小龙虾潜在捕食下牛蛙蝌蚪对铅镉复合污染的响应研究

Behavior and stress response of Lithobates catesbeianus to Procambarus clarkii under combined stress of lead and cadmium

环境污染及外来入侵捕食者共存对两栖动物生存的影响及其响应的系统研究相对较少。以牛蛙蝌蚪为研究对象,设置铅镉复合4个处理浓度[对照CK、低(0.05 mg/L Pb+0.005 mg/L Cd)、中(0.1 mg/L Pb+0.01 mg/L Cd)、高(1 mg/L Pb+0.1 mg/L Cd)]构建室内控制实验,研究外来入侵种小龙虾存在下牛蛙蝌蚪体内铅镉积累情况及牛蛙蝌蚪作出的生理响应及表型可塑性变化。结果表明,高处理组蝌蚪身体铅含量显著高于对照及低处理(p<0.05),蝌蚪尾巴镉含量显著高于对照组。无小龙虾存在下,随着处理浓度增加,蝌蚪体内SOD活性显著增加(p<0.05)。铅镉胁迫下小龙虾降低了蝌蚪的摆尾次数,与对照组相比,处理第21 d,低、中、高处理组分别降低了8.22%、9.59%和19.18%;处理第21 d,高处理组蝌蚪的体长、体宽和体肌层厚与对照组相比分别减小25.40%、29.71%和31.83%。本研究表明,蝌蚪通过改变表型可塑性、降低活动能力来适应重金属污染及潜在捕食者造成的胁迫,为两栖动物的生存及保护提供了数据支持与科学依据。

There are relatively few systematic studies on the interactive effects of environmental pollution and invasive predators on adaptability of amphibians.In this study, Lithobates catesbeianus were used as research objects to investigate the effects of crayfish predation on the characteristics of tadpoles, including behavior, phenotypic plasticity, physiological response, and the accumulation of heavy metals.The results showed that in the condition with or without crayfish, the Pb concentration of the tadpoles treated with high treatment was significantly higher than that of the control and low treatment(p<0.05),and the tail Cd content was significantly higher than that of the control.In the absence of predators, SOD activity in tadpoles increased significantly with the increase of treatment concentration, and in the presence of predators in high treatment, SOD activity in tadpoles was significantly lower than that in the absence of predators(p<0.05).In the absence of predators, the body length, body width, body muscular thickness and tail length, tail width and caudate muscular thickness of tadpoles in the cadmium treatment group were not significantly different from those in the control group.In the presence of predators, the high treatment group was significantly lower than the control group.On the 21st day of treatment, the fresh weight of tadpoles in the treatment with or without predators was significantly different from that in the control group.With or without predators, the number of tadpoles swinging their tails in the high treatment group was significantly lower than that in the control group.On the 21st day, the number of tadpoles swinging their tails in the low, medium and high treatment decreased by 8.22%,9.59% and 19.18% respectively.Predators significantly increased the concentration of heavy metals and antioxidant levels in tadpoles.At the same time, predators under heavy metal stress affected tadpoles’ adaptability to environmental changes and reduced the number of tadpoles’ tail wagging, which decreased by 8.22%,9.59% and 19.18% in the low, middle and high treatment groups compared with the control group on the 21st day.After changing body length, body width and body muscle thickness, the high treatment group decreased by 25.40%,29.71% and 31.83% respectively, compared with the control group at the 21st day.In conclusion, tadpoles adapt to the altered habitat caused by heavy metal stress and predator interaction by changing phenotypic plasticity and decreasing mobility.The results of this study provide a scientific basis for the survival and protection of amphibians under interactive effects of the above two stresses.