3D-printed ceramic helix structures aid reef recovery and coastal resilience

Researchers at the University of Hawaiʻi at Mānoa have developed and field-tested novel 3D-printed ceramic modules designed to boost survival and settlement rates of juvenile corals. These spiral-shaped microhabitats, named “helix recesses”, mimic natural reef crevices and provide refuge to coral larvae from predation, overgrowth, or dislodgement by water flow, dramatically improving coral restoration outcomes.

While fragmentation and outplanting of mature corals have been successful in some contexts, juvenile corals often fail to survive the early life stages. Larvae may not find suitable settling sites, or may perish quickly after settlement. To overcome this, the Hawaiʻi researchers fabricated small ceramic modules using a 3D clay printer, then fired them into durable structures. Each module is about a foot in diameter and incorporates microscopic spiral grooves or cavities where larvae can settle safely.

In field experiments, the researchers deployed seven distinct module designs at two reef sites in Kāne‘ohe Bay and monitored settlement and survival over a year. The helix recess design outperformed flat and less engineered configurations by orders of magnitude: settlement rates on the helix structures were about 80 times higher than on flat surfaces, and survival of recruits was up to 50 times greater over the year-long study period. Thousands of baby corals were observed clustering in these microhabitats, in contrast to minimal settlement on unmodified surfaces.

The researchers suggest the success stems from the modules’ ability to replicate the “safe spaces” that coral larvae naturally prefer. By recreating this microtopography intentionally, the structures guide larvae to settle in biologically favorable zones. As lead author Jessica Reichert noted: “We wondered if we could recreate these safe spaces in structures that could be easily added to reefs for restoration or built into coastal infrastructure.”