Lethal and sublethal effects of the emerging contaminant oxytetracycline on the embryo-larval development of Rhinella arenarum

The antibiotic oxytetracycline (OTC) is commonly used in animal production and can enter aquatic ecosystems, causing adverse effects on non-target species. The aim of this work was to evaluate the lethal and sublethal effects of OTC on the embryonic and larval period of Rhinella arenarum, through standardized bioassays and oxidative stress (catalase-CAT-, superoxide dismutase-SOD-, glutathione S-transferase-GST-, reduced glutathione GSH-and lipid peroxidation-TBARS-), neurotoxicity (acetylcholinesterase-AChE-and butyrylcholinesteraseBChE-) and genotoxicity (micronuclei test) biomarkers. Mortality was time and stage dependent, being the embryos (504 h-LC50 = 64.04 mg/L) more sensitive than the larvae (504 h-LC50 = 97.74 mg/L). Alterations in the oxidative stress biomarkers were observed mainly in larvae: CAT, SOD and GST decreased and GSH increased significantly. In embryos, only GST decreased significantly. Also, OTC increased the AChE and BChE activities but did not increase the micronuclei frequency. This study shows evidence that the presence of OTC in the environment may have negative effects on amphibians.

Automated summary

The presence of oxytetracycline in the environment has negative effects on the embryos and larvae of Rhinella arenarum, primarily through oxidative stress and neurotoxicity.