Coral reefs are natural wonders that don’t just mesmerize us with their colorful and diverse ecosystems — they’re also economically invaluable. Industries like aquaculture, tourism, and fisheries rely on them, amounting to a staggering US$375 billion globally each year. That means entire coastal communities depend on the health of local reefs.
But reefs are in trouble. Climate change, pollution, and other human impacts are driving a rapid decline, with scientists warning that up to 90 percent of coral cover could vanish in the next decade. In response, researchers around the world have been scrambling to find solutions. One new approach, from a collaboration between scientists in the U.S., Italy, and the Netherlands, offers a surprisingly elegant fix: a nanogel that makes reefs smell like home.
Their study, published in Trends in Biotechnology, details how a bio-inspired gel mimics the chemical cues coral larvae use to identify ideal habitats. It’s a breakthrough that in combination with other methods could seriously boost coral settlement rates.
Coral Larvae’s Search for Home
Corals might look like underwater rocks, but they’re very much alive — and surprisingly picky when it comes to settling down. Coral larvae float through the ocean, guided by chemical signals released by algae, like the crustose coralline algae, which give clues about the surrounding reef’s health and potential. If the algae send the right signals, the larvae settle and grow. If not, they keep drifting.
Unfortunately, environmental stress is changing the mix of algae in many reef areas, and some of these macroalgae release signals that actually deter coral settlement. So even when we try to help reefs regrow, either by transplanting coral fragments or sexually propagated juvenile corals, the larvae often reject their new homes. That’s where this new nanogel comes in.
Read More: How Volunteers Are Helping Keep Coral Reefs Alive
A Jelly That Tricks Corals
To make reefs more appealing, the research team developed a soft, biodegradable material called SNAP-X, designed to recreate the chemical cues of healthy reefs.
According to the study, SNAP-X is packed with ultra-tiny silica capsules, each smaller than 70 nanometers (for comparison, the average human hair is 80,000-100,000 nanometers wide). These capsules are loaded with the same compounds crustose coralline algae naturally release. To gather those compounds, scientists collected live algae from Hawaii’s Kaneohe Bay, soaked them in seawater, and extracted the resulting chemical “soup” into a concentrated powder.
Next, they mixed that powder into a special light-sensitive gel. Once applied to a reef surface, the gel turns into a jelly when hit with light, locking it in place. The result? A thin, algae-scented layer designed to slowly release attractive molecules over a full month.
In lab tests, larvae were six times more likely to settle on surfaces treated with SNAP-X. In more realistic water-flow conditions, that number jumped to 20 times higher than untreated surfaces — especially when higher concentrations of the nanogel were used. In essence, the team created a synthetic chemical “welcome mat” that tricks coral babies into thinking a degraded reef is a great place to grow.
Boosting Genetic Diversity in Reefs
While promising, SNAP-X isn’t a silver bullet. The gel doesn’t work on its own and needs to be combined with other restoration techniques, like coral propagation and reef structuring. Still, it has serious potential.
Because the compounds encourage sexual reproduction-based settlement, SNAP-X could help boost genetic diversity in reefs, a key for withstanding future stress like ocean warming. The core materials (gelatin and silica) are cheap and widely available, making this approach scalable.
There’s still plenty of work ahead. Researchers don’t yet know which exact molecules in the algae extract are doing the heavy lifting, meaning they must keep harvesting them from live samples. The next step: testing SNAP-X in the wild, with more coral species, in more places.
Read More: There is Still Time to Save the Coral Reefs
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Having worked as a biomedical research assistant in labs across three countries, Jenny excels at translating complex scientific concepts – ranging from medical breakthroughs and pharmacological discoveries to the latest in nutrition – into engaging, accessible content. Her interests extend to topics such as human evolution, psychology, and quirky animal stories. When she’s not immersed in a popular science book, you’ll find her catching waves or cruising around Vancouver Island on her longboard.
