How Antiepileptic Carbamazepine Affects the Aquatic System: Acute and Sublethal Toxicity on the Narrow-Clawed Crayfish Pontastacus leptodactylus (Eschscholtz, 1823).

Increasing prescription of the anticonvulsant medication carbamazepine (CBZ) is leading to significant environmental contamination, potentially posing serious health risks to freshwater aquatic species. Therefore, this study aimed to reveal the acute and sublethal toxic effects of CBZ exposure on the narrow-clawed crayfish. Following the acute toxicity of CBZ at 96-h LC50 of 125.5 mg/L, crayfish were exposed to sublethal concentrations of CBZ (12.5 and 1.25 mg/L) for 2, 7, and 14 days. At the end of the exposure periods, the total hemocyte counts of the crayfish decreased significantly after 2 and 7 days of CBZ exposure, while hemolymph total antioxidant status and total oxidative stress increased significantly after 7 and 14 days of CBZ exposure compared to controls (p < 0.05). In CBZ-exposed groups compared to controls, superoxide dismutase and glutathione peroxidase activities significantly increased in the gills and decreased in the hepatopancreas (p < 0.05). In the CBZ-exposed groups compared to controls, catalase activity increased in the hepatopancreas, while in the gills and muscles, it only increased at higher concentrations (p < 0.05). Malondialdehyde, however, increased in the gills and hepatopancreas at both CBZ concentrations (p < 0.05). In conclusion, sublethal concentrations of CBZ showed systemic and tissue toxic effects on crayfish by increasing oxidative stress and stimulating antioxidant mechanisms. It also supports a better understanding of the early detection of CBZ in aquatic species of freshwater ecosystems. The present study has resulted in a more profound comprehension of the early toxicological effects of CBZ in the freshwater species in aquatic ecosystems.