Population Dynamic Of Aquatic Arthropods In Outdoor Microcosms:Impacts Of Chlorpyrifos Indicated By Free-living NAGase

As a substitute of high toxic pesticides, chlorpyrifos has frequently been applied in paddy field, and the consequent environmental problems are therefore getting more and more attention. In this research, the inhibition and recovery of aquatic community and the effects of chlorpyrifos on water quality were studied by the macrophyte-dominated outdoor microcosm (500L) which was taken as a tool. Meanwhile, the activity of free β-N-Acetyl-D-glucosaminidase (NAGase, EC3.2.1.52) and immunoreactive NAGase protein were detected so as to analyse the application of them in biomass evaluation of aquatic arthropod.According to PRC of influence on aquatic arthropods under chlorpyrifos, the results showed that chlorpyrifos caused a significant decrease in aquatic arthropods. The smallest NOECcommunity calculated by Williams test using the PCA score was0.2μg/L when expressed in terms of the nominal treatment level in this research, effects on microcosms were not observed at this concentration; when the concentration increased to1.8μg/L, the inhibition was appeared only on21d and28d; the effects were dissappeared on35d under the concentration of16.2μg/L and when the microsocms were exposed to145.8μg/L, the inhibition effects were last for85d, while there was no recovery at the end of the study under the concentrationof1312.2μg/L.Correlation between the activity of free NAGase in the water and biomass of aquatic arthropods were uncovered (R2=0.5798). Polyclonal antibody of NAGase from Daphnia magna and Chironomus kiiensis was employed to detected contents of NAGase-IR, according to the non-competitive ELISA. The total NAGase-IR were used to evaluate the biomass of aquatic arthropod, the linear equation was Y=375.73X+34.13, R2=0.6657. These data indicated that the free NAGase could be employed to monitor dynamics of the outdoor biotic population, and ELISA had better reflection on the aquatic arthropod as well. When the effects were reflected with NAGase activity and NAGase-IR contents, the results of the NAGase-IR contents were similar with the traditional methods, which means that theNAGase-IR would be better to reflected the changes of aquatic arthropods.