Preserved riparian forest protects endangered forest-specialists amphibian species against the genotoxic impact of sunlight and agrochemicals

摘要

Although agrochemicals and solar ultraviolet (UV) radiation are both environmental stressors currently associated with amphibian decline, little is known about their interactive effects on amphibian larvae. One potential hazardous consequence of this interaction could be the increase of chromosomal damage and induction of cell death, which culminate in tadpole mortality. In this study, the preservation level of the riparian forest of four different streams located at the Atlantic Forest in southern Brazil was evaluated through satellite imagery analysis. The incidence of solar UVB and UVA radiation were measured with a radiometer in the amphibian breeding sites, and the presence of agrochemicals in the water was quantified through liquid chromatography coupled in tandem to mass spectrometry. Tadpole population density of two endangered forest-specialist amphibian species (Boana curupi and Crossodactylus schmidti) was evaluated in each stream, and the chromosomal damage of the collected larvae was determined through cytogenetic analysis of blood samples. The results clearly indicate that the preservation of riparian forest efficiently blocks the incidence of UV radiation upon the water surface and reduce by 2.7-fold the entry of agrochemicals from adjacent agricultural crops. Tadpoles collected in streams with preserved and continuous riparian forest presented a significantly lower amount of micronuclei, as well as higher population density in comparison to tadpoles collected in streams located in converted agricultural landscape. Therefore, this study demonstrates that the preservation of the riparian forest has paramount importance in reducing the impact of environmental genotoxic agents into lotic breeding sites used by forest specialist amphibian species.