Immobilization, oxidative stress and antioxidant response of Daphnia magna to Amoxicillin and Ciprofloxacin

Abstract

Amoxicillin (AMX) and ciprofloxacin (CPX) are broad-spectrum antibiotics with wide application in agriculture and human and veterinary medicine. The drugs end up in the environment where their impact on zooplankton remains scantily understood. This study investigated the immobilization, risk assessment (RQ), antioxidant response, and biochemical changes of Daphnia magna post-exposure to AMX and CPX. Sixty-percent immobilization of Daphnia occurred at 200 μg L^-1 AMX and CPX, while EC₅₀ values were 2391.6 μg L^-1 and 273.4 μg L^-1, respectively. RQs were 113.3 and 11,481.5, while Toxic units were 41.6 and 364.9 for AMX and CPX, respectively. Both antibiotics caused a significant rise in intracellular hydrogen peroxide 48 h post-exposure, indicating oxidative stress. Lipid peroxidation and antioxidant enzyme activity were considerably altered during the research. Thus, environmentally relevant concentrations of AMX and CPX pose an adverse risk that could change the population dynamics of Daphnia magna.

Keywords: Amoxicillin; Antibiotics; Ciprofloxacin; Daphnia magna; Risk assessment.