominal concentrations （0 ,4 ,8 ,12 and 16 mg/L） at 22 .5℃ respectively .Embryonic hatching rate ,larval malformation rate ,spontaneous movements , incubation period have been evaluated at the end of embryonic period . Acute toxicity of Pb to newly hatched larvae has also been determined in this study .Embryonic hatchability has decreased with the in-creasing Pb concentration .The value in the groups of 4 ,8 ,12 and 16 mg/L were 71 .23% ,69 .75% ,66 .57%and 64 .69% respectively ,which are significantly lower compared with the control group （84 .94% ） （p〈0 .05） .Furthermore ,exposure of embryos to Pb has significantly increased morbidity of body malforma-tions in newly hatched larvae ,such as pericardial edema ,body curvature and degenerated tail .In the groups of 4 ,8 ,12 and 16 mg/L ,the malformation rate of newly larvae are 10 .27% ,15 .28% ,22 .28%and 36 .67% respectively ,which are significantly lower than that of the control group （2 .37% ） （p〈0 .05） .The average spontaneous movements of embryos decreased along the contamination gradient .In the concentrations of 4 ,8 ,12 and 16 mg/L ,the value are 63 .86 ,52 .71 ,48 .43 and 47 .14 beats/min , which are significantly lower compared with the control group （78 .00 beats/min） before hatching （44 hours post-fertilization） （p〈0 .05） .Pb also has an inhibitory effect on hatching time .The incubation peri-ods are significantly delayed compared to control （p〈0 .05） .Exposures to waterborne Pb during embryon-ic period alone causes adverse impact on larval performance even w hen larval development took place in clean w ater .And the lowest larval mortality in 72 hours after hatching occurred in the control group （9 .45% ） , which is significantly lower th