Exposure of zebrafish to environmentally relevant concentrations of mercury during early life stages impairs subsequent reproduction in adults but can be recovered in offspring.

• Early life Hg exposure impairs reproduction in adult zebrafish. • Early life Hg exposure has intergenerational effect on reproduction of F 1 females. • Reproductive damage caused by early life Hg exposure is recovered in F 1 males. • Reproductive damage caused by early life Hg exposure is recovered in F 2 females. Mercury (Hg) is a global pollutant that poses potential threats to health of fishes. Although effects of Hg on reproduction of fishes have been documented, little is known about effects of exposure to Hg2+ during early life stages on subsequent reproductive fitness of adults or whether these effects can be transferred to offspring. In this study, zebrafish embryos were exposed to environmentally relevant concentrations of Hg2+ (0.6, 3 or 15 μg/L) for 5 days and then depurated in clean water for another 115 days. Exposure to Hg2+ during early life stages disturbed the balance of sex hormones and gametogenesis by altering expression of mRNA for genes involved in the hypothalamic-pituitary-gonadal axis, which resulted in delayed gonadal development and lesser gonado-somatic index, thereby resulting in lesser fecundity. A similar, but less pronounced effect was observed in F 1 females that were not exposed directly to Hg, whereas such damage was neither observed in F 1 males nor either sex during the F 2 generation. Exposure to Hg2+ during early life can impair subsequent reproduction in adults and has intergenerational effects on F 1 females, but this reproductive damage can be recovered in F 1 males and in F 2 females. [ABSTRACT FROM AUTHOR]