Assessment of the acute toxicity of the organochlorine pesticide endosulfan in Cichlasoma dimerus (Teleostei, Perciformes)

摘要

The organochlorine insecticide endosulfan (ES) is widely used despite its high toxicity to fish (96-h LC-50 median value of 2.6 μg L~-1). This study aimed to assess the acute toxicity, histological and physiological parameters after exposure to 0; 0.25; 1; 2; 3; 4 and 16 μg L~ -1 ES for 96 h under semi-static conditions in a freshwater perciform fish, Cichlasoma dimerus. Prior to death, fish exhibited behavior indicative of neurotoxicity. No difference was found in brain AChE activity. A decrease in erythrocyte mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration in exposed fish suggests a state of anemia. Histological alterations observed in exposed fish included hyperplasia of the interlamellar epithelium, blood congestion in secondary lamellae, and mucous cells hyperplasia and hypertrophy in gills; pycnotic nuclei and hydropic degeneration in liver; testicular damage. These moderate pathological responses in major organs could become crucial during reproduction and under prolonged exposure periods.