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Live corals first mapped before and after the sea heat: winners and losers identified


Low Coral Bleaching in Hawaii, 2015 By Greg Asner, Center for Global Discovery and Conservation Sciences

Research findings can help manage and build an elastic network of coral reefs.

As the temperature of the world’s oceans rises, so will the number of cases of coral discoloration. When corals are bleached, they become more vulnerable to other stressors such as water pollution. However, many reefs are home to corals that thrive despite warming oceans. Elucidating the complex problem of coral bleaching and its impact on their survival or death can be crucial to conserving coral reefs – ecosystems on which more than half a billion people all over the world rely on food, work, leisure and coast protection.

For the first time, researchers have mapped the location of living corals before and after a major sea heat wave. In a new study, scientists show where corals survive despite rising ocean temperatures caused by climate change. The study also found that coastal development and water pollution have a negative impact on coral reefs.

In a study published on May 2, 2022 Proceedings of the National Academy of Sciences Scientists from the University of Arizona from the Laboratory of Global Futures Julie Ann Wrigley show that different corals and the environment affect the likelihood of their survival when the ocean temperature rises. The results also show that advanced remote sensing technologies make it possible to expand reef monitoring like never before.

From their home in Hawaii, ASU researchers from the Center for Global Discovery and Conservation Science took to the skies at the Global Airborne Observatory (GAO). The aircraft is equipped with modern spectrometers that reflect ecosystems both on land and under the ocean surface. With these maps, researchers can assess changes in coastal ecosystems over time.

“Re-mapping corals from GAO ​​showed how the Hawaiian coral reefs responded to the massive bleaching event in 2019,” said Greg Asner, lead author of the study and director of the Center for Global Discovery and ASU Conservation Science. We found coral “winners” and “losers”. And these winning corals are associated with cleaner water and less coastal development, despite the higher water temperatures. ”

When the Hawaiian Islands faced massive bleaching in 2019, GAO mapped live coral cover along eight islands before the wave of sea heat came. Using these data, researchers have identified more than 10 potential coral refuges – habitats that could be a safe haven for corals facing climate change. Among potential shelters, coral mortality was 40% lower than on neighboring reefs, despite similar thermal stress.

The results also showed that reefs near highly developed shores are more prone to mortality during the heat. When development occurs on land, the amount of pollution entering the reef ecosystem increases, creating unfavorable conditions for coral reefs that are already struggling to survive during water warming.

“This study supports Hawaii Holomua Marine 30 × 30 initiative “Not only by identifying areas affected by ocean heat waves, but also by refusion zones,” said Brian Nilsson, co-author of the study and head of the Hawaii Water Division, “these findings could be included in management plans to help build a sustainable network of reef regions. and maintaining the reefs of Hawaii and the communities that depend on them in the future. ”

The Holomua 30 × 30 initiative aims to create maritime control zones in 30% of Hawaii’s coastal waters. Coral reefs in Hawaii are an integral part of island life associated with culture and livelihoods. Understanding which corals have survived is key to achieving focused and effective conservation.

“Previous approaches have failed to provide effective measures that could improve coral survival during the heat or identify heat wave resistance sites known as coral refugees for rapid protection,” said Asner, who is also director of the Global Airborne Observatory. “Our findings underscore the new role that coral mortality and survival monitoring can play for targeted conservation that protects more corals in our changing climate.”

Reference: “Mapped coral mortality and refusion in archipelago-scale marine heat wave” Gregory P. Esner, Nicholas R. Vaughn, Robert E. Martin, Sean A. Foo, Joseph Heckler, Brian J. Nilsson and Jamison M. Gove May 2, 2022, Proceedings of the National Academy of Sciences.
DOI: 10.1073 / pnas.2123331119

The Center for Global Discovery and Conservation Science at ASU collaborated in this study with the Hawaiian Department of Water Resources and the Pacific Ocean Fisheries Research Center of the National Oceanic and Atmospheric Administration. The Pefe Lenfest Ocean Charitable Foundation program supported this study.


The Center for Global Discovery and Conservation Science at the University of Arizona creates innovative scientific discoveries and outcomes that directly benefit the environment, resource management, and policy efforts. The center manages the Atlas of Coral Helen and the Global Airborne Observatory among various projects and laboratories and is based on the ASU campus in Tempe and in Hill, Hawaii.

The center is part of the Laboratory of Global Futures by Julie Ann Wrigley, the world’s first comprehensive institution dedicated to empowering our planet and its inhabitants so that all can prosper. It is built on the deep experience of ASU and the use of an extensive global network of partners for continuous and extensive exchange in all fields of knowledge to address complex social, economic and scientific challenges posed by current and future threats of environmental degradation. ASU, which ranks 1st in the US and 2nd in the World Times Higher Education Impact Rankings and 1st in the Sierra Club Class of Schools in the ranking of the most sustainable universities, allows the Global Futures Laboratory to address important issues related to the future planet Earth.

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