Brave New Coral

Human activity has wreaked havoc on coral reefs around the world. Now, under the threat of climate change, coral’s best chance for survival may be human creativity.

- Ashtyn Douglas

Misaki Takabayashi, a marine scientist at the University of Hawaii at Hilo, first noticed nearby reefs were changing in 2014. She was body boarding with a friend one day at Wai’uli, a punchy reef break on the east side of the Big Island, when she caught a glimpse of something white beneath the surface of the water.

“I started paddling for a wave, and when the water sucked up off the reef, I could see fluorescent white coral colonies below me,” recalls Takabayashi. “They looked like ghosts popping out through the water.”

After studying reef ecosystems in Hawaii for over 20 years, Takabayashi knew this wasn’t a good sign. Corals are usually pigmented. Some take on shades of brown. Others are more vibrant, stained with bright blue, green, or red hues, like the ones on the front of travel brochures selling all-inclusive packages to Fijian resorts.

“If these corals were healthy, they would’ve been brown,” says Takabayashi. “Before that day, most surfers probably didn’t even notice the live corals below them because they would’ve blended in with the ocean floor.”

But the bone-white corals she saw that day were far from healthy. They were “bleached,” meaning they’d lost the microscopic symbiotic algae that live inside the corals’ transparent tissue. These über-small organisms, called zooxanthellae, enliven corals with their russet-brown pigmentation and also serve as the corals’ main source of nutrition, using photosynthesis to convert sunlight into energy. Think of them like indispensable solar panels: without them, coral reefs starve and have no energy to grow. If zooxanthellae leave their hosts’ tissue, once-thriving colonies of coral instantaneously become clumps of haunting specters.