Biodegradable Coral Defenders to protect juvenile corals

In an effort to enhance coral restoration, the Florida Aquarium and the Florida Fish and Wildlife Conservation Commission’s Fish and Wildlife Research Institute (FWC-FWRI) have launched a pilot project deploying the Coral Defender, a biodegradable, 3D-printed device designed to protect newly outplanted corals on Florida’s Coral Reef from predatory fish.

During a recent two-day restoration mission, divers from the Florida Aquarium and FWC outplanted 660 juvenile corals across four reef sites within the Florida Keys National Marine Sanctuary. The species included grooved brain corals, ridged cactus corals and symmetrical brain corals. To evaluate the Coral Defender’s effectiveness, scientists placed the protective devices on half of the outplants while leaving the rest exposed for comparison.

The Coral Defender is designed as a tripod structure that prevents fish such as parrotfish and triggerfish from damaging young corals. While these fish play a crucial role in reef ecosystems by consuming algae, they can also harm fragile, newly outplanted corals. “Fish predation on new outplants usually happens within the first two weeks after outplanting,” said Brian Reckenbeil, Coral Restoration Manager at the Florida Aquarium, in a prepared statement. “We hope the Coral Defenders will naturally degrade within three to six months, or faster. We designed the structures so the legs are hollow, encouraging the material to break down from both the inside and outside.” 

Coral Defender 3D printer. Photo provided.

The Coral Defender is made from polyhydroxyalkanoate (PHA), a biodegradable material that decomposes into carbon dioxide and water in marine environments. The material was first tested for predation protection at Nova Southeastern University, and later approved for trial use by the Florida Keys National Marine Sanctuary.

The pilot project is funded through a State Wildlife Grant to the FWC and builds on prior methods, such as using bamboo skewers to deter fish from newly planted corals.

To assess the effectiveness of the Coral Defender, FWC researchers will monitor the corals at regular intervals over an 18-month period, examining predation rates, material degradation and overall coral survival. The study will also test how different attachment methods impact the structure’s longevity, with half of the Coral Defenders installed using marine epoxy and the other half with cement. Findings from the project may lead to design modifications, such as adjusting height, leg structure or color, to further improve deterrence.

Coral reefs are facing unprecedented challenges due to rising ocean temperatures, disease and human activity. The Florida Aquarium operates one of the nation’s largest coral breeding facilities, growing thousands of juvenile corals each year for restoration projects. By fostering genetically diverse coral populations, the Aquarium and its partners hope to improve the long-term resilience of Florida’s Coral Reef.

If successful, this biodegradable technology could significantly improve coral survival rates and contribute to the broader effort of restoring and sustaining reef ecosystems.