Skip to main content

ASU center announces first-ever global coral reef maps

Dr. Alexandra Ordonez collects georeferenced reef data with GPS overhead. Credit: Chris Roelfsema

Alexandra Ordonez collects georeferenced reef data with GPS overhead. Photo by Chris Roelfsema

September 09, 2021

When people think of Arizona State University and the Sun Devils, desert landscapes and simmering Phoenix days come to mind. But for one ASU research team, their setting is tropical islands and beaches — Hawaii to be exact. 

The Center for Global Discovery and Conservation Science — located in Tempe, Arizona, and in Hilo, Hawaii — does not call this paradise home just for the views. This team is leading the way in groundbreaking research to inform climate and biodiversity action around the world. And one of its projects, the Allen Coral Atlas, continues to reach new heights for what is possible. 

On Sept. 8, the Allen Coral Atlas met a major milestone by completing global habitat maps of the world’s tropical, shallow coral reefs. A combination of satellite imagery, advanced analytics and global collaboration has resulted in maps that show the marine ecosystems' benthic and geomorphic data in unprecedented detail. With eyes in the sky, the technology recognizes geomorphic, or seascape structures, up to about 15 meters (52 feet) underwater and benthic data, or the composition of the ocean floor, up to about 10 meters (33 feet) underwater. 

The Allen Coral Atlas is a collaborative project led by the Center for Global Discovery and Conservation Science in partnership with Vulcan Inc., Planet Labs Inc., the University of Queensland (UQ) and the National Geographic Society. Drawing on satellite imagery, the Allen Coral Atlas maps and monitors the world's coral reefs. And with this newest accomplishment, conservation users will have a resource for globally comparable coral reef data, at a scale never before available.

“We now have the highly detailed maps needed to create new spatial plans and marine protected areas,” said Wen Wen, a marine spatial analyst in Indonesia. “The Allen Coral Atlas is playing a large role in prioritizing 30 million hectares of a new MPA (marine protected area) and providing alternative locations for a coastal economic development project of a shoreline airport. This tool is a blessing to our country.”

A marine protected area is an area of the ocean set aside for economic resources, biodiversity conservation and species protection. Basically, it limits human activity to support the reef and ocean ecosystem, and, in effect, the nearby communities that rely on these reefs.

Innovation and collaboration are key to crafting the maps

Before becoming a game-changing conservation tool, the journey of a habitat map begins as satellite imagery from Planet Labs. ASU calculates the water depth, and these calculations are sent with the imagery to the Remote Sensing Research Center at UQ, where scientists use machine learning and analysis to craft the habitat maps. 

Machine learning uses algorithms to classify the pixels in an image into different reef classifications. Just like any student, these algorithms need to learn how to recognize the different pixels. Local teams have contributed more than 450 datasets that “train” the algorithms to do just that. 

After classifying the reefs, these datasets are used to assess the reef maps and check that the classifications are accurate. While turbidity — think sand or sediment in the water — and atmospheric conditions, such as clouds, create barriers when mapping coral reefs, the Allen Coral Atlas leverages collaboration by engaging with teams for feedback and organizing expeditions for additional reef data.

After the regions have been validated and a local expert provides feedback, the habitat maps are sent to the software engineering team at ASU, where they are transformed into visual and downloadable data available to anyone with internet access. Check them out at the Allen Coral Atlas website.

Informing action

With these maps, organizations have a new tool to guide their conservation efforts. 

“It is a gratifying milestone after years of dedicated nonstop teamwork to bring this global map to fruition, but the true value of the work will come when coral conservationists are able to better protect coral reefs based on the high-resolution maps and monitoring system,” said Greg Asner, managing director of the Allen Coral Atlas at ASU. “We must double down and use this tool as we work to save coral reefs from the impacts of our climate crisis and other threats.”

Already, officials from 14 countries are engaged with Allen Coral Atlas team members, working on 48 new marine planning projects using the atlas maps as their foundational data set. 

Vatu Molisa, Vanuatu Project liaison officer for the IUCN Marine Program, explained how the Allen Coral Atlas will be used to inform the region’s efforts to protect coral.

“We will be utilizing this very valuable and important dataset to contribute to our continuing National Marine Spatial Plan and efforts, and look forward to future and continuing collaborations," Molisa said.

The use of the habitat maps goes beyond marine spatial planning, with organizations using the Allen Coral Atlas for disaster recovery, proposed policies for fishing regulations, and the identification and documentation of local threats to coral reef habitats.

Combined with recent innovation — a monitoring system capable of detecting coral bleaching in biweekly increments — the Allen Coral Atlas is now the most complete, consistent, accurate and continually updated resource for coral scientists, policymakers and regional planners. 

In addition to the Allen Coral Atlas, the Center for Global Discovery and Conservation Science team’s research continues to awe the conservation community — from groundbreaking studies, including Shawna Foo’s recently published study on coral and algae relationships, to the first high-resolution mapping of live corals on the Hawaiian Islands, to educational coral videos shot under the waves.

More Science and technology


Two teenagers hug and smile at each other.

ASU study: Support from romantic partners protects against negative relationship stress in teens

Adolescents regularly deal with high levels of stress, which can increase the risk of substance use and experiencing mental…

May 22, 2024
A large bluish-white planet in space.

ASU scientists help resolve 'missing methane' problem of giant exoplanet

In the quest to understand the enigmatic nature of a warm gas-giant exoplanet, Arizona State University researchers have played a…

May 20, 2024
Digital rendering of cells.

Study finds widespread ‘cell cannibalism,’ related phenomena across tree of life

In a new review paper, Carlo Maley and Arizona State University colleagues describe cell-in-cell phenomena in which one cell…

May 20, 2024