Are Coral Reefs Signaling the End of the World?

Bleached corals in the Maldives. Credit:  Hannah Prewitt

Bleached corals in the Maldives. Credit: Hannah Prewitt

Some 50% of the world’s reefs are gone. Can the rest be Saved?

A 500-mile stretch of the earth’s largest and most biodiverse living structure, the Great Barrier Reef, was wiped out during the record-setting high temperatures of 2016. This resilient ecosystem has stood up to centuries of regular temperature fluctuations, but reached a tipping point when the warm El Niño currents of that year were intensified by virtually unprecedented atmospheric warming. This mass reef mortality event is part of a broader trend due to the phenomenon known as bleaching, which has caused the loss of an estimated fifty percent of reefs globally.

Source: National Oceanic and Atmospheric Administration

Source: National Oceanic and Atmospheric Administration

The effects of climate change and pollution are made starkly apparent in coral reef ecosystems, the delicately-balanced rainforests of the sea. Thousands of species are intricately connected through these structures; in fact, it’s estimated that reefs support up to twenty-five percent of marine life. Reefs are essential for coastal communities, providing food, livelihood, and protection, not to mention important social, cultural, and recreational activities – and billions in tourism revenue. This resource is threatened everywhere by toxic chemicals, warming temperatures, agricultural runoff, marine plastic, and other system-altering pollutants, all of which have intensified rapidly over the last few decades.

The loss of reefs is devastating to those who understand the necessity and breathtaking beauty of healthy reef systems. Communities are taking action to protect what’s left. Aside from stopping climate change, there are many ways to slow the effects of bleaching before it’s too late, including focusing on more direct anthropogenic impacts. That’s why the Kahaulelio family of Waialua, which is on the North Shore of Oahu, was involved in helping to pass an influential bill in Hawaii banning toxic sunscreens, an enormous victory for conservation in their community.  

We’ll come back to the inspiring story behind the sunscreen legislation, but first, let’s take a detour to explore the phenomenon of bleaching.

What is bleaching?

To understand bleaching, it’s necessary to take a closer look at coral anatomy. Reefs are uniquely part animal, part plant, and part mineral. They consist of tens of thousands of tiny organisms called polyps, which collectively build their exoskeleton structures from calcium carbonate extracted from the surrounding water. These polyps use miniscule tentacles to collect zooxanthellae, the single-celled organisms that live symbiotically inside polyps and produce energy via photosynthesis.

Corals thrive in warm waters, but because they live at the upper limit of their thermal tolerance, they are sensitive to changing conditions. If the temperature becomes too extreme, the zooxanthellae reach a light and temperature maxima at which they can no longer perform photosynthesis. At this saturation point, the zooxanthellae are expelled from the polyp hosts and energy production ceases. As the polyps die, there is a loss of pigmentation (the cause of the “bleaching” effect) and the reef structures, which are partially composed of living tissue, decay.

The bleaching process can also be set off by exposure to chemicals, such as oxybenzone and octinoxate, rather than heat. These harmful chemicals, which are disturbingly abundant in the ocean, pollute the surrounding water, organisms, and algaes such that corals cannot sustain their usual functions.

Corals fluorescing. Credit: The Ocean Agency / xl catlin seaview survey

Corals fluorescing. Credit: The Ocean Agency / xl catlin seaview survey

In the final stages of the bleaching process, corals often produce stunning fluorescent pigments that absorb damaging light wavelengths in a last-ditch attempt at self-preservation. Depressed coral observers in the Netflix documentary Chasing Corals couldn’t help interpreting this brilliant display of colors as a heart-wrenching final plea for protection. (Watch this documentary if you’re prepared to have an existential cry about corals.)

When bleaching occurs, entire classes of organisms are threatened. Many animals residing in reef ecosystems thrive on complex symbiotic relationships, creating fascinating and extensive chains of interdependency. Many animals that do not depend on live coral, such as sea turtles and sharks, are nonetheless dependent on the topographic complexity provided by healthy coral growth. The breakdown of reefs is a death sentence for vast swaths ocean life, and it’s only a matter of time before this leads to dire consequences for humankind.

Lizard Island on Australia's Great Barrier Reef, 2016. Credit: The Ocean Agency/xl catlin seaview survey

Lizard Island on Australia's Great Barrier Reef, 2016. Credit: The Ocean Agency/xl catlin seaview survey

Hawaii Takes Action

Nohea Kahaulelio, a surfer from Waialua on the North Shore of Oahu, was taking a Toxicology course at Pitzer College when she dove into research about coral bleaching and the effects of chemical sunscreen products. This issue hits close to home for her. “My ohana and I have spent most of our lives in the ocean, swimming, surfing, and snorkeling. We have barbecues almost every weekend at our homebreak, Ali’i Beach, where we learned to surf. The ocean here in Hawaii is not only my playground, but also that of kids all around the island and those who come to visit.”

As Hawaii’s reefs began to degrade, Nohea and her family took notice. “The amount of damage to developing corals and other marine organisms is drastic,” she said. “It’s very important to help keep the reefs healthy in Hawaii and all over the world. It’s an ecosystem that so many marine organisms depend on for shelter and for food. I think of reefs as the strong base of the ocean; they help create waves, protect smaller fish from bigger fish, and act as the mother home for the a variety of marine offspring to grow up in.” For residents whose lives revolve around the ocean, the stress that pollution created on their local marine environments was becoming apparent.

Both Nohea and her twin sister are set to graduate in May with degrees in Environmental Analysis. Their mother, Iris Kahaulelio, is a science teacher at Kahuku High School specializing in biology, medical biotechnology, and forensics. As the twins worked on their toxicology policy recommendation project in their California college class, the whole family began exploring coral reef bleaching. Even their younger brother undertook a sixth-grade science project exploring the adverse effects of chemicals commonly found in sunscreen on coral algaes. Inspired by her children’s passion, Iris began working with Dr. Craig Downs of Haereticus Environmental Laboratory, who conducts water quality testing and built momentum for legislative solutions.

Iris compiled this mounting research and shared it with Hawaii’s state representatives and senators. The letter detailed the team’s findings: “Peer reviewed, scientific research has been conducted and published worldwide indicating that the chemicals Oxybenzone and Octinoxate are toxic to coral and threaten overall coral reef health by causing coral bleaching, and harming or killing coral larvae by inducing gross deformities and DNA damage. These toxic chemicals act as endocrine disruptors in coral, preventing their restoration in damaged areas and reducing their resiliency to climate change. And when it is gone, it will be gone forever.” She went further to explain the alarming bioaccumulation of Oxybenzone in marine food chains, which can lead to a variety of diseases among humans, and emphasized that this contamination is widespread with some 500 tons of sunscreen polluting Hawaiian waters. “I consider myself a steward of our beautiful 'aina,” she wrote, “and it is our kuleana to protect and preserve this paradise we are all so fortunate to call home.”

This letter was part of a massive community effort leading to the introduction SB 2571, the bill that would ban the sale and use of all sunscreen containing oxybenzone and oxicotinate. “It is our playground to protect,” Nohea said, “so with support from non-profit conservation programs and awareness of community members here in Hawaii, we were able to grab the attention from members of our government – especially Governor Ige, who has already done many things to help protect Hawaii’s beautiful land and ocean ecosystems.” Governor Ige signed the bill into law on July third, 2018.

The Kahaulelios with Governor Ige on the day of the bill’s signing.

The Kahaulelios with Governor Ige on the day of the bill’s signing.

Waves of Resistance

How exactly does a group of scientists pass an unprecedented bill contrary to the interests of multi-billion dollar companies like Johnson & Johnson? “A scientist friend described it as being similar to a military campaign operating on 23 fronts – seriously,” said Iris. “What was crucial was very, very solid science, and communicating that science so everyday folks could see how it impacted their own lives. I was on an email thread that included international scientists, and being in a time of international political unrest, it was heartwarming to see people coming together to support the effort.” They were met with forceful resistance from certain politicians and lobbyists, but ultimately the best interests of the community won.

Nohea hopes this story of successful civic engagement will inspire other concerned citizens to take action in their communities. “Sharing knowledge and information by word of mouth helps spark change in your community, and lays the groundwork for something bigger and better for future generations,” she said. As an instructor of a family run North Shore surf school, Aloha Surfing Ohana, Nohea has found a platform to promote healthy and reef-safe sunscreens: “We’ve shared our mana’o (knowledge) of chemical sunscreens’ harsh effects with our visitors for many months now.” In addition to education, pressuring elected officials is a critical pathway to change. “Making members of your government aware by sending letters and emails, or making phone calls, is a way to show that you care for your environment – and that they need to know that.”

The only long-term solution for protecting what’s left of the world’s corals is slowing climate change. This will require international cooperation in treaties such as the Paris Climate Agreement that aim to reduce emissions quickly and substantially. Currently, prospects for meeting emissions targets are looking bleak; a recent UN report found that the atmosphere is likely to warm a lethal 2.7 degrees Fahrenheit by the year 2040. But, as the Kahaulelio family has demonstrated, global collective action can begin at the grassroots level. We all depend on healthy oceans – so call your representatives and senators; vote; educate; and ditch those toxic chemical sunscreens!

Sea Maven extends a warm thank you to Nohea, Iris, and the Kauhaulelio family for sharing their findings and participating in interviews. Their bill will have far-reaching positive implications. Lexie Varga and Lucy Hartman contributed research on the correlation between climate change and bleaching.