Drone snaps detailed images of 300-year-old coral

A shoebox-sized flying robot outfitted with cameras can film coral reefs from up to 200 feet in the air, which allows scientists to conduct precise species population surveys over large areas and assess the impact of climate change.

Like undiscovered groves of giant redwoods, centuries-old living corals remain unmapped and unmeasured. Scientists still know relatively little about the world’s biggest corals, where they are, and how long they have lived.

The robot in question is a four-rotor, remote-controlled drone developed by Ved Chirayath, an aeronautics graduate student at Stanford University.

Chirayath teamed up with Stanford Woods Institute Senior Fellow Stephen Palumbi to pioneer the use of drone technology to precisely map, measure, and study shallow-water reefs off Ofu Island in American Samoa.

“Until now the challenges have been too high for flying platforms like planes, balloons, and kites,” Palumbi says. “Now send in the drones.”

Chirayath, who also works as a scientist at NASA’s Ames Research Center, analyzed the drone’s footage using software that removes distortions caused by surface wave movements and enhances resolution.

To link the drone aerial footage to close-up images of corals, the researchers are photographing reefs from below the water using a 360-degree camera.

The result is a centimeter-scale optical aerial map and panoramic photographs of coral heads that stitch together thousands of images into one.


Time may be running short

Researchers say the window of time to study these mysterious ecosystems, which provide sustenance and livelihoods to a billion people, may be closing.

Pollution, destructive fishing practices, and climate change impacts such as warmer, more acidic ocean water threaten corals and their role as habitat for about a quarter of all ocean species.





Using the ripples





“The lensing takes a huge problem in looking through the surface of the water and turns it into an advantage,” Palumbi says. “It not only removes the ripples but uses their magnification to enhance the image.”

Some of Ofu’s corals, protected by the National Park Service, are 15-20 feet across and 300 years old or more. They live in the “Village of Elders,” an expanse of back-reef lagoon that seems to be a perfect incubator for long-lived corals.

Time machines

Palumbi initially plans to use drone-generated maps to measure the location and size—an age indicator—of corals in the Ofu reefs. Then, he will use the drone-captured images to model current flow and water exchange rates in Ofu’s lagoons to better understand climate change’s effects on coral.

By overlaying a water temperature map on a census of the oldest corals, he hopes to gain insights into the conditions that sustain this kind of longevity.

“These corals are time machines that were living before European culture discovered the Samoan islands,” Palumbi says. “What do they have to tell us about that long-ago time? What do they tell us about the likely future?”

Source: Stanford University