Coral Reefs & Sunscreen

A Background of Coral Reefs

Coral reefs are the most biodiverse marine ecosystems on Earth and provide humans with billions of dollars worth of ecosystem services. Benefits of these reefs include fisheries, tourism, coastal protection from waves and floods, new medicines, recreation opportunities, and carbon dioxide removal from the atmosphere to name a few[1]. The National Oceanic and Atmospheric Administration claims that coral reefs are vital to marine ecosystems as 25% of the ocean’s fish depend on them for food and shelter[2].

Unfortunately, coral reefs are under threat from bleaching events. Coral bleaching occurs when coral is stressed due to changes in its surrounding environment such as increased ocean temperatures and ocean acidification (as a result of climate change). If this stress continues, the coral will eventually die. Bleaching occurs when symbiotic algae living in the coral leave the coral’s tissues due to changes in the environment created by external threats.

When the algae are gone, so are the coral’s food source and radiant colors. When coral reefs begin to die, the rest of the ecosystem is in danger because they are the base of the food chain. For example, dinoflagellates are one of the dominant microorganisms that live in the coral and give it vital nutrients to grow, as well as allow other marine species to flourish. Therefore, when the symbiotic relationship between dinoflagellates and coral is jeopardized by threats like bleaching events, then other organisms that live on higher trophic levels (the position a species occupies in the food web) are in danger. When primary producers (e.g., coral) begin to perish, a trophic cascade may occur where an increased mortality rate of dependent marine species on coral may become threatened, endangered, or even go extinct. Fortunately, corals are able to recover from bleaching events, but only if surrounding conditions improve before they die.

The Dangers of Sunscreen

Most of Sun Bum’s sunscreens are not truly reef safe such as these

Coral bleaching stems from anthropogenic causes such as pollution and rising ocean temperatures; however, many sunscreens are catalysts as well. It is estimated that up to 14,000 tons of toxic sunscreen enter the ocean every year[3]! The common UV blocking chemicals found in popular sunscreens responsible for coral bleaching are oxybenzone and octinoxate[4]. Hawaii, among other places, have banned such chemicals due to the fact that they damage the DNA of coral and decrease their defense against bleaching. Areas in the Caribbean that lack these regulations and are frequently visited by tourists have seen a sharp increase in bleaching events, while less popular destinations in the area have healthy coral reefs. This is an example of “swimmer pollution”, a trend that arises when sunscreen worn by a group of highly concentrated swimmers gets washed off into the ocean.

Sunscreen’s toxic chemicals can also damage coral in more indirect ways. Ingredients like oxybenzone are readily absorbed through the skin and can be detected in urine within 30 minutes of application[5]. When the toilet is flushed or sunscreen’s toxic chemicals are washed off down the shower drain, such chemicals that are still present are sent to water treatment facilities or in rural communities, the watershed. A process known as bioaccumulation can occur, where these chemicals can build up in organisms if they are absorbed more quickly than excreted, and eventually move up the food chain eaten by large mammals such as humans.

Moving Forward

Reef safe sunscreen available at Bird Rock Surf Shop in La Jolla, CA

It is advised to use mineral based sunscreens such as zinc oxide or titanium dioxide which still protect human skin from the sun as well as coral from bleaching events[6]. In addition, make sure to check the label on your sunscreen to avoid other toxic ingredients such as oxybenzone, octinoxate, octocrylene, PABA, homosalate, parabens, 4-methylbenzylidene, triclosan, any form of microplastic, and nanoparticles or nano-sized zinc[7].

Educating people about reef friendly sunscreen and encouraging them to use eco-friendly alternatives can serve as a quick, effective, and affordable way to do your part. Your individual efforts and consumption choices matter; ultimately, you can make a difference!

A Background of Coral Reefs

The Dangers of Sunscreen

Moving Forward

Reef Friendly Brands to Use