Residual effects of 3,4-dichloroaniline on offspring born to Ceriodaphnia cf. dubia exposed for multiple generations

One of the acknowledged limitations of conventional toxicity tests is their inability to evaluate the impact of toxicants on subsequent generations. Given their relatively short lifespan, cladocerans in the field may be exposed to toxicants for several generations. However, it is unclear what effect such an exposure regime could have on the cladoceran fitness after removal of the toxicant. This paper aimed to determine the offspring fitness of juveniles produced by adult Ceriodaphnia cf. dubia exposed to residual levels of 3,4-dichloroaniline over four generations. Mass cultures of Ceriodaphnia cf. dubia were maintained for several generations in various concentrations of 3,4-dichoroaniline (0, 2.5, 5, 10, 15 and 20 μg/L). The mass cultures were re-established every generation using 4th brood neonates <24 h old. Each generation, 4th brood neonates <24 h old were also transferred individually into toxicant-free water and examined until the production of their 3rd brood. F1 offspring of mothers exposed to 15 and 20 μg/L 3,4-dichloroaniline showed significantly (p < 0.05) reduced reproduction compared to the controls. No significant (p > 0.05) changes in reproduction due to 3,4-dichloroaniline were observed for the F2 and F3 offspring. However, F4 offspring of mothers exposed to all 3,4-dichloroaniline concentrations showed significantly (p < 0.05) increased reproduction compared to the controls. Possible explanations for the varying influence of maternal 3,4-dichloroaniline exposure on the reproductive output of the offspring are discussed.