Abstract
The purpose of this study was to investigate the toxicity and the distribution of mercury (Hg) in the main tissues of freshwater fish (Oreochromis niloticus) after being exposed to water containing Hg(II). A sample group of 10 fish, of mean weight 80–100 g wet weight, were exposed to different concentrations of Hg (0.0012; 0.0049; 0.0141; 0.0524; 0.1126; and 0.5110 mg-HgII/L) for 72 h under controlled conditions using the static method in ponds. A control medium was also prepared in two replications. Mortality of fish was closely monitored, and the test was repeated three times. For the toxicity test, observations were based on behavior, mortality, and anatomical pathology. The methodology was based on the OECD guidelines for testing of chemicals and lethal concentration (LC50) and particularly using the probit method. Thus, the mean value was obtained from two replications and then further calculated by a software (MiniTab® 16 version). Prior to analysis, samples were first lyophilized. The total concentration of Hg accumulation in the fish organs was analyzed using heat-vaporization atomic absorption spectrometry (HV-AAS) and a MA2000 automatic mercury analyzer. Results showed that toxicity (LC50) of freshwater fish was 0.1435 mg-Hg(II)/L. The internal organs showed some pathological changes including pale gills, anemic eyes, and a whitish body color after the exposure. Furthermore, histopathologically, exposure to mercury might also affect other organs, such as gills, liver, and hepatopancreas. Mercury was found in trace amounts, and its accumulation was found to be at least in the gills. Meanwhile, the highest accumulation was found in the muscle tissue with approximately 5.7183 µg/g dry weight. If they are put in order, the mercury accumulation in the tissue organs was varied from the highest to lowest one: Muscle > eye > bone > head > gill. Finally, it can be concluded that the Hg exposure could affect the histopathological condition of the tested fish.
Highlights
Due to its toxicity, mercury became an international public concern, and it occurs in various forms and bioaccumulates in food webs where it can exert toxic impacts on the organism itself and its Toxics 2019, 7, 58; doi:10.3390/toxics7040058 www.mdpi.com/journal/toxicsToxics 2019, 7, 58 prey
In some settings, inorganic mercury can be in high concentrations and there is a need to know about the toxicity of inorganic mercury to local environments and fish species
The purpose of this work is to understand the acute toxicity (LC50 -72h) and chronic histopathological effects of Hg(II) on the freshwater fish Oreochromis niloticus after they were exposed to water contaminated with Hg(II)
Summary
Mercury became an international public concern, and it occurs in various forms and bioaccumulates in food webs where it can exert toxic impacts on the organism itself and its Toxics 2019, 7, 58; doi:10.3390/toxics7040058 www.mdpi.com/journal/toxicsToxics 2019, 7, 58 prey. Mercury became an international public concern, and it occurs in various forms and bioaccumulates in food webs where it can exert toxic impacts on the organism itself and its Toxics 2019, 7, 58; doi:10.3390/toxics7040058 www.mdpi.com/journal/toxics. In some settings, inorganic mercury can be in high concentrations (e.g., some mines including gold artisan mines) and there is a need to know about the toxicity of inorganic mercury to local environments and fish species. The main purposes of this experiment were to reveal the acute toxicity and chronic histopathological effects of Hg(II) on the local fish Oreochromis niloticus. After exposure to Hg(II), the pathological changes that occurred included pale gills, anemic eyes, and a whitish body color. Our findings confirm that histopathologically, internal organs of gills, liver, and hepatopancreas were greatly affected due to
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
