NASA Is Getting the “Before” Picture of the World’s Threatened Reefs

The CORAL mission, launching this month, is getting the big picture view of the Pacific’s coral reefs. 

Published June 2, 2016

Dressed in a linen shirt, shorts, and flip-flops, oceanographer Eric Hochberg greets me in his small office at the Bermuda Institute of Ocean Sciences in St. George’s, Bermuda—a cutting-edge marine laboratory that retains the atmosphere of an Edwardian field station.

Hochberg, though, is anything but casual when he talks about his work: the future of the world’s coral reefs.

Hochberg is the leader of NASA’s new Coral Reef Airborne Laboratory (CORAL) project—the largest aerial survey of coral reefs to date. The three-year project, beginning this month, will give scientists, advocates, and policymakers a detailed look at the conditions in major marine ecosystems in the Pacific Ocean.

To date, most reef research has been conducted with a scuba tank and tape measure; a method that Hochberg says offers only a limited perspective. “It’s like walking in the woods for an hour,” he says, referring to the capacity of a scuba tank, “and trying to understand the entire forest based on a few trees.”

“We need this big picture,” he adds. “We’re talking about global change, and we need to get a handle on it.”

To this end, the CORAL team will use NASA’s Portable Remote Imaging Spectrometer (PRISM) to survey Hawai‘i, Palau, the Mariana Islands, and sections of Australia’s Great Barrier Reef. Mounted in a Gulfstream jet flying at 8,500 meters, the detector will scan the amount of light that is reflected off the ocean’s underwater surfaces and translate the wavelengths into a map-like graphic, called an image cube, for scientists to analyze. Divers will collect in-water measurements to verify PRISM’s findings.

Post-flight, researchers will identify the ratios of coral, sand, and algae in the images—robust reefs have more coral, dying reefs have more algae—and correlate them with local temperatures, wave action, biodiversity, and water chemistry. They’ll also look at the reefs’ primary production and the corals’ ability to grow their structures. The results should offer clues to how these factors shape the ecosystems.

Importantly, having such a broad survey will give scientists baseline data against which future observations can be compared, and a way to assess how these reefs are changing because of pollution, sedimentation, fishing, and climate change.

“Coral reefs are the quintessential canary in the coal mine,” says NASA’s Michelle Gierach, CORAL’s lead scientist. “They’re the first ecosystem to respond to the local impacts of climate change. We don’t know enough about them.”

CORAL’s data may also help address some enduring questions, such as how reef ecosystems react to different environmental and anthropogenic stressors; how much healthy coral a reef needs to thrive; and how reefs bounce back from injury, including bleaching.

Though much of the public discussion around coral bleaching has likened the issue to a slow apocalypse, Elizabeth McLeod, a climate scientist with the Nature Conservancy, says there is reason for hope. Scientists are discovering that some corals are more resilient than others. In 1998, warmer water temperatures driven by El Niño killed up to 90 percent of the coral in reefs around Palau. But five years later, “there was phenomenal recovery,” McLeod says.

“If corals are left alone, they can recover after warming. But in some cases, we’re not giving them time to recover,” she says.

It’s too soon to tell if the Great Barrier Reef and others will prove similarly resilient, says Anne Cohen, a marine biologist at Woods Hole Oceanographic Institution. Finding, understanding, and protecting resilient reefs are now top scientific priorities. If CORAL is successful, it will “provide critical information about just what is happening on reefs that we can’t often get to,” Cohen says.

Hochberg, CORAL’s leader, is just eager to get started. “What are we going to see when we look at the whole reef? I think it will be transformative.”