Effects of chronic exposure to benzophenone and diclofenac on DNA methylation levels and reproductive success in a marine copepod

The UV-filter benzophenone and the anti-inflammatory diclofenac are commonly detected in the environment. The aim of this study was to assess the multigenerational effects of chronic exposure to low concentrations of these chemicals on toxicity and DNA methylation levels in the copepod Gladioferens pectinatus. Acute toxicity tests were conducted to determine the sensitivity of G. pectinatus to the chemicals. All chemicals impacted breeding, hatching and egg viability. Diclofenac (1 mg.L(-1)) reduced the number of eggs per gravid female. Benzophenone (0.5 mg.L(-1)) decreased egg hatching success. Exposure to the reference toxicant copper (0.02 mg.L(-1)) led to unsuccessful hatching. Effects on DNA methylation was estimated by the percentage of 5- methylcytosine. The treatments resulted in strong differences in DNA methylation with increased methylation in the exposed animals. The two chemicals impacted both egg viability and the induction of differential DNA methylation, suggesting potential intra- and trans-generational evolutionary effects.