Effect of Oxadiazon Herbicide on Physiological,Biochemical and DNA Damage in Common carp (Cyprinus carpio)

Abstract

This study conducted to evaluate the toxic effects of a widely used oxadiazon herbicide,on common carp (Cyprinus carpio) fingerling (15 g). The 96-h LC50 was determined, and the growth performance, serum biochemical and hematological parameters, DNA damage of erythrocytes cells, as well as histopathological changes were also determined in fish exposed to sublethal concentrations (1, 1.5 and 2 ppm) of the herbicide for 30 days. The 96-h LC50 to C. carpio was found to be 3.9 ppm. Weight gain (WG), specific growth rate (SGR) and condition factor (CF) were decreased, while food conversion ratio (FCR) increased in the exposed fish groups (P<0.05). Exposure to oxadiazon significantly increased serum ALT(Alanine transaminase), AST(Aspartate transaminase), ALP(Alkaline phosphatase), and glucose levels, while total protein, cholesterol, and albumin were significantly decreased in the exposed fish groups depend on oxadiazon concentrations and exposure time (P< 0.05). Erythrocytes cells of fish exposed to 1, 1.5 and 2 ppm of oxadiazon showed DNA damage (21.3%, 22.9%, and 28.4%, respectively) , significantly higher than control group (P< 0.05). Moreover, exposure to oxadiazon significantly decreased WBC, RBC, Hb, Hct as well as serum albumin, glucose, and total protein levels, while serum ALP was significantly increased in the exposed fish groups (𝑃�< 0.05). No significant differences were found in MCV, MCHC and MCH levels between oxadiazon treatments and control groups (P> 0.05). Oxadiazon was also induced marked histological changes included hyperemia, hyperplasia of lamellar epi-thelium, inflammatory cell infiltration, aneurysm, rod-like structures of secondary gill lamellae in the gills; fat changes in the hepatocytes, fibrosis, focal inflammatory cells and fibrocyte aggregation, diffuse and focal necrosis, hyperemia and hemorrhage and bile duct hyperplasia in the liver; hyperemia, necrosis of tubular epithelium and proteinuria in the kidney; myofibril change, necrosis, and inflammatory cell infiltration in the muscles. Changes in size and number of melanomacrophage centers were also observed in the kidney, spleen, and liver tissues of exposed fish. This study indicated that oxadiazon is highly toxic to common carp and exposure to this herbicide lead to adverse effects on the fish.