Estimation Of LC50 And Behavioral Modifications Of Cyprinus Carpio (L.) In Response To Isoproturon Herbicide

Abstract

Isoproturon, a widely used Phenyl urea group herbicide for controlling weeds in cereal crops, frequently enters aquatic environments through agricultural runoff, posing risks to non-target species. This study examines the behavioral and morphological responses of Cyprinus carpio (L.), the common carp fingerlings following exposure to sub-lethal herbicide concentrations of the Isoproturon (75% WP). C. carpio was exposed to different concentrations of Isoproturon (0.10–0.200 mg/L) for 96 hours, with the median lethal concentration (LC₅₀) determined at 0.160 mg/L using a semi-static bioassay. Based on this value, two sub-lethal concentrations 0.0224 mg/L (1/7^th of LC₅₀) and 0.0112 mg/L (1/14^th of LC₅₀) were selected for subacute exposure studies lasting 1, 7, and 14 days. After the 14-day exposure period, the fish were transferred to a toxicant-free medium for a 7-day recovery phase. Exposed fish exhibited behavioral abnormalities, including erratic and darting swimming patterns, hyperactivity, loss of equilibrium, and a tendency to remain at the bottom. Morphological deformities, like caudal bending, discoloration of the body, and ocular disorders were observed throughout the exposure period. Although no significant mortality occurred at sub-lethal concentrations. Importantly, behavioral and morphological impairments persisted even after the recovery phase, indicating the long-lasting neurotoxic effects of Isoproturon. These results underscore the ecological threats posed by Isoproturon contamination in aquatic ecosystems, emphasizing the need for regulatory control and environmental monitoring to minimize its impact on aquatic life.