Effects of three sunscreens on the ecophysiology of hard and soft corals from the Maldives.

Local pollution with cosmetic products, particularly from tourism-related activities, can threaten coral reefs. The potential negative effects of sunscreens on corals caused several countries to ban certain sunscreens or ingredients. Many companies advertise their sunscreens as "reef-safe" or "coral-friendly", but scientific analysis is necessary to verify these claims. This study compared three sunscreens, V.Sun™ (Sun Protection Factor (SPF) 50), Surface™ (SPF 50), and ARUUN™ (SPF 30), through tank experiments conducted in the Maldives. The short-term (96 h) response of the hard corals Acropora digitifera, Pocillopora verrucosa, Porites lobata, and the soft coral Sarcophyton sp. to sunscreen exposure (230 mg L) was assessed. Tissue loss only occurred for A. digitifera and P. verrucosa with Surface™ (4-16 %) and ARUUN™ (96 %, both species) sunscreens. ARUUN™ sunscreen also caused severe pigmentation loss for all species, while V.Sun™, Surface™, and control-treated corals, showed only mild or no pigmentation loss. Overall, A. digitifera and P. verrucosa were more sensitive to sunscreen exposure than P. lobata and Sarcophyton sp. Despite all sunscreens labelled "reef-safe" or "coral-friendly", ARUUN™ sunscreen, containing the mineral UV filter zinc oxide (ZnO), showed severely negative effects. Surface™, but particularly V.Sun™, both with chemical UV filters, caused mild or no effects on the investigated corals. This study highlights major differences between sunscreens indicated "reef-safe" or "coral-friendly", and advocates for standardised evaluation of protection labels for cosmetic products.