Coral’s double sided relationship with sunscreen

Coral reefs are well known for their beauty, yet their double-sided relationship with sunscreen is little known. Coral requires sunlight for life; however, the future existence of these coral landscapes is also threatened by it. Due to its presence in the photic zone in the ocean (the depth of the ocean where light is able to penetrate the water), coral requires protection from the sun’s UV rays. However, contamination of reefs by chemicals used in human sunscreen has toxic effects on the animal.

Coral takes part in a symbiotic partnership with photosynthetic algae – the algae create food for the coral via photosynthesis, in return for nutrients. Therefore, the coral must reside in the photic zone of the ocean, so that the algae are able to photosynthesise. Consequently, coral need sun protection. The mystery, however, is: how does coral provide this protection? The solution to this mystery has come from scientists working at King’s College London (KCL). A three year project involved taking samples from the Great Barrier Reef in Australia. Genetic and biochemical changes to the coral were observed, when the coral is exposed to light at high water temperatures. The study has revealed that algae within the coral produce a compound, which is transported to the coral, where it is modified into a sunscreen. The exact compound is unknown, but is suspected to be involved in a biochemical pathway called the shikimate pathway – which is only seen in plants, fungi and algae. If the compound can be identified and reproduced, this has huge potential applications for human use.

KCL are very close to reproducing this compound, and if all goes well, expect to test it within the next two years. This also means that a pill that offers UV (ultra violet) protection in the skin and eyes may be available to buy within the next five years. It has been said that the pill would only be available on prescription, to prevent overdoses and harm to people’s health. However, it should be noted that a certain amount of sunlight is necessary for the production of vitamin D. Vitamin D is essential for the absorption of calcium in humans, and a deficit can cause a condition known as rickets. KCL have stated that coral may make more than 20 sun protection compounds, but only the structure of a single compound is being researched. This compound will provide a scaffold for a laboratory to make a synthetic version. Extensive tests will need to be carried out, such as skin tests and toxicology reports, before the pill is confirmed as ready and safe to use.

Ironically, this application may save the future of coral reefs, due to adverse effects of current sunscreens on coral reef communities. A chemical in some sunscreens is toxic to coral at very low concentrations – 62 parts per trillion (this is equivalent to one drop of water in an Olympic swimming pool). The chemical, oxybenzone, has toxic effects on young coral – causing hormonal disruption and DNA damage, which ultimately leads to the death of the coral. The presence of oxybenzone also increases the likelihood of coral bleaching. This is when coral reject the algae they are in a symbiotic relationship with, and lose their colour. It is the algae within the coral that gives the reefs their bright and beautiful colours. Bleaching has been increasingly prevalent in recent years due to rising sea temperatures.

Due to tourism, between 4000 and 6000 tons of sunscreen enter coral reefs around the world each year. Therefore, the use of sunscreen containing oxybenzone has the potential to cause catastrophic effects on the coral reefs of the world. It should be noted that this research is not advocating people to stop using sunscreen, but instead highlights the need for ethical consumerism. Sunscreens containing zinc oxide and titanium oxide have been found to have few harmful effects on coral reefs. Tourists are also encouraged to cover the upper half of their torso with more clothing, limiting the amount of sunscreen entering the water. Coral reefs are incredibly important for maintaining ecosystems, and are extremely diverse. As well as being carbon sinks, coral reefs have the highest biodiversity of any marine ecosystem. It is therefore important that we preserve these beautiful natural wonders.


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