Hawai‘i Reef Health: Study Finds Two-thirds Of Hawaiian Reefs Are Covered With Algae


Identification of multiple reef states in the Hawaiian Islands can help to better understand and manage impact on critically important corals

​​Honolulu/Arlington, Va. USA – According to a study published today in the Philosophical Transactions of the Royal Society – Biological Sciences, just one-third of the coral reefs ecosystems in Hawai‘i are dominated by healthy corals and calcareous algae. The study, led by the Stockholm Resilience Centre, Stanford University’s Center for Ocean Solutions, the University of Hawaii, NOAA, the Scripps Institute of Oceanography, and Conservation International-Hawai‘i, also identified the key stressors of these reef systems, including declines in herbivorous fish abundance, ocean temperature and pollution run-off from land. ​

“While some algal cover is natural on Hawaiian reefs, it is unexpected to find that turf algae dominate more than half of all reefs we examined,” said Jean-Baptiste Jouffray of the Stockholm Resilience Centre at Stockholm University. “This raises the question whether turf-dominated reefs are stable configurations or transitional states moving towards macroalgae or conversely towards coral recovery.”

Coral reefs are among the most biologically diverse ecosystems on earth, and harbor approximately 25% of all marine species. They also provide a wide range of ecosystem goods and services that are crucial for economic and societal development, such as food, coastal protection and income from tourism. Coral reefs are of critical importance in Hawai‘i, supporting near-shore fisheries. The average resident of Hawai‘i consumes three-times as much seafood – up to 60% of which is imported - than other Americans. Healthy reef ecosystems can help restore the islands’ seafood security. 

Some of the healthiest corals in Hawai‘i are in the remote northwestern Hawaiian Islands, where they are effectively conserved as part of the Papahānaumokuākea Marine National Monument. Identifying the healthy, natural condition of coral reefs is important for managers, seeking to protect the reefs and the ecosystem services they can generate. 

"The condition of coral reefs around Hawaii is determined largely by the abundance of herbivorous fish,” said Magnus Nyström, Associate Professor at the Stockholm Resilience Centre at Stockholm University. “Hence, keeping herbivore populations healthy should be of key concern for safe-guarding Hawaiian coral reefs. However, other human stressors such as land run-off, also seem to be important, especially for the occurrence of turf algae.”

“This study tells us that there are tipping points for coral reefs, where even small increases in human stressors can impart major changes in the status of reefs,” said Jack Kittinger, director of Conservation International-Hawai‘i. “From a management perspective, understanding the safe operating space is critical, and these tipping points give us concrete milestones to shoot for to protect healthy reefs, recover reefs that are in decline, and increase the benefits that reefs provide to communities across our archipelago.”

This week Conservation International is spotlighting the film Coral Reef as part of its provocative environmental awareness campaign, Nature Is Speaking. Voiced by Vampire Diaries star and United Nations Environment Program Goodwill Ambassador Ian Somerhalder, the film reminds humans that coral reefs are the most diverse of all marine ecosystems, the nurseries of the sea, and the critical first line of defense against approaching storms. 
Roughly one-fifth of coral reefs worldwide are already damaged beyond repair. Destructive fishing practices, ocean acidification, and insensitive tourism practices such as snorkelers touching reefs, threaten the long-term conservation of coral ecosystems every day.

Nature Is Speaking is a series of short films voiced by some of the biggest names in Hollywood, including Penélope Cruz, Harrison Ford, Edward Norton, Robert Redford, Julia Roberts, Ian Somerhalder and Kevin Spacey.  "Coral Reef" is available for download on www.natureisspeaking.org. To actively engage in a conversation with Coral Reef, we invite viewers to join the discussion by using #NatureIsSpeaking and the Twitter handle, @CoralReef_CI.

Contact the Authors: 
Phone +33 632 32 67 14 / email Jean-baptiste.jouffray@su.se
Jack Kittinger, Director, Conservation International Hawai‘i​
Phone +1 808 397 9077 / email jkittinger@conservation.org 

For more information, contact:
Kevin Connor, Media Manager, Conservation International 
Office +1 703 341 2405/ email kconnor@conservation.org 

Note to editors:
Conservation International (CI) – Since 1987, Conservation International has been working to improve human well-being through the care of nature. With the guiding principle that nature doesn't need people, but people need nature for food, water, health and livelihoods—CI works with more than 1,000 partners around the world to ensure a healthy, more prosperous planet that supports the well-being of people. Learn more about CI and the "Nature Is Speaking" campaign, and follow CI's work on Facebook, Twitter and YouTube.


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