Scientists report new findings on the role that fish play in balancing coral, algae on reefs - Arizona State University
When people think of coral reefs, images of beautiful colors and structures come to mind. But beyond aesthetic pleasure, coral reefs provide numerous benefits, ranging from food security and coastline protection to their role in coastal traditions and cultures. Although reefs cover less than 1% of the ocean floor, they support about 25% of marine life and earn their nickname: the rainforests of the sea.
A major challenge to reefs today is whether corals can persist under changing climate. One way that climate affects corals is by stimulating the overgrowth of algae that can smother the reef, making life tough for new corals to survive. 
Herbivore fish, such as yellow tang, help to prevent algae from overgrowing coral on reefs. Photo by Shawna Foo Download Full Image
To better understand the balance between coral and algae, scientists at Arizona State University's Center for Global Discovery and Conservation Science explored the role of herbivorous fish in keeping check on one of the main antagonists in coral-algae fight for reef space, known as "turf algae." Their findings were published on Aug. 9 in Coral Reefs, the Journal of the International Coral Reef Society.
Led by postdoctoral researcher Shawna Foo, the team utilized 1,476 fish and benthic surveys from 2010 to 2019 across the eight main Hawaiian Islands.
"We found that control of turf algae cover differs by water depth, and herbivore fish numbers were the best indicator of reductions in turf algae cover," Foo said. "Smaller fish exerted greater control on turf algae than larger fish."
A mixture of many algal species and usually less than 2 cm (less than 1 inch) in height, turf algae grows quickly and occupies new spaces on the reef. It can also overgrow and kill coral. Herbivores protect coral by grazing on the turf algae, reducing their overall cover, like cattle on a grass pasture.
Prior to this study, the role of herbivorous fish in controlling algae was well known, but there was limited understanding of how this role changed by reef depth and with different types of fish. The new study revealed patterns between different types of herbivore fish — scrapers like parrotfish, browsers like angelfish and grazers like tangs — and their relationship with how much turf algae covered the ocean floor on shallow, mid and deep reefs.
"Overgrown algae is a critical issue for coral reefs globally," said Greg Asner, study co-author and director of of the center. "This research sheds new light that directly supports the need for conserving herbivore reef fish in a warming climate, for reefs that otherwise will continue to lose to turf algae."
The fish surveys were conducted by National Oceanic and Atmospheric Administration divers who counted, sized and classified fish at each site. They also estimated what covered the ocean floor, allowing the researchers to distinguish between coral and different types of algal cover. With these surveys, the ASU team investigated factors related to fish and turf algae, including how the composition of herbivorous fish changed at different depths and how fishing intensity changed across depths.
"Our findings also indicate that fishing on deeper parts of Hawaiian reefs may be the most detrimental because deeper reefs are naturally inhabited by fewer fish compared to shallower reefs," Foo said. "So deeper reefs would be more vulnerable to fishing pressure on herbivores".
The findings provide new input to reef managers in Hawaii and beyond. Herbivore fish management is a key strategy that can reduce turf algae and boost coral survival. While past management has often focused on the total biomass of herbivore fish present on a reef, the new research indicates that the number of fish — literally the number of mouths on the reef — is the more important goal in the effort to battle turf algae and to protect corals in a warming climate.
The ASU Alumni Association Legacy Scholarship encourages a family tradition of attending Arizona State University and celebrates that tradition with scholarships. Through the generous support of donors, the ASU Alumni Association was able to award 56 Legacy Scholarships to 10 seniors, 17 juniors, six sophomores and 23 freshmen for the 2021–22 school year.
MORE: See photos from the Legacy Breakfast
On Monday, Aug. 16, the ASU Alumni Association welcomed the scholars and their families with a breakfast at Old Main on the Tempe campus. Download Full Image
The Legacy Scholarship fund was established in 2010 to support family members of Sun Devil graduates and foster legacies at ASU. Since then, support for this scholarship fund has grown and the Alumni Association has been able to expand the number of scholarships awarded from three students the first year to 56 students this year. Each recipient will receive $1,200 for the 2021–22 school year to aid in pursuing their academic career at ASU.
Christine K. Wilkinson, president and CEO of the ASU Alumni Association, welcomed the scholars and their families to the breakfast on Monday morning. Her advice to the students was to "get involved in university-wide activities."
"Attend a football game or experience a show at Gammage," she said. "Take advantage of all that your college has to offer including research, internships and learning opportunities. You can follow a dream and make it happen, and that's why this scholarship is offered."
More than 250 Sun Devils applied for the Legacy Scholarship, and ASU alumni from around the world volunteered their time to review the applications. The 56 scholar recipients were chosen based their academic success, a strong commitment to community service and/or university involvement, and achievement of their personal and educational goals.
"This scholarship would not be possible without the generous donations and support from Sun Devils," said Alissa Serignese, vice president of the Alumni Association. Speaking to the parents, grandparents, godparents and future alumni, she asked for their help in growing this scholarship and the tradition of Sun Devils graduating Sun Devils. "I hope you will donate to the fund, bring awareness to the Legacy Scholarship by telling your network or volunteer your time by reviewing applications."
Learn more about the ASU Alumni Association Legacy Scholarship and how to become a donor.
Congratulations to the 2021–22 Legacy Scholar recipients.
- Victoria Adam, sophomore, Herberger Institute for Design and the Arts.
- Gabriella Alessio, senior, Ira A. Fulton Schools of Engineering.
- Wyatt Appel, senior, W. P. Carey School of Business.
- Lauryn Armstrong, sophomore, Ira A. Fulton Schools of Engineering.
- Camille Avila, senior, The College of Liberal Arts and Sciences.
- Maddox Berkson, freshman, W. P. Carey School of Business.
- Ryan Bieniek, junior, The College of Liberal Arts and Sciences.
- Blake Burford, junior, W. P. Carey School of Business.
- Emma Byrd, junior, The College of Liberal Arts and Sciences.
- Matthew Chismar, sophomore, The College of Liberal Arts and Sciences.
- Isabella Colon, junior, Mary Lou Fulton Teachers College.
- Owen Connell, freshman, The College of Liberal Arts and Sciences.
- Jillian Cote, junior, W. P. Carey School of Business.
- Isabella de Sousa Proulx, freshman, Herberger Institute for Design and the Arts.
- Megan Dye, junior, Edson College of Nursing and Health Innovation.
- Isabel Gonzales, freshman, College of Health Solutions.
- Kai Halland, freshman, Ira A. Fulton Schools of Engineering.
- Joseph Hand, junior, Ira A. Fulton Schools of Engineering.
- Karson Herder, freshman, Ira A. Fulton Schools of Engineering.
- Ashley Hill, freshman, Ira A. Fulton Schools of Engineering.
- Benjamin Hill, freshman, Mary Lou Fulton Teachers College.
- Nolan Hoiby, junior, Ira A. Fulton Schools of Engineering.
- John Hubert, freshman, Ira A. Fulton Schools of Engineering.
- Emily Hudson, freshman, Ira A. Fulton Schools of Engineering.
- Robert Huerta McWhirter, sophomore, Ira A. Fulton Schools of Engineering.
- Ryan Humble, junior, W. P. Carey School of Business.
- Ronald Johnson III, freshman, The College of Liberal Arts and Sciences.
- Angelicafawn Kemp Shaw, junior, Watts College of Public Service and Community Solutions.
- Camden King, junior, W. P. Carey School of Business.
- Jude Kolodisner, junior, The College of Liberal Arts and Sciences.
- Daniel Korfist, freshman, The College of Liberal Arts and Sciences.
- Samantha Korfist, freshman, Ira A. Fulton Schools of Engineering.
- Adam Kurth, freshman, The College of Liberal Arts and Sciences.
- Chloe Leff, senior, The College of Liberal Arts and Sciences.
- Jake Lofton, freshman, W. P. Carey School of Business.
- Paige Lottman, junior, Ira A. Fulton Schools of Engineering.
- Brian Lynch, senior, Ira A. Fulton Schools of Engineering.
- Sydney Marsh, freshman, W. P. Carey School of Business.
- Rianna Murrietta, freshman, College of Health Solutions.
- Jadyn Ocken, freshman, Ira A. Fulton Schools of Engineering.
- Anya Pressendo, senior, The College of Liberal Arts and Sciences.
- Isaac Root, freshman, Ira A. Fulton Schools of Engineering.
- Sophia Ruiz, freshman, College of Health Solutions.
- Ian Sherwood, freshman, The College of Liberal Arts and Sciences.
- Sarah Shick, junior, The College of Liberal Arts and Sciences.
- Tyler Shurley, sophomore, Ira A. Fulton Schools of Engineering.
- Savannah Skarecky, junior, W. P. Carey School of Business.
- Mackenzie Taylor, senior, W. P. Carey School of Business.
- Nathaniel Thompson, senior, W. P. Carey School of Business.
- Vedika Tripathi, junior, Ira A. Fulton Schools of Engineering.
- Acacia Wastchak, senior, Thunderbird School of Global Management.
- Alicia Werner, sophomore, Herberger Institute for Design and the Arts.
- Sean Williams, freshman, Ira A. Fulton Schools of Engineering.
- Kasey Wochner, freshman, Herberger Institute for Design and the Arts.
- Kyle Wozniak, junior, W. P. Carey School of Business.
- Clarissa Yosick, senior, W. P. Carey School of Business.
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