A Study Of The Cross-effects Of Ultraviolet Radiation And Herbicides On Amphibians

Amphibians are facing a fatal threat.Due to the alteration and fragmentation of their natural habitats,amphibian individuals are more likely to be exposed to multiple environmental stressors than ever before.Besides,it is now considered that potential interactive effects between different stressors might be the primary reason for population decline.With the increasing chemical contaminants emitting into the environments,it becomes necessary to re-assess the interactive effects with other environmental factors.This study focuses on the ubiquitous ultraviolet radiation(UVR),studying the interactive effects with different chemical contaminants to the amphibians.The study is combined from two parts as follows.Published articles have been collected and reviewed,and data were extracted and standardized for further meta-analysis.The Independent Action model was applied to estimate the mixed effect of UVR and contaminants,and the result shows that the overall interactive effect is not significant.In the analysis,observations were classified into different groups according to chemical characteristics of contaminants,or different animal taxa.Heterogeneity between observations was confirmed to be relevant with different chemicals,rather than different taxa of amphibians,and hydrocarbons are the only group showing significant phototoxicity to amphibians.Embryos of albino Xenopus laevis and Pelophylax nigromaculatus were exposed to UVR and herbicides simultaneously.After the treatment,dead or malformed embryos were collected and counted,suggesting that there is a limited antagonistic toxic effect between UVR and herbicides,regardless of different species.After that,the tadpoles of the two animals were exposed to UV-B radiation and then treated with herbicide,and their survival conditions were observed,and morphological data were measured.The result shows a slightly additive effect between UVR and herbicides.Besides,it indicates that X.laevis is more likely to reduce the herbicide resistance after being exposed to UVR,compared with P.nigromaculatus;which meets the prediction basing on their characteristics of natural habitats.This result suggests that some phototoxicity effects originate from the UVR-induced damage to organisms,which can vary between species.