The Bioaccumulation And The Effect Of Heavy Metals On The Jumping Performance Of Bufo

The decline of amphibian populations is an indisputable worldwide fact, and the environmental pollution is one of the reasons causing this phenomenon. At the same time, the toxic effect of environmental contamination, such as heavy metals, on the wildlife has attracted more and more attention. Several reports have reported the effect of heavy metals on animals’behavior, and there are some reports about the impact of heavy metals on the tadpoles’behavior in the lab. Those reports demonstrated that after being exposed to heavy metals, the activity and the swimming speed of the tadpoles decreased. However, there are few reports about the effect of heavy metals on the behaviour of adult amphibians in the field. Heavy metals in the environment could accumulate in the organisms and be magnified along the food chain, which may cause more toxic effect on the higher consumers in the ecosystem.Baiyin and Liuijaxia areas are both located at the upper reaches of the Yellow River in Gansu Province. Baiyin is mainly polluted by heavy metals while Liujiaxia is a relatively unpolluted area. The toad Bufo raddei is a common species found at the North of China. In the present study, the jumping performance of B. raddei from the two areas were tested, and the concentrations of heavy metals (Cu, Zn, Cd, Pb) in the skin, muscle, bone, liver, kidney, intestine and the whole body of the toad were tested by the dam-heat digestion and atomic absorption spectrophotometry methods. The structure of the toad’s gastrocnemius muscle fibers was observed by the paraffin sections. The activities of total-ATPase, Ca2+-ATPase and acetylcholinesterase (AChE) in the toad’s thigh muscle were also tested in order to study the effect of heavy metals on these enzymes and study the pathway of heavy metals affecting toads’jumping performance. The results showed that:1. The concentrations of heavy metals in the toad from Baiyin area were dramatically higher than that from Liujiaxia area, and the bioaccumulations in the tadpoles and juveniles were much higher than that in the adults. In B. raddei, Cu was mainly accumulated in liver, Zn mainly in skin, Cd mainly in kidney and Pb mainly in bone.2. The body lengths and heights of the toads from Baiyin area were lower than that from Liujiaxia area (P<0.05), but with higher deformity rates among the juveniles. The heavy metals in Baiyin area were responsible for the development inhibition and the high deformity of the toads.3. The jumping performance of the toads from Baiyin area was poorer than that from Liujiaxia area (P<0.01), suggesting that heavy metals affected the toad’s locomotor behavior. While the body length of toads from Baiyin area was decreased, indicating that body size would affect the toads’jumping performance at some degree. However, the relative jumping performance, which is the ratio of the jumping distance and the body length and could dispel the influence of body size, was also decreased in Baiyin area (P<0.05), suggesting that there are more important causes responsible for the decreasing of the toad’s jumping performance.4. The activities of total-ATPase, Ca2+-ATPase and AChE in the toad’s thigh muscle from Baiyin area all increased significantly (P<0.01). The activities of the enzymes were probably induced by the heavy metals in the environment.5. As showed by the paraffin sections of the toad’s gastrocnemius muscle, the muscle fibers of the toads from Baiyin region were damaged. This may be one of the main reasons causing the poor jumping performance of the toad.Smaller body size, higher rate of deformity and poorer jumping performance have adverse effect on the toad, which might in turn affect the toad’s other behaviors, such as prey-capturing, escaping from the predator and the mating success. As a result, the fitness of the species was decreased. In Baiyin area, the heavy metals induced the activities of the total ATPase, Ca2+-ATPase and AChE, suggesting that inhibition of the activities of enzymes was not the way to affect the jumping performance. The smaller body size and damage in the muscle may be the main reasons causing the poor jumping performance of the toad.