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Helping Hawaiian corals recover

New findings may hold some Hawaiian corals back from the brink of death. Stanford researchers and their collaborators discovered that corals have five distinct stages of health – a revelation that challenges long-held scientific understanding and holds the promise of a second chance for reefs on the verge of collapse.

Their findings, published this week in Scientific Reports, could help resource managers and policymakers better understand how to predict and prevent reefs from crossing “tipping points” that can be hard to anticipate and difficult to reverse.

“These breakthrough findings, that corals are much more complex than being simply vibrant or dead, were really only possible because we were able to rely on big data – thousands of surveys from across Hawaiʻi,” said Larry Crowder, the Edward Ricketts Provostial Professor of Marine Ecology and Conservation at Stanford’s Hopkins Marine Station and a senior fellow at the Stanford Woods Institute for the Environment.

The economic value of Hawaiʻi’s coral reefs is estimated at over $10 billion with direct economic benefits, such as fisheries and tourism, of $360 million per year. These reefs are vital to Hawaiʻi’s $800 million annual marine tourism industry through world famous surfing and diving locations. Coral reefs also provide considerable commercial, recreational and subsistence fishing opportunities. However, reefs near urban areas have experienced increased stress from human and land-based activities, in addition to over half of Hawaiʻi’s reefs bleached during recent ocean warming events. There is, therefore, a pressing need to identify reefs near tipping points and to effectively prioritize and manage reefs that are more likely to be resilient to stress. These findings can help.

“It’s like preventing a car from driving off a cliff,” said lead author Mary Donovan, a postdoctoral scholar at UC Santa Barbara and the Hawaiʻi Institute of Marine Biology. “We’re now realizing there are clues that can signal before the car will veer off the road – or corals lose their ability to bounce back from a disturbance – that we can identify before it’s too late.”

 

Categorizing reefs

To uncover complexities around tipping points on coral reefs, the researchers standardized and analyzed over three thousand underwater surveys collected over the past fifteen years – the most thorough study to date.

The team identified five “regimes” for Hawaiian coral reefs: one had low levels of both corals and fish; another had low levels of corals and high levels of fish, and three others varied ecologically but were previously considered as a single phase with high coral. This more nuanced understanding will help inform pathways to solutions to keep coral reefs alive and thriving.

“This study gives scientists, managers and other stakeholders a more sophisticated understanding of coral reef health. It’s now up to us to use these findings to enact meaningful management systems and give corals the best chance for recovery,” said Kendra Karr, Senior Scientist at Environmental Defense Fund’s Oceans Program and paper co-author.

 

Applications for Coral Reef Conservation

This research, conducted in collaboration with government and non-profit partners, will be incorporated into management plans as part of the State’s “30 by 30” target to effectively manage 30 percent of Hawaiʻiʻs nearshore ocean waters by 2030.

There is also promise for broader application to other reefs around the world. The timing is ripe, as 60 percent of the world's reefs are estimated to be destroyed over the next 30 years, and the value of coral reefs globally is $9.9 trillion.

In addition to coral reefs, the findings could also prove useful toward other ecosystems that are complex and threatened from human impacts in the same way as reefs, like rainforests or the African savannas. 

"These findings will allow us to take a big step forward in understanding how corals, which have incredible cultural and economic value, are impacted by both human activities and environmental stressors,” said Lisa Wedding, a research associate at Stanford’s Center for Ocean Solutions. “We can use these findings to inform management approaches for coral reefs and other ecosystems to help pull them back from possible tipping points.”

 

 

Co-authors of the publication include scientists from the University of Hawaiʻi at Mānoa; National Geographic Society; National Oceanic Atmospheric Administration; Stockholm Resilience Center; Royal Swedish Academy of Sciences; Bangor University; Lancaster University; University of California Santa Barbara; Conservation International; Environmental Defense Fund, University of Arizona; Curtin University; and California Polytechnic State University.

 

This research was supported by the Gordon and Betty Moore Foundation, the NOAA Coral Reef Conservation Program, and the Hawaiʻi Division of Aquatic Resources.

 

Photo credits: NOAA PIFSC, L. Kramer, HIHWNMS

 

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Contact Information:

Larry Crowder, Stanford Hopkins Marine Station: (831) 402-6938, larry.crowder@stanford.edu

Nicole Kravec, Stanford Center for Ocean Solutions: (415) 825-0584, nkravec@stanford.edu 

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