Oxybenzone (Benzophenone-3) Induces Antioxidant Responses and DNA Strand Breakage in Aiptasia pallida, a Coral Research Model Organism

The toxicity of oxybenzone (benzophenone-3; BP-3), a UV filter present in coral reef waters at toxic concentrations, has been incompletely characterized for oxidative stress responses in adult cnidarians. In order to examine this, Aiptasia pallida (an anemone commonly used as a coral research model) was exposed to oxybenzone at concentrations of 0.02, 0.2, 2.0, and 3.0 mg/L for 5, 10, and 30 days (n = 4 tanks per treatment). Catalase (CAT) and superoxide dismutase (SOD) activity, glutathione levels, and the alkaline comet assay (% DNA in tail) were analyzed. CAT increased significantly at all concentrations and timepoints, with 80.6% maximum induction at 2.0 mg/L on Day 30 and a LOEC of 0.02 mg/L. SOD showed no significant response at any timepoint. The levels of glutathione increased at Day 5 for the two highest concentrations, but decreased at Day 10 for 3.0 mg/L. Genotoxic effects were significant at Days 5 and 10, with a threshold between 0.02 and 2.0 mg/L. A significant positive correlation between group mean CAT activity and % DNA in the tail contrasted with a null SOD–DNA association, identifying hydrogen peroxide, not superoxide, as the proximate genotoxic driver in adult cnidarian tissue. These results indicate that oxybenzone induces oxidative stress responses in A. pallida.