An ink that boosts coral settlement by 20 times could help rebuild reefs worldwide

With coral reefs in crisis due to climate change, scientists have engineered a bio-ink that could help promote coral larvae settlement and restore these underwater ecosystems before it's too late.

In a paper published in Trends in Biotechnology, researchers demonstrate that the ink could boost coral settlement by more than 20 times, which they hope could contribute to rebuilding coral reefs around the world.

Biologists have recently discovered that certain rocky pink algae, called crustose coralline algae (CCA), play an important role in attracting coral larvae and encouraging them to settle on the reef. It appears that CCA emits metabolites into the surrounding water, and coral larvae follow these chemical signals.

Inspired by this finding, Wangpraseurt and his team, including first author Samapti Kundu at the University of California San Diego, developed a transparent ink material infused with metabolites derived from CCA. Dubbed SNAP-X, the ink slowly releases these natural chemical cues into seawater over the course of a month. By applying SNAP-X to rocks or other surfaces, researchers can create an inviting microhabitat that helps coral larvae settle and grow.

The team tested SNAP-X outdoors using natural seawater and continuous water flow to simulate the ocean environment. They found that the larvae of Montipora capitata, a primary reef-building coral in Hawaii, were 20 times more likely to settle on substrates sprayed with SNAP-X, and the settlements became denser when the team increased the concentration of the metabolites in SNAP-X.

Image source: Kundu et al. (2025), Trends in Biotechnology.