Hydrogel helps coral find new home

When baby corals are hunting for a new home, they float around the water column until they find somewhere to settle down and hopefully to grow big and strong. To find a suitable spot to grow, larval corals rely on chemical cues released by their relatives. “But if you're on a degrading reef, a dying reef, or if you are creating an artificial reef, there are none of these chemical signals,” says Daniel Wangpraseurt, an interdisciplinary marine biologist at the Scripps Institution of Oceanography at the University of California San Diego.Wangpraseurt and his lab team have made a gel that they can paint onto reef surfaces to mimic coral suitability signals. They say the gel, which they hope will help coral restoration and engineering, helps achieve a rate of coral settlement up to 20 times as great as that on untreated surfaces (Trends Biotechnol. 2025, DOI: 10.1016/j.tibtech.2025.03.019).Inside the hydrogel is a suite of chemical compounds extracted from crustose coralline algae (CCA). Samapti Kundu, a materials scientist and postdoctoral researcher in the Wangpraseurt lab, says that those chemicals consist mainly of lipid-like molecules, steroid lactones, and carbohydrates. “We encapsulate those chemical cues in a nanoparticle system and mix them with a hydrogel biopolymer–like system,” she says.After spraying, painting, or pipetting the gel onto a substrate for the corals to grow on, the researchers use ultraviolet light to cure and harden it. The hydrogel then slowly releases the chemical cues over a month or more to convince coral larvae to settle on