Tourist sunscreen ‘killing off coral reefs’
Ingredients in many sunscreen brands cause rapid and complete bleaching of corals, say scientists.
Tourists who wear sunscreens may be contributing to the death of the Great Barrier Reef and other coral reefs around the world, new research has revealed.
Scientists in Italy believe that up to 10 per cent of coral reefs are threatened by bleaching caused by chemicals in widely-used creams that are sold to protect users from the sun’s damaging UV rays.
Between 4,000 and 6,000 tonnes of sunscreen wash off swimmers annually in oceans worldwide, mostly in warm tropical climates where reefs are popular tourist attractions. But scientists at Marche Polytechnic University in Ancona found that many brands of sunscreen contain ingredients that can stimulate viruses in the algae, known as zooxanthellae, which live within corals. Zooxanthellae play an essential role in providing the vibrant colour associated with corals by supplying food energy through photosynthesis.
The chemicals found in sunscreens — paraben, cinnamate, benzophenone, and a camphor derivative — cause the viruses to replicate until their algae hosts explode, spilling viruses into the surrounding seawater, where they can infect neighbouring coral communities. Without the algae, the coral turns white and dies.
The study looked at the effect of sunscreen on corals in the Pacific, Atlantic and Indian oceans and the Red Sea. The research, which was funded by the European Union, indicated that the protection people need in order to enjoy coral reefs while wearing skimpy clothing is damaging precisely what draws tourists to reefs. In the case of the Great Barrier Reef — which attracts 1.6m people each year — this could jeopardise an industry that the Australian Ministry of Tourism calculates is worth some £2.31bn.
“Sunscreens cause the rapid and complete bleaching of hard corals, even at very low concentrations,” said Roberto Danovaro, who led the research team.
"By promoting viral infection, sunscreens can potentially play an important role in coral bleaching in areas prone to high levels of recreational use by humans.”
The study is the latest to highlight the extent to which tourism is damaging coral reefs. According to the Worldwide Fund for Nature, a quarter of the world’s coral reefs is at imminent risk of collapse through human pressures; a further quarter is under a longer-term threat of collapse.
Climate change is compounding the problem. In recent years, increased sea surface temperatures have caused coral bleaching, in which the plant-like organisms that make up coral die and leave behind the white limestone skeleton.
Australian scientists are considering plans to cover sections of the Great Barrier Reef with giant canopies to try to reduce the destruction of the habitat by bleaching. A two-year trial that ended in 2006 used large shade cloths tethered to pontoons, and provided results described as “encouraging”.