As ocean temperatures rise as a result of climate change, coral reef ecosystems face a high risk of extinction, according to the Convention on Biological Diversity.
Over 50% of corals have been lost in the last 30 years, with a 14% decline in live coral cover in just the last decade. The loss is astronomical, but fortunately, corals are very resilient and adaptive creatures — and biologists are, too.
“I’m over hearing that corals are dying — I’m more interested in what we can do about it,” said Daniel Wangpraseurt, a marine biologist at UC San Diego’s Scripps Institution of Oceanography.
“My lab’s approach is to combine marine biology with physics and bioengineering to come up with new solutions.”
So, they did. Scripps, in collaboration with the university’s Jacobs School of Engineering, just released a study on a breakthrough invention to help repopulate coral reefs: a gel called SNAP-X.
According to the researchers, coral larvae are particularly picky about where they attach and settle down. One of the ways they find their home is by “smelling” chemicals in the water that are associated with healthy reefs.
Wangpraseurt’s team developed a gel that contains nano-particles that slowly release some of the coral larvae’s favorite “smells.”
“Coral are animals, and their larvae are selective about where they are going to attach because once they do, they’re stuck there,” Wangpraseurt said in a statement. “With SNAP-X, we created a material that releases chemical cues that tell coral larvae this is a good place to live.”
The gel is an antidote to a major problem conservationists face when working in reef restoration: Getting coral larvae to settle on degraded reefs (or human-made structures that don’t “smell” like home).
For coral to reproduce, adults spawn gamete cells that form larvae, which drift in the currents and settle on a suitable layer of the reef if environmental conditions are favorable. These adrift larvae also signal to other corals that they have found a good place to reside.
Degraded reefs often lack suitable conditions, which deters coral from repopulating, thus continuing a cycle of habitat loss.
The gel application is a breakthrough in redirecting this process. Scientists have already known that certain types of crusty algae can release chemicals that encourage corals to attach to surfaces, but it’s been hard to translate that knowledge into a practical solution.
“If you just throw these chemical cues in the ocean they dissipate very quickly, making it hard for coral larvae to find their source,” said Samapti Kundu, a postdoctoral researcher at Scripps who worked on the research as the study’s first author.
“We needed to develop something like an extended release drug delivery system that would slowly release these settlement cues in the ocean.”
The research team incubated algae samples collected from Hawaii’s Kaneohe Bay in seawater for 12 hours at a time, later extracting the algae molecules as a concentrated powder.
From there, the algae molecules were placed inside nanoparticles made of silica, the main mineral in sand. From there, the researchers suspended the nanoparticles in a liquid gel that solidifies like Jell-O when exposed to ultraviolet light.
All of these characteristics combined, the team could paint or spray the substance onto a surface and cure it with UV light to allow it to stay.
“Imagine you are able to bottle healthy reef scent,” Wangpraseurt told Science News, “and then you could spray it onto any kind of substrate.”
When the researchers applied the gel in these lab experiments, it increased coral larvae settlement by up to 20 times, compared to untreated surfaces. Once applied, the gel releases coral-attracting chemicals for up to a month.
Their research, published in Trends in Biotechnology, found that SNAP-X released the chemicals long enough to give coral restoration experts the ability to time its application with a coral spawning event.
“I think this material is a breakthrough that can hopefully make a big contribution to coral restoration,” Wangpraseurt said.
“Biomedical scientists have spent a lot of time developing nanomaterials as drug carriers, and here we were able to apply some of that knowledge to marine restoration. This paper highlights that if you bring together ideas from different scientific fields, you can create innovative solutions to tough problems like restoring coral reefs.”
All of the corals included in the study were a single species, the Hawaiian stony coral species Montipora capitata. In future studies, the SNAP-X researchers will see how the gel can work with coral from other regions.
With that in mind, Wangpraseurt believes the material could be easily adapted by loading the gel with chemicals collected from suitable algae sources present in local areas.
They are also curious to see how the gel may support efforts to infuse genetic diversity into reefs, giving them a better shot at coping with heat stress.
To continue these efforts, Kundu and Wangpraseurt are also working with a startup called Hybrid Reef Solutions.
“We want these materials to be used and have a big impact. To me, this means we can’t spend all our time on research — the business side needs development as well,” said Wangpraseurt.
“We are really excited to take this as far as it can go.”
Header image by Francesco Ungaro via Pexels
