The value of coral reefs is inestimable. They are essential for ocean life, and a quarter of ocean species depend on them for food and shelter.
They are also incredibly important to humans. Coral reefs provide food, shoreline protection, tourism jobs and dollars, and medicine.
Destruction of coral reefs
Coral reefs, which cover less than 1% of the earth's surface, are in danger, mainly due to the actions of humans. Overfishing, pollution, destructive fishing, invasive species, and the changing chemistry of the oceans are threats to coral reefs.
In some places, coral reefs have already been completely destroyed. And in others, they are not far from destruction.
In response to the dire condition of the reefs, conservation efforts are underway. At the local level, efforts to ensure that fish populations are healthy and that the water around reefs is clean can help improve coral health.
3-D printed coral
Researchers are investigating creative solutions to the coral reef crisis. Danielle Dixson from the University of Delaware (UD) and UD alumna Emily Ruhl are investigating the possibility of using 3-D printed coral to replace or supplement affected reefs.
Like other reef researchers, Dixon and Ruhl's goal is to find a way to keep the right animals present on a reef after it experiences a crisis. When exploring options for 3D printed coral, it is important to choose materials that will not harm the remaining coral or adversely affect the behavior of the fish.
"If fish on a reef don't use 3D printed coral models as habitat in the wild, they could put them at greater risk of being predated by other larger species," Dixson told Science Daily. Dixson is an associate professor in the College of Marine Science and Policy at UD's College of Earth, Oceans and the Environment. "If the coral larvae don't land on the 3D-printed materials, they can't help rebuild the reef."
For laboratory experiments, the researchers made four 3-D printed coral models made of different materials. They placed the models in a tank with a native coral skeleton. The researchers placed damsels in the tank and observed whether the fish preferred one type of coral more than the others.
The results surprised them. The fish showed no preference between the native coral skeleton and the four 3-D printed models. Their level of activity remained the same despite the habitat they were in.
"I thought the natural skeleton would elicit more compliant (ie accepting) behavior compared to 3D printed objects," Ruhl told Science Daily. "But then we realized that the small reef fish didn't care if the habitat was artificial or calcium carbonate, they just wanted protection."
This discovery will allow scientists to use environmentally friendly materials, such as biodegradable cornstarch, instead of plastic when producing 3-D printed coral. There are many concerns about the introduction of more plastic into the marine environment. Using biodegradable and eco-friendly materials will allow the living coral to take its place as it grows stronger.
"Offering 3D-printed habitats is one way to provide reef organisms with a basic structural kit that can become part of the landscape as fish and coral build their homes around artificial coral," Dixson told Science Daily . "And since the materials we select are biodegradable, the artificial coral would naturally degrade over time as the living coral grows."