Coral reefs are one of the nature eco-systems that are being affected by global climate change, and scientists are seeking ways to help save the marine life that depends on them for sustenance.

One solution to help improve the health of coral reefs comes from researchers at the University of Delaware, who have found that 3D-printed coral models can supplement depleted coral resources and still help maintain a healthy marine system.

Shown here are 3D-printed coral models of Acropora formosa, a type of coral found in the Indian and Pacific Oceans. The 3D printed models of differing complexity were secured to an area of a reef with low-complexity, then observed to understand which habitat the fish preferred. (Source: University of Delaware)

The team, led by Associate Professor Danielle Dixson, came upon their solution while researching another idea, she told Design News. Dixson is a researcher in the university’s College of Earth, Ocean and Environment’s School of Marine Science and Policy.

“We were initially interested in investigating the role of topographic complexity--how many tiny holes there are for animals to hide in--on coral reefs,” said Dixson. “To do this study, we needed to come up with a way to create more and less topographically complex structures to test our research hypothesis. Using 3D printing allowed us to image a real coral and then add or subtract branches, keeping the relative size the same but changing how complex the print was.”

The team later realized their invention could help solve a real-world problem—to help some of the fish in coral reefs still have places to live in safety. “Coral reefs are under threat from a number of different environmental stressors,” including climate change, tourism damage and boat damage, hurricanes etc.,” said Dixson. “Either way, reefs are often left after a stressful event with less topographic complexity.”

Without this protection, these marine creatures could die prematurely. “Topographic complexity is really important because it provides space for small fish, especially juveniles, and invertebrates to live in,” said Dixson.

A New Solution

Dixon noted there already is a solution being used to replace damaged parts of reefs, but they each have their own drawbacks. “Current restoration methods rely on outplanting coral fragments into reefs that have begun to degrade,” said Dixon.“While there are benefits to this, the coral fragments are often small, and the corals that are fragmented are typically the species that have the best survivorship and the best growth rate after outplanting. These are not necessarily the most important corals or the most structurally complex corals.”

The process also is extremely time consuming because corals growth very slowly, so the fragments need a lot of time to reach a size that can help organisms on the reef, she said. “The 3D prints solve these issues,” said Dixson.

The team tested their solution with damselfish that live in the tropical waters off the island of Fiji. What they found is that 3D-printed objects do not impact the behavior of the damsel fish or the survival of a settling stony coral.

They fabricated their 3D coral in a 3D printer by replicating a coral skeleton using 50 iPhone images of the coral taken from all angles. They printed four different artificial coral models from low-cost, widely available filaments, including polyester and two biodegradable materials--one made from cornstarch and another made from cornstarch combined with stainless steel powder.

The team published a paper on their work in the journal PLOS.

Field Tests and Fish Behavior

In their tests, Dixson and her team discovered that fish showed no preference between materials used to 3D-print artificial corals. This allowed researchers to use a biodegradable corn-based PLA, which naturally degrades over time. The team deployed artificial coral made of this material to help replenish the coral on the Fiji reef, where they are currently observing the results.

The solution is meant to be temporary and promote the growth of natural coral, with the artificial material eventually dissolving and giving way to new corals. “The corals are able to have real coral larvae settle on them and grow into corals, so it is our hope and hypothesis that the corals could be put on a reef and would naturally become covered with live corals,” said Dixson. “Live corals take a long time to grow into a substantial structure, so while they are growing the 3D artificial corals can work as a temporary refuge for fish and invertebrates that rely on complex habitat.”

The team is currently conducting field trials to examine more closely how animals interact with the prints in a natural setting, and expect to base future research using artificial coral on these results.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.