This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Coral reefs are renowned for their visual beauty, but for the marine life they support, their sounds may be just as enticing. Two new studies led by UC San Diego's Scripps Institution of Oceanography reveal how underwater acoustic enrichment—the playback of sounds from healthy reefs—can help spur the recovery of degraded coral reefs and their fish communities.
These studies—one focusing on coral larvae and the other focusing on fish larvae—are the first to field-test the effects of underwater sound on fish and coral larvae simultaneously, alongside other restoration technologies including living materials and 3D-printed settlement surfaces. The research took place in Hawaii's Kāne'ohe Bay, located off the island of O'ahu, over several spawning events in 2023 and 2024. "We have demonstrated in a single set of field studies that acoustic enrichment works in increasing the presence of both fish larvae and coral larvae on artificial reef structures," said Scripps Oceanography researcher Aaron Thode, head of the Scripps Environmental Acoustics Lab and lead author of the coral larvae study.
Scripps Oceanography scientists led the studies in collaboration with the University of Hawai'i and other consortium partners of Rapid Resilient Reefs for Coastal Defense (R3D), a project focused on nature-based strategies to reduce wave energy, protect coastlines and improve coral resilience. The newest study, published in Communications Biology, examines how acoustic enrichment affects coral larval settlement—the critical stage when free-drifting larvae search for a place to attach and begin building a reef. The research also demonstrates the potential of living materials and 3D-printed settlement surfaces to enhance coral settlement under natural spawning conditions.
"Our data indicate that when these drifting organisms detect a lot of sound from a reef, it signals to them that this is a good place to settle," said Thode. "Our analysis also provided strong evidence that synthetic chemical cues attract these organisms to reefs." To start, the team collected sounds from a healthy reef environment off O'ahu, Hawaii. Over the course of a lunar cycle, their recorder captured the sounds of fish and numerous other organisms, including shrimp and crustaceans that produce distinctive snapping noises. (Listen to the sounds of a healthy reef under the new moon and the distinctive "purr" of a damselfish.) The researchers then broadcast these recordings from an underwater speaker at the study site—a flat, sandy area off the small island of Moku o Loʻe.
For two weeks, the speaker played the reef recordings from sunset to sunrise. Around the speaker, the team placed 37 artificial structures on the seafloor, at a depth of 4.5 meters (15 feet) and distances from 1 to 42 meters (3 to 138 feet) away. The structures varied in design and surface properties and included engineered microhabitats developed in Scripps researcher Daniel Wangpraseurt's Coral Reef Ecophysiology and Engineering Lab.
These microhabitats were engineered in two ways: through their physical architecture, which created complex, protected settlement spaces, and through their living surface coating, made with BRINK—a bioactive "reef ink" containing living bacteria. BRINK was developed by former Scripps postdoctoral researcher Natalie Levy and colleagues in Wangpraseurt's lab. Discover the latest in science, tech, and space with over 100,000 subscribers who rely on Phys.org for daily insights. d research that matter—daily or weekly.
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