Coral bleaching

Environmental chemistry

Physics

Astronomy

Coral

Sunlight

Radiochemistry

Chemistry

Ecology

In vitro

Phototoxicity

Anemone

Anthozoa

Zooxanthellae

Sea anemone

Ultraviolet radiation

Symbiosis

Bacteria

Genetics

Biochemistry

Botany

Biology

Science

The reported toxicity of oxybenzone-based sunscreens to corals has raised concerns about the impacts of ecotourist-shed sunscreens on corals already weakened by global stressors. However, oxybenzone's toxicity mechanism(s) are not understood, hampering development of safer sunscreens. We found that oxybenzone caused high mortality of a sea anemone under simulated sunlight including ultraviolet (UV) radiation (290 to 370 nanometers). Although oxybenzone itself protected against UV-induced photo-oxidation, both the anemone and a mushroom coral formed oxybenzone-glucoside conjugates that were strong photo-oxidants. Algal symbionts sequestered these conjugates, and mortality correlated with conjugate concentrations in animal cytoplasm. Higher mortality in anemones that lacked symbionts suggests an enhanced risk from oxybenzone to corals bleached by rising temperatures. Because many commercial sunscreens contain structurally related chemicals, understanding metabolite phototoxicity should facilitate the development of coral-safe products.

Conversion of oxybenzone sunscreen to phototoxic glucoside conjugates by sea anemones and corals