Adding insult to injury: Effects of chronic oxybenzone exposure and elevated temperature on two reef-building corals

We studied the effect of chronic oxybenzone exposure and elevated temperature on coral health. Microcolonies of Stylophora pistillata and Acropora tenuis were cultured in 20 flow-through aquaria, of which 10 were exposed to oxybenzone at a field-relevant concentration of ~0.06 μg L −1 at 26 °C. After two weeks, half of the corals experienced a heat wave culminating at 33 °C. All S. pistillata colonies survived the heat wave, although heat reduced growth and zooxanthellae density, irrespective of oxybenzone. A. tenuis survival was reduced to 0% at 32 °C, and oxybenzone accelerated mortality. Oxybenzone and heat significantly reduced photosynthetic yield in both species, causing a 5% and 22−33% decrease, respectively. In addition, combined oxybenzone and temperature stress altered the abundance of five bacterial families in the microbiome of S. pistillata . Our results suggest that oxybenzone adds insult to injury by further weakening corals in the face of global warming. Highlights ➢ Chronic effect study on corals combining oxybenzone and elevated temperature ➢ Oxybenzone affected photosystem II of coral photosymbionts and altered coral microbiome ➢ Temperature effects were stronger than oxybenzone effects ➢ Sensitivities were species-dependent ➢ Oxybenzone adds insult to injury by weakening corals in the face of global warming