Sunscreen Versus Coral Reefs

“Slip-Slop-Slap” was the iconic sun protection campaign prominent during the 1980s, when the singing, dancing Sid Seagull encouraged people to reduce sun exposure and protect themselves against an increasing risk of skin cancer. There’s no doubt that slopping on loads of sunscreen, together with the use of sun protection clothing, has played a key role in the dramatic shift in sun protection attitudes and behaviour, but at what cost?

You don’t have to be a scientist to understand that anything you spread onto your skin also leaches out into the sea every time you take a swim and studies have shown that 25% of the sunscreen you put on your body spreads into the sea in a mere 20 minutes. Even those labelled “water resistant” will eventually end up in the water and researchers have estimated that between 4,000 and 13,000 tons of sunscreen wash into the world’s coral reef areas each year.

It’s a well-publicised fact that coral reefs are in jeopardy. Half of them have been dying a slow death over the last 30 years or so and on our current course only 10% will still be living by the year 2050.


What is to blame?

The usual suspects are climate change, coastal developments, marine pollution and overfishing. We can do little, if anything, to influence these, but who would have imagined that a substance which protects humans from a terrifying condition, could be playing a small part in the demise of coral reefs. And this is something we can alter.

Corals normally need pristine, clear, warm, relatively nutrient-free water to survive, so anything that alters the delicate balance of their habitat will put their survival into great danger.

A common ingredient found in the majority of sunscreens is toxic to coral and is thought to be a contributing factor to the decline of reefs around the world. Oxybenzone is a UV-filtering chemical compound found in thousands of brands of sunscreen worldwide and this can be fatal to baby coral. A study published by Environmental Contamination and Toxicology, based in Hawaii and the U.S. Virgin Islands, discovered that Oxybenzone deformed corals, encouraging the young coral to encase itself in its own skeleton resulting in bleaching, where they turn white and die. They also found that it damaged the coral’s DNA, neutering their ability to reproduce.

Some ingredients can also awaken dormant viruses in the symbiotic algae called zooxanthellae that live inside reef-building coral species. The chemicals cause the viruses to replicate until their algae hosts explode, spilling viruses into the surrounding seawater, where they can infect neighbouring coral communities. Zooxanthellae provide coral with food energy through photosynthesis and contribute to the organisms’ vibrant colour.

You might think that 4,000 tons of sunscreen, diluted in the oceans of the world would not pose a toxic threat, but according to new research, toxicity occurs at a concentration of 62 parts per million; that’s the equivalent of a drop of water in an Olympic sized swimming pool.

Unfortunately the damage that humans cause to coral reefs seems to be long lasting and may even be permanent. When natural disasters such as hurricanes hit the reefs they have the ability to recover, but the damage caused by humans tend to wear the reefs down to a point where they can no longer bounce back. Even when new reefs are planted they only survive for a few years in a lot of cases and then they die.

Remember that it is not just the coral which is being effected. Researchers have identified nearly 4,000 kinds of fish and tens of thousands of invertebrates that thrive and depend on some 800 types of known coral. The corals support a unique ecosystem which will perish if the coral dies and the creatures that dwell on the reefs will disappear from our oceans.

What can we do?

OK so we can’t influence climate change on our own, nor can we stop coastal developments or overfishing, but we can do something about the type of sunscreen we use. Look carefully at the ingredients of the sunscreen you are about to buy. Avoid any with oxybenzone, octocrylene, 4MBC, butylparaben and octinoxate and go for one which has a physical filter which reflects instead of absorbs ultraviolet radiation. Try to find one marked as “reef friendly”, but you must still beware, as this is not a regulated term and you need to read the label carefully and make your own decision. Be careful how much sunscreen you use and try and avoid sprays, where much of the contents end up on your clothes, on the sand, in the water and in the air. Apply the sunscreen 15 minutes before going into the water to allow your body time to absorb it. The other thing you can do is to invest in some sun-protecting T-shirts or shirts.

So we can all take a small bit of responsibility for the future of our coral reefs when we go out in the sun. Skippers and Charter Brokers can educate their crews and clients on what sun protection to use. As individuals we must get used to reading labels, as we are doing more and more when buying food and drink. And most importantly don’t take the attitude of “whatever I do is not important enough to help”. This is an occasion where we really can make a difference.

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