Photochemical response of the scleractinian coral Stylophora pistillata to some sunscreen ingredients

Ultraviolet (UV) filters and preservatives, which are common constituents of sunscreens and other cosmetics, are reported as a threat for coastal coral reef ecosystems; however, few studies have assessed the effects of these compounds on coral health. This study presents the chronic effects (of measured, long-term and low concentrations) of some preservatives (ethylparaben, butylparaben), mineral UV filter (zinc oxide, ZnO) and organic UV filters (terephthalylidene dicamphor sulfonic acid, drometrizole trisiloxane, ethylhexyltriazone, butylmethoxydibenzoylmethane and 2-ethylhexyl 2-cyano-3,3-diphenylacrylate) on the maximal photosynthetic efficiency ( F v / F m ) of the symbionts associated with the scleractinian coral Stylophora pistillata. It first shows that for many organic filters, measured concentrations were significantly lower than nominal concentrations, due to the lipophilic nature of the compounds. In addition, the F v / F m was more sensitive to ZnO than all other sunscreen ingredients, with exposure to 90 µg L −1 ZnO for 35 d, reducing F v / F m by 38% compared with controls. The other UV filters tested showed no adverse effect on coral symbionts or animal tissue up to the concentration corresponding to their water solubility limit (and even above). Similarly, no adverse effect was observed in our conditions with the preservative ethylparaben, but the preservative butylparaben decreased the F v / F m by 25% at the highest concentration of 100 µg L −1 . None of the sunscreen ingredients were as toxic to corals as the reference pollutants tributyltin, diuron and monuron, which significantly inhibited F v / F m at 10, 1 and 0.1 µg L −1 , respectively. Overall, this study highlights the need to improve our knowledge on the in situ concentrations of UV filters and preservatives as well as their individual and combined effects on corals.