Induced Developmental Toxicity Studies With Mercuric Chloride and Polychlorinated Biphenyls on Danio Rerio (Zebrafish) Embryo

Abstract

Introduction: Fish population is generally considered very sensitive to all kinds of environmental changes to which it is exposed, as they are exclusively aquatic with an external mode of fertilization. The aim of this study is to highlight the effects of some of the most powerful environmental toxicants such as mercuric chloride (HgCl2) and polychlorinated biphenyls (PCBs), which alter the behavioral response, embryo survival rate, embryo hatching ratio, mortality rate, and heart rates of Danio rerio (zebrafish) embryo during its developmental stages. Materials and Methods: Zebrafish (D. rerio) were exposed to progressive concentrations of HgCl2 and PCBs. The water quality parameters were analyzed, and the acute toxicity test was conducted using eight fish for different concentrations; the results were compared with the control group. In addition, behavioral changes at each concentration were observed for the individual fish. Results and Discussion: The fish were exposed to various concentrations of 5, 10, 20, 30, 40, 50, and 60 μg/L of HgCl2 and PCB for a period of up to 2 weeks. The toxicity was concentration as well as time dependent. Toxicity tests revealed that the larvae of zebrafish were more sensitive to these toxicants as compared to the embryos.