LIVING COLOR: Healthy corals (left) display vibrant colors. Bleached corals (right) have lost their color.

GARY BELL/OCEANWIDEIMAGES.COM (LEFT), XL CATLIN SEAVIEW SURVEY (RIGHT)

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NGSS: Core Idea: PS1.A   

CCSS: Literacy in Science: 7   

TEKS: 6.2B, 7.2B, 8.2B, 8.11C

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Coral Killer

Governments move to protect reefs from chemicals found in some sunscreens

April 22, 2019
By Jennifer Barone

ESSENTIAL QUESTION:  What types of pollution harm oceans? What actions can people take to tackle these problems?

Last spring, passengers on Hawaiian Airlines received something in addition to their in-flight snacks: sunscreen. Attendants passed out samples to encourage tourists visiting the islands to use types of sunscreen that are safer for corals. Scientists have found that chemicals in some sunscreens currently on the market harm reefs, and the airline hoped to inform people about the problem. Now Hawaii has joined several seaside spots around the world in banning sunscreens that contain these ingredients.

Last spring, passengers on Hawaiian Airlines got something besides their in-flight snacks. Attendants passed out samples of sunscreen. They wanted visitors to the islands to use types of sunscreen that are safer for corals. Scientists have found a problem with some sunscreens on the market. Chemicals in them harm reefs, and the airline hoped to let people know. Several seaside spots around the world have banned sunscreens that contain these chemicals. Now Hawaii has joined them.

REEF MYSTERY

Craig Downs, an environmental toxicologist based at a lab in Virginia, has gathered compelling evidence of the risks that sunscreens pose to reefs. Downs studies how chemicals affect the environment.

A few years ago, he began investigating dying reefs in the Virgin Islands. A local man overheard him and his colleagues discussing the declining reefs and suggested they investigate sunscreen. Beaches in the Virgin Islands receive several thousand visitors a day. Every evening, after tourists returned to their cruise ships, locals saw a slick of washed-off sunscreen on the ocean’s surface.

Craig Downs is an environmental toxicologist at a lab in Virginia. He studies how chemicals affect the environment. He’s found powerful evidence of the risks that sunscreens pose to reefs.

A few years ago, he began studying dying reefs in the Virgin Islands. He and his team were talking about the damaged reefs. A local man overheard them. The man suggested they look at sunscreen. Beaches in the Virgin Islands get several thousand visitors a day. Every evening, the visitors returned to their cruise ships. That’s when locals would see a slick of washed-off sunscreen on the ocean’s surface.

TIERNEYMJ/SHUTTERSTOCK.COM

POLLUTED WATER: An estimated 14,000 tons of sunscreen ends up in the world’s oceans every year.

When Downs’s team tested the seawater, they found high concentrations of a sunscreen ingredient called oxybenzone. They exposed immature coral larvae in their lab to the compound (see Coral Life Cycle). After just a few hours, the baby corals became deformed. Their bodies changed shape. Their mouths developed abnormally. And they started sealing themselves in a hard skeleton too soon, causing them to die. Oxybenzone also made the young corals bleach, or lose the tiny plantlike organisms called algae that supply them with nutrients. “It was horrific,” says Downs.

Downs’s team tested the seawater. They found high levels of a sunscreen chemical called oxybenzone. They exposed young coral larvae to the compound in their lab (see Coral Life Cycle). After just a few hours, the baby corals became deformed. Their bodies changed shape. Their mouths didn’t develop right. And they started sealing themselves in a hard skeleton too soon. That caused them to die. Oxybenzone also made the young corals bleach, or lose their algae. These tiny plantlike organisms provide corals with nutrients. “It was horrific,” says Downs.

CORAL LIFE CYCLE

Corals are made up of tiny tentacled animals called polyps. They grow and reproduce to build reefs. But stress from things like pollution can put these creatures at risk.

Corals are made up of tiny tentacled animals called polyps. They grow and reproduce to build reefs. But stress from things like pollution can put these creatures at risk.

KATE FRANCIS

Article Image    BABY CORAL: Corals release eggs and sperm into the water. When a sperm meets an egg, a coral larva forms. The larva attaches to the seafloor and grows into a coral polyp.

Article Image    BABY CORAL: Corals release eggs and sperm into the water. When a sperm meets an egg, a coral larva forms. The larva attaches to the seafloor and grows into a coral polyp.

KATE FRANCIS

Article Image    GROWING UP: The polyp builds a hard, cup-shaped skeleton under itself. As the coral grows, it adds material to its home.

Article Image    GROWING UP: The polyp builds a hard, cup-shaped skeleton under itself. As the coral grows, it adds material to its home.

KATE FRANCIS

Article Image    TINY BUILDERS: Young corals build homes on top of other corals to create reefs—a process that can take up to 10,000 years. Each polyp gets most of its energy from algae called zooxanthellae living within its tissues.

Article Image    TINY BUILDERS: Young corals build homes on top of other corals to create reefs—a process that can take up to 10,000 years. Each polyp gets most of its energy from algae called zooxanthellae living within its tissues.

KATE FRANCIS

Article Image    STRESSED OUT: Stress from things like pollution can cause coral to lose their algae. Their skeletons turn white as a result, a process known as bleaching. If the stress continues long term, the corals can die.

Article Image    STRESSED OUT: Stress from things like pollution can cause coral to lose their algae. Their skeletons turn white as a result, a process known as bleaching. If the stress continues long term, the corals can die.

CORAL LIFE CYCLE

Corals are made up of tiny tentacled animals called polyps. They grow and reproduce to build reefs. But stress from things like pollution can put these creatures at risk.

Corals are made up of tiny tentacled animals called polyps. They grow and reproduce to build reefs. But stress from things like pollution can put these creatures at risk.

KATE FRANCIS

Article Image    BABY CORAL: Corals release eggs and sperm into the water. When a sperm meets an egg, a coral larva forms. The larva attaches to the seafloor and grows into a coral polyp.

Article Image    BABY CORAL: Corals release eggs and sperm into the water. When a sperm meets an egg, a coral larva forms. The larva attaches to the seafloor and grows into a coral polyp.

KATE FRANCIS

Article Image    GROWING UP: The polyp builds a hard, cup-shaped skeleton under itself. As the coral grows, it adds material to its home.

Article Image    GROWING UP: The polyp builds a hard, cup-shaped skeleton under itself. As the coral grows, it adds material to its home.

KATE FRANCIS

Article Image    TINY BUILDERS: Young corals build homes on top of other corals to create reefs—a process that can take up to 10,000 years. Each polyp gets most of its energy from algae called zooxanthellae living within its tissues.

Article Image    TINY BUILDERS: Young corals build homes on top of other corals to create reefs—a process that can take up to 10,000 years. Each polyp gets most of its energy from algae called zooxanthellae living within its tissues.

KATE FRANCIS

Article Image    STRESSED OUT: Stress from things like pollution can cause coral to lose their algae. Their skeletons turn white as a result, a process known as bleaching. If the stress continues long term, the corals can die.

Article Image    STRESSED OUT: Stress from things like pollution can cause coral to lose their algae. Their skeletons turn white as a result, a process known as bleaching. If the stress continues long term, the corals can die.

SAVING CORALS

Downs’s findings made headlines. Many local, state, and national governments began taking action. Last year, Hawaii, the Pacific nation of Palau, and the Caribbean island of Bonaire all passed laws banning sunscreens containing oxybenzone and octinoxate, another chemical that damages corals. Hawaii’s ban will go into effect in 2021, as will a similar law that passed this year in the city of Key West, Florida.

Beachgoers don’t have to risk getting burned to protect corals, though. They can cover up by wearing sun-protective clothing. To protect any skin that remains exposed, people can choose sunscreens that contain reflective minerals, like zinc oxide and titanium dioxide. They’re a safer option for aquatic ecosystems. “When we reduce the stress from sunscreen pollution,” says Downs, “we can help corals have a chance to recover.”

Downs’s findings made headlines. Many local, state, and national governments began taking action. Hawaii, the Pacific nation of Palau, and the Caribbean island of Bonaire all passed laws last year. They banned sunscreens with oxybenzone and octinoxate. That’s another chemical that damages corals. Hawaii’s ban will go into effect in 2021. So will a similar law that passed this year in the city of Key West, Florida.

But beachgoers can protect corals without getting burned. They can cover up with sun-protective clothing. There’s also a way to protect exposed skin: Choose sunscreens that contain reflective minerals, like zinc oxide and titanium dioxide. They’re safer for water ecosystems. “When we reduce the stress from sunscreen pollution,” says Downs, “we can help corals have a chance to recover.” 

CORE QUESTION:  What evidence did scientists collect that demonstrated the danger certain sunscreen chemicals pose to corals?

Chemistry
Atoms, Compounds & Ions
Earth Science
Earth's Waters
Biology
Human-Animal Interaction

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