These 3D maps of coral reefs may help us save them

There’s plenty of research about coral reefs bleaching and dying because of warming ocean waters — but one group of researchers is more interested in knowing how corals live and grow. To do that, they’re creating 3D visualizations of coral reefs around the world.

One of these coral reefs is at Palmyra Atoll, an island south of Hawaii. Every year, scientists go back to the island armed with underwater cameras and scuba diving gear. They take thousands of photos of the corals, covering an area of more than 17,000 square feet. In the lab, the photos are then stitched together to create 3D maps that allow researchers to revisit the reef in the comfort of their offices, time traveling from year to year to observe how corals change.

Northern Marianas Islands, May 2014Photo by Stephani Gordon
A scuba diver takes photos for the 3D visualizations at the Northern Marianas Islands, in May 2014.

“When you put the headset on and you’re in one of these 3D models, it’s literally better than scuba diving,” says Clinton Edwards, a graduate student at Scripps. You don’t have to worry about the oxygen tank, the ocean currents, or getting sunburnt, he says. Computer software can also quickly scan the 3D maps and identify all the different coral species.

Edwards and other researchers analyzed one of these photomosaics of Palmyra Atoll and recently published their findings: the corals in this reef tend to cluster together, especially those that are more fragile, they found. That’s because when strong waves come and break the corals apart, the leftover bits and pieces can attach themselves to the rock and keep growing. That allows the corals to weather storms and survive, says study co-author Stuart Sandin, a professor of marine ecology at Scripps.

 Video: Scripps Institution of Oceanography at UC San Diego
Custom software can identify and tag corals of different species in the 3D maps.

Understanding how corals are distributed within a reef — why certain corals are grouped together and some aren’t — is key to protecting coral reefs. The same information on land can help people manage forests: thanks to photographs taken by airplanes and satellites, scientists have been studying individual trees in forests for years, Sandin says. Understanding where trees live and grow, and how far apart from each other they are, for instance, helps forestry managers keep forests healthy. But reefs are obviously underwater, so the same type of information is basically non-existent.

Sandin hopes that creating the 3D photomosaics can help change that. The Palmyra Atoll is part of the 100 Island Challenge, a group of researchers around the world who are taking photos and creating 3D visualizations of reefs on 100 islands, from Palau to Antigua. By comparing the same reefs year to year, and comparing reefs to each other, the researchers hope to better understand how corals are structured, where and how they grow, how they die — and what makes them resilient to environmental changes. This information is key if we want to save coral reefs from dying. If we want to replant reefs, for instance, we have to know how the reefs are organized.

 Video: Scripps Institution of Oceanography at UC San Diego
A time series shows how the corals change over several years.

This first paper, published in Coral Reefs, is starting to answer some of these questions. Next, the researchers want to compare data from 2012 to 2016 in order to get a better understanding of how individual corals changed through time, including how they reacted to the worldwide 2015-2016 massive bleaching event.

Sandin says he hopes that the visualizations will become available through VR headsets, similarly to what NOAA is doing, so that people can virtually swim through the reefs. In the meantime, you can watch the 3D maps on YouTube. “It’s a tool to democratize access to coral reefs,” Sand says. “It’s an ability to share coral reefs to allow people to travel different places and learn from different places.”