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Sunscreen is killing coral reefs around the world

Posted on Friday, February 26th, 2010 at 1:20 pm by

A study shows that sunscreen ingredients can awaken dormant viruses in zooxanthellae and cause massive bleaching, then death. As most of us know, Zooxanthellae is the symbiotic algae living inside corals, feeding it through photosynthesis. The chemicals in the sunscreen cause viruses within this algae to rapidly replicate, eventually leading the host algae to explode.

Study leader Roberto Danovaro states that “The algae that live in the coral tissue and feed these animals explode or are just released by the tissue, thus leaving naked the skeleton of the coral.” Researchers estimate that somewhere between 4,000 and 6,000 metric tons of sunscreen washes off swimmers each year, and that up to 10% of the corals reefs around the world are threatened.

Several sunscreen brands where tested by researchers, and all of them contained the four ingredients paraben, cinnamate, benzophenone, and a camphor derivative. Corals were actually shown to bleach within 4 days when exposed to low levels of sunscreen. However, some have claimed that this study does not replicate nature effectively. Robert van Woesik, of the Florida Institute of Technology, points out that plastic bags were used in this study, preventing the dilution of the chemical that would occur in nature. In response, Danovaro says that the negative effects of sunscreen on corals are not dose-dependent, and that the effect is more like “on-off”, so that “Once the viral epidemic is started, it is not a problem of toxicity.”

So, what do we do? We can’t stop wearing sunscreen. Donavaro should choose sunscreens which reflect, instead of absorv, UV radiation. Additionally, he recommends using eco-friendly chemical sunscreen. Interestingly, a group of Australian researchers are developing a sunscreen that employs a natural UV-blocking compound found in corals.

source National Geographic

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