One of the byproducts of a rapidly warming planet is that fish are losing their coral reef homes. With rising water temperatures, the acidification of the ocean, coral bleaching and human activities, fish are increasingly being displaced.
But researchers from the University of Delaware have come up with a way to help homeless fish: 3D printed coral.
3D printed coral didn't negatively impact fish behavior
Published in journal PLOS One, University of Delaware's Danielle Dixson and University of Delaware alumnus Emily Ruhl, demonstrated how 3D-printed objects don't negatively impact how coral-associated fish behave or the survival of coral. The researchers are trying to develop ways to keep the fish on the coral reef after an emergency as well as identify ways to recover the reef.
The researchers also discovered the fish didn't care what materials were used to print 3D corals, which paves the way for the use of environmentally friendly materials to make fake coral rather than relying on plastic. That was an important discovery because the last thing researchers want to do is print out coral that can negatively impact the behavior of the fish.
"If the fish on a reef won't use the 3D-printed coral models as a habitat in the wild, it could place them at greater risk for predation by other larger species," said Dixson, an associate professor in UD's College of Earth, Ocean and Environment's School of Marine Science and Policy in a press release highlighting the research. "If coral larvae won't settle on 3D-printed materials, they can't help to rebuild the reef."
3D printed coral could help reefs recover
To come up with their conclusion, the researchers studied damselfish and mustard hill coral larvae in the presence of a coral skeleton and four corals printed from a 3D printer. The four 3D printed corals were made from different filaments that are cheap and widely available including polyester, cornstarch, and cornstarch combined with stainless steel power. Those two materials are biodegradable.
After placing the fish in a tank with the coral skeleton and the fake coral, they studied the behavior of the fish. The damselfish didn't have a preference between the coral skeleton and the 3D printed coral. The fish' activity levels also remained unchanged regardless of the coral habitat they were given.
"I thought the natural skeleton would elicit more docile (that is, accepting) behavior compared to 3D-printed objects," said Ruhl in the same press release. "But then we realized the small reef fish didn't care if the habitat was artificial or calcium carbonate, they just wanted protection."
Researchers now analyzing data from Fiji
The researchers also discovered mustard hill coral larvae settled at higher rates on the 3D printed coral compared to not having any settlement surface at all which may happen if the coral reef is flattened in a storm. The researchers are now analyzing data from Fiji where they placed 3D printed coral and tiles made from biodegradable cornstarch filaments to see what if anything settles on the artificial tiles.
"Offering 3D-printed habitats is a way to provide reef organisms a structural starter kit that can become part of the landscape as fish and coral build their homes around the artificial coral," Dixson said. "And since the materials we selected are biodegradable, the artificial coral would naturally degrade over time as the live coral overgrows it."