Toxic Effects Of Copper And Cadmium Exposure On Chironomus Plumosus And Propsilocerus Akamusi

The present study was conducted to investigate the acute toxic effects of waterborne Cu and Cd exposure in Chironomus plumosus and Propsilocerus akamusi, and toxic effects of waterborne Cu and Cd exposure on antioxidant defense system and reproduction in Chironomus plumosus and Propsilocerus akamusi, in order to explore the relationship of heavy metal pollution and these indicators. The results were as follows:1. The optimization of culture sediment and space conditions on Chironomid larvaeWe studied the effects of different structures and thickness of sediment as well as different feeding space on the survival rate, pupation rate and eclosion rate of Chironomus plumosus larvae. The results showed that compared with the same specifications of clay, using the pond sediment as experimental sediment would get the highest survival and pupation rate, while the sediment particle size is0.15mm, the rates of survival and pupation would get higher; extra leaves would improve the survival and pupation rate of Chironomid larvae, but would also have some adverse effects to water quality. With the increasing of the sediment thickness, the survival rate and the number of nesting have significantly increased; appropriate feeding bait could improve the growth rate of Chironomid larvae.2. Toxic effects of waterborne copper and cadmium exposure on Chironomus plumosusThe acute toxicity of copper and cadmium to Chironomus plumosus was studied with the static test method in the laboratory. The results showed that the LC50values of96h for copper and cadmium to Chironomus plumosus were0.091and0.186g/L, respectively. The safe concentrations of copper and cadmium were0.0091g/L and0.0186g/L, respectively. In addition, the LC50values of96h for copper and cadmium decreased as the exposure time expended.The tissue oxidative stress responses of the copper and cadmium to Chironomus plumosus was studied by using the static-test method in this study; the experiment concentrations were set up at0.005,0.010,0.020g/L and0.020,0.040,0.060g/L according to the LC50, respectively. Superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) activities were monitored in all exposure groups at24h,48h,72h and96h. The induction of mouthpart deformities and the developmental response to copper exposure at three concentrations (0.005,0.010and0.020g/L) were investigated.We also set up a two-factor experiment,with animals exposed to four levels of cadmium(0.020,0.040and0.060g/L)at two feeding levels.The influence of the interaction of the two factors to the reproduction of Chironomus plumosus was also studied.The results showed that Cu2+had significant influenee on the activities of SOD and CAT,and such effects are significantly related to increased exposure dosage.GST activities increased significantly in all groups along wim the continuous hours and Cu2+concentrations after72h(P<0.05),and reached the highest after96h exposure(P<0.01). The result showed that there is a significant correlation between the percentage of total deformities and exposure concentration(P<0.05).The activities of SOD,CAT and GST reached the highest after48h cadmium exposure(P<0.01),followed by a decrease with the exposure time expended(P<0.05)ï¼›We also found that the length of larvae decreased with the increasing of the cadmium exposure concentrations, and was affected significantly by the food ration.In addition,there was no significant effect of cadmium exposure concentrations and food ration on the camulative emergence.3.Toxic effects of waterborne copper and cadmium exposure on Propsilocerus akamusiThe acute and joint toxicity of Cu2+,Cd2+,Zn2+and Mn2+to Propsilocerus akamusi were studied by static test method and equality toxicity method.The results showed that the LC50values of96h for Cu2+,Cd2+,Zn2+and Mn2+to Propsilocerus akamusi were0.209,0.767,1.738and0.276g/L,respectively.The safe coneentrations of Cu2+,Cd2+, Zn2+and Mn2+were0.0209,0.0767,0.1738and0.0276g/L,respectively.The joint toxicities of the four heavy metals were as follows:The low intensity of Mn2+and the high intensity of Cu2+,Cd2+and Zn2+were antagonisticï¼›while the high intensity of Mn2+and the low intensity of Cu2+,Cd2+and Zn2+were synergitic.The joint toxicity of cu2+-Cd2+and Cd2+-Zn2+to Propsilocerus akamusi changed from synergitic to antagonistic with the increasing eoncentrations of the formerï¼›the joint toxicity of Cu2+and Zn2+to Propsilocerus akamusi was synergitic.The tissue oxidative stress responses of the copper and cadmium to Propsilocerus akamusi were studied in this study;the copper and cadmium experiment coneentrations were set up at0.010,0.020,0.040,0.080g/L and0.050,0.100,0.200,0.400g/L, respectively.SOD,CAT and GST activities were monitored in all exposure groups at24h,48h,72h and96h.SOD CAT and GST activities increased significantly in high dose groups along with the continuous hours and Cu2+concentrations after24h (P<0.05), followed by a decrease after48h exposure, and got a continuous increase after72h. However, the SOD, CAT and GST activities in low dose groups did not change in the first48h, and were increased significantly after that (P<0.05).SOD activities did not have significant change in low dose groups, while increased significantly in high dose groups along with the continuous hours and Cd2+concentrations after72h (P<0.05, P<0.01), and decreased after96h exposure. the activities of CAT reached the highest after48h cadmium exposure, followed by a decrease with the exposure time expended (P<0.05). GST activities increased significantly in low dose groups along with the continuous hours and Cu2+concentrations, while in high dose groups increased significantly after48h (P<0.05).