Living on the edge: agricultural land use increases genotoxic damage in amphibians on southern brazilian wetlands

Abstract

Southern Brazil is a key agricultural region in South America, where wetland ecosystems are increasingly impacted by irrigated rice cultivation. Amphibians are particularly sensitive to environmental contamination due to their permeable skin and biphasic life cycle, making them effective bioindicators of ecosystem health. This landscape forms a mosaic of croplands and natural habitats, exposing wildlife to agrochemical contamination. In this study, we evaluated erythrocyte nuclear abnormalities (NAs) in the arboreal amphibian Dendropsophus sanborni and the aquatic amphibian Pseudis minuta, both inhabiting natural and agricultural wetlands in southern Brazil. Our results revealed significantly higher frequencies of NAs in individuals from agricultural environments across all evaluated biomarkers, indicating a generalized increase in genomic instability. Both micronuclei (MN) and nuclear abnormalities excluding MN (ENAs) increased in agricultural areas, reflecting different dimensions of genotoxic stress. Pseudis minuta consistently exhibited higher frequencies of abnormalities than D. sanborni and showed stronger responses to habitat type, highlighting the role of ecological traits and exposure pathways in modulating susceptibility to contaminants. Temporal variation was observed for several biomarkers, with higher frequencies occurring during periods coinciding with the onset of agricultural activities. These findings demonstrate that agricultural intensification promotes widespread cellular damage in wetland amphibians and emphasize the importance of integrating multiple biomarkers and species with contrasting ecological traits in biomonitoring programs. Such approaches are essential to improve the detection of sublethal effects of agrochemical exposure and to support conservation strategies in agricultural landscapes.