Effect of sub lethal concentrations of cadmium and lead on Oreochromis niloticus

فرضية

Effect of sub lethal concentrations of cadmium and lead on Oreochromis niloticus
Abstract
The aim of this study was to evaluate the effect of heavy metal on Oreochromis niloticus was exposed to different concentrations of cadmium chloride and lead acetate for 96 h. The effects of sub-lethal exposure on haematological parameters, liver functions, and kidney functions were also investigated in O. niloticus. There were significant decrease of cadmium or lead exposure on erythrocyte count, haemoglobin concentration, and haematocrit values. There were significant effects on other haematological parameters (MCV, MCH, and MCHC). Cadmium or lead exposures were time and dose increased the creatinine, uric acid levels, alanine transaminase (ALT) and aspartate transaminase (AST) activities. The present investigation indicates that the cadmium chloride and lead acetate are toxic to aquatic organisms. Keywords: Cadmium chloride, Lead acetate, Haematological parameters, Liver function, Kidney function. Accepted on December 07, 2016 Introduction Heavy metal contamination is one of the greatest vital ecological complications today. Heavy metals may enter into aquatic ecosystems and induce stress symptoms in fish. Some metals are essential since they play an important role in biological systems, while some others are nonessential metals as they have no known role in biological systems [1]. Toxic metal contaminants in aquatic water are disposed to increase gradually thereby representative the greatest risk to human consumers of fish and other seafood. Inquiries on the toxic effect of metals upon fish are attended by the analysis of variations in some biochemical and haematological parameters in fish [2,3]. Cadmium (Cd) is reflected one of the greatest toxic contaminants present in polluted water and may cause kidney, liver and skeletal injuries [4,5]. Whereas, lead (Pb) is a toxic pollutant and continuous exposure to Pb even at low concentrations has been established as a risk factor causing hepatotoxicity, nephrotoxicity, and reproductive and behavioral dysfunctions [6]. In fish, even at sublethal meditations of Cd and Pb have a sensitive biochemical effect, causes serious physiological harmful effects [7]. Toxicity studies applying fish under controlled environments provide, through the evaluation of mortality, reproductive success, behavioral, damage to tissues, hematological changes, and important information corresponding to the effects of pollutants on the biota of a natural aquatic ecosystem [8]. Tilapia (Oreochromis sp.) is one of the most important freshwater used in the estimation of the quality of marine systems [9,10]. Serum enzymes such as alkaline phosphatase (ALP), alanine transaminase (ALT) and aspartate transaminase (AST) are important serum markers to study the health of animal species [1]. The present study was aimed to evaluate the effect of Cd and Pb at different concentrations on some haematological and biochemical parameters of Oreochromis niloticus.