Comparative toxicities of four benzophenone ultraviolet filters to two life stages of two coral species.

The benzophenone (BP) organic ultraviolet (UV) filters have been measured in seawater at ng/L to µg/L levels, but more data on their effects in non-target marine organisms are needed. Corals can be exposed to BPs due to wastewater discharges and coastal recreational activities. In this study, toxicities and bioaccumulation of BP-1 (2,4-dihydroxybenzophenone), BP-3 (oxybenzone), BP-4 (sulisobenzone) and BP-8 (dioxybenzone) to larvae and adults of two coral species, Pocillopora damicornis and Seriatopora caliendrum, were assessed at concentrations ranging from 0.1-1000 µg/L. BP-1 and BP-8 exposure caused significant settlement failure, bleaching and mortality of S. caliendrum larvae [lowest observed effect concentration (LOEC): ≥10 µg/L] compared to the other BPs, while none of the tested compounds and concentrations affected P. damicornis larvae. Nubbins were more sensitive to BP-3, BP-1 and BP-8 than larvae. Overall, BP-1 and BP-8 were more toxic to the two tested species than BP-3 and BP-4, which matches the relative bioaccumulation potential of the four BPs (BP-8 > BP-1 ≈ BP-3 > BP-4). A conservative risk assessment using the effect concentrations derived from this study showed that BP-3, BP-1 and BP-8 pose high or medium risk to the health of corals in popular recreational areas of Taiwan and Hong Kong. Our study suggests that future ecotoxicological studies of corals should take their sensitivities, life stages and metabolic capacities into consideration.