Use of biomarkers in bullfrog tadpoles Aquarana catesbeiana (Shaw 1802) for ecotoxicological evaluation of Pirajibú River (São Paulo, Brazil)

Abstract This study focused on investigating the water quality in Pirajibú River, a relevant water body that flows through the industrial zone of Sorocaba (São Paulo/Brazil). Due to the limitations of assessing water quality based solely on standard physicochemical tests, an ecotoxicological approach was used to assess biomarker changes in the liver of bullfrog tadpoles (Aquarana catesbeiana). The animals were divided into groups and exposed to water samples collected upstream and downstream of the industrial zone. After 96 hours, the upstream group presented a decrease in the enzymatic activity of glutathione peroxidase (GPx) and superoxide dismutase (SOD) and an increase in the activity of catalase (CAT). For the downstream group, while a decreased activity was observed for SOD, an increase in CAT and glutathione S-transferase (GST) activities was stated. A decrease in lipid peroxidation (LPO) levels was observed in the downstream group, and increased carbonyl protein (PCO) levels in the upstream and downstream groups. Integrated Biomarker Response (IBR) revealed GSH and PCO as the most responsive biomarkers, despite no differences were noted between the groups. Regardless of whether the water quality standards of Pirajibú River were following Brazilian environmental legislation, the tadpoles presented high sensitivity when exposed to the water, even for a short period.