Mercury Accumulation and Elimination in Different Tissues of Zebrafish (Danio rerio) Exposed to a Mercury-Supplemented Diet

Hugo C Vieira,Andreia C M Rodrigues,Fernando Morgado,Sizenando Abreu,Amadeu M V M Soares

doi:10.3390/jmse9080882

Hugo C Vieira, Andreia C M Rodrigues + Show 3 more

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https://doi.org/10.3390/jmse9080882

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Abstract

In this study, we evaluated the bioaccumulation of mercury in zebrafish (Danio rerio) exposed to mercury-contaminated food for 21 days and the depuration of mercury for a subsequent post-exposure period of 28 days. Four tissues (muscle, liver, gills, and skin) were analyzed for mercury content. Overall, data indicated that Hg accumulation in the liver is faster than in other tissues. Furthermore, the liver is the tissue with the highest accumulation rate per day (0.021 µg Hg g−1 day−1), followed by muscle, skin, and gills. Conversely, the Hg depuration rates in different tissues showed the following order: gills > skin > muscle > liver. The bioaccumulation factor values of liver and muscle increased linearly during the uptake period. The ratios between mercury concentration in liver and muscle during the experiment also increased during the uptake period and remained higher than 1 during the elimination period, suggesting that Danio rerio needed more than 4 weeks of depuration. Finally, the distribution of Hg in the water column during the accumulation period is Hg particulate > Hg dissolved, and during the depuration period it is the opposite, mercury particulate < mercury dissolved. In conclusion, this study contributes to a better understanding of the differences in Hg dynamics during the accumulation and depuration stages in a model fish, also emphasizing the alterations on Hg available in the water column.

Highlights

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Adult zebrafish Danio rerio were obtained from the zebrafish facility established at the Biology Department of the University of Aveiro (Portugal)
Danio rerio individuals used in this study (Figure 1) shows thatsignificant the organismsdifferences were well adapted to the experimental conditions, as no (p adapted to the experimental conditions, as no significant differences (p > 0.05) in condition index (CI) during the trial period were observed

Summary

Introduction

Mercury (Hg) is one of the most toxic elements found in the environment due to its persistence, bioaccumulation, and lack of biological functions [1,2]. In addition to these characteristics, Hg has been recognized as deleterious to human and ecosystem health even at low concentrations [3]. This trace element occurs naturally in the environment as a result of natural processes of emission, including erosion of mineral deposits, volcanic emissions and forest fires. Hg concentrations have greatly increased in the last decades due to anthropogenic activities such as the discharge of industrial effluents, wastes from mining activities, and combustion of fuels [4,5]

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