Findings could help manage and build a resilient network of coral reefs


As the world sees ocean temperatures rise, it will also see more cases of coral bleaching. When corals bleach, they become more vulnerable to other stressors such as water pollution. However, many reefs are home to corals that persist despite warming oceans. Unraveling the complex issue of coral bleaching and its impact on coral survival or death can be critical to the conservation of coral reefs – ecosystems on which more than half a billion people around the world depend for food, work, entertain and protect the coastline.

For the first time, scientists have mapped the location of living corals before and after a major marine heat wave. In the new study, research shows where corals are surviving despite rising ocean temperatures caused by climate change. The study also reveals that coastal development and water pollution negatively affect coral reefs.

In the study, published today in Proceedings of the National Academy of Sciences, Scientists from Arizona State University’s Julie Ann Wrigley Global Futures Laboratory reveal that different corals and environments influence the likelihood of their survival as ocean temperatures rise. The results also demonstrate that advanced remote sensing technologies offer an opportunity to intensify reef monitoring like never before.

From its home in the Hawaiian Islands, ASU researchers from the Center for Global Discovery and Conservation Science flew to the Global Airborne Observatory (GAO). The aircraft is equipped with advanced spectrometers that map ecosystems both on land and below the ocean surface. With these maps, researchers can assess changes in coastal ecosystems over time.

“Repeated coral mapping with the GAO revealed how Hawaii’s coral reefs responded to the massive bleaching event of 2019,” said Greg Asner, lead study author and director of the ASU Center for Discovery. world and conservation science. “We found coral ‘winners’ and ‘losers’. And these winning corals are associated with cleaner water and less coastal development despite high water temperatures.”

When the Hawaiian Islands faced a massive bleaching event in 2019, the GAO mapped live coral cover along eight islands before the marine heat wave arrived. With this data, the researchers identified more than 10 potential coral refuges – habitats that could provide a safe haven for corals facing climate change. Among the potential refuges, there was up to 40% less coral mortality than on neighboring reefs, despite similar thermal stress.

The results also indicated that reefs close to heavily developed coastlines are more likely to die during heat waves. When development occurs on land, the amount of pollution entering the reef ecosystem increases, creating an unfavorable environment for coral reefs that are already struggling to survive warming water.

“This study supports Hawaii’s Holomua Marine 30×30 initiative by identifying not only areas impacted by ocean heat waves, but also areas of refuge,” said Brian Neilson, study co-author and chief of Hawaii Aquatic Resources Division. “These findings can be incorporated into management plans to help build a resilient network of reef regions and support Hawaii’s reefs and the communities that depend on them into the future.”

The Holomua 30×30 initiative aims to establish marine management areas on 30% of Hawaii’s coastal waters. Coral reefs in Hawaii are an integral part of life on the islands, tied to culture and livelihoods. Understanding which corals survive is key to achieving targeted and effective conservation.

“Previous approaches have failed to provide concrete interventions that can improve coral survival during heat waves or locate hotspots of heat wave resistance, known as coral refuges, for protection. fast,” said Asner, who is also director of the Airborne Global Observatory. “Our findings highlight the new role that monitoring coral mortality and survival can play for targeted conservation that protects more corals in our changing climate.”

ASU’s Center for Global Discovery and Conservation Science collaborated on this study with the Hawaii Division of Aquatic Resources and the National Oceanic and Atmospheric Administration’s Pacific Islands Fisheries Science Center. The Pew Charitable Trusts Lenfest Ocean program supported this study.

Source of the story:

Material provided by Arizona State University. Original written by Makenna Flynn. Note: Content may be edited for style and length.

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