Effects of Acute Toxicity of Chlorpyrifos (EC 50%) and Associated Histological Alterations in Gills, Liver and Kidney of Mozambique Tilapia, Oreochromis mossambicus (Peters, 1852)

Abstract

Background: The pesticides are known to adversely affect the quality of water and create hazards for aquatic life that results in severe damage to non-target freshwater organisms including fish. Among them, the organophosphorus pesticide, chlorpyrifos (CPF) is one of the most commonly used pesticides for controlling various kinds of pests in agriculture. Pesticides after entering in to the body of fish bring about histopathological and biochemical changes in different target and non-target organs. Hence, the present study aimed to investigate the toxicity effects of Chlorpyrifos (CPF) and associated histopathological changes in the gill, liver and kidney of the Mozambique Tilapia, Oreochromis mossambicus under the acute toxicity concentrations. Methods: Static bioassay was carried out for Chlorpyrifos with Oreochromis mossambicus as test animal for a period of 96 hrs as per standard methods and LC50 values were calculated through Probit analysis. The fishes were exposed to five acute concentrations (0.033, 0.066, 0.132, 0.264 and 0.528 ppb). The gill, liver and kidney tissues were collected from the fishes exposed to the pesticide and standard histology protocol was followed to investigate the histopathological changes. Result: The histological changes observed in the gill included lamellar aneurysm, curling of secondary lamellae, shortening of the secondary lamellae, hypertrophy of epithelial cell, fusion of secondary lamellae, deformation of the cartilage core, blood congestion, collapsed secondary lamellae, excessive mucus secretion, disorganization of the secondary lamellae, haemorrhage at primary lamellae, necrosis, haemorrhage at secondary lamellae. The most common histopathological changes in the liver were characterized by cellular necrosis, degeneration of hepatocytes, nuclear degeneration, fat deposition, rupture of nucleus, hypertrophied hepatocytes, blood congestion, blood sinusoids, cellular hypertrophy, increased pycnotic nucleus, cirrhosis and hemosiderosis. Further, histological changes like appearance of dilated lumen, hypertrophied epithelial cells, severe haemorrhage, blood congestion, melanomacrophage aggregation, narrowing of lumen, degenerated tubule, degenerated glomerulus, shrunken glomerulus and distended glomerulus were observed in the kidney. Thus, it is evident from the present study that Chlorpyrifos can be a potential toxicant affecting the fishes at tissue level on dose and time dependent manner which are expected to affect the other physiological processes in the long run.