Could 3D printing help rebuild damaged coral reefs?

A new study has demonstrated that 3D printing may be a viable solution for helping to rebuild damaged coral reefs. It shows that reef fish and settling coral polyps can’t really tell the difference. But just how do you print a coral reef and how successful can it really be?

artificial reef
Artificial reefs like this are becoming more common but can 3D printing be used to help improve the real things

The invention of 3D printing is one of the biggest technological breakthroughs of recent times. As the printers have become more advanced, quicker and cheaper in recent years the number of uses for the technology have skyrocketed. It seems the only limit to what it can achieve is our own imagination. Now researchers from the University of Delaware have been getting creative with the idea and started printing their own corals. The artificial corals can’t replace real corals completely. But the researchers have shown that reef fish and other corals might be able to use the imposters as a building block to help rebuild damaged reefs in the wild. But how does it work? And can it really make a difference?

How to print a reef

The team behind the 3D printouts are Emily Ruhl and Danielle Dixon from the School of Marine Science and Policy at the University of Delaware. They used two different species of coral as models for their 3D replicates, Acropora formosa and Pocillopora damicornis, both of which play an important role in reef building. It was important to use two different shaped corals to eliminate any bias by the reef fish. Each coral skeleton was photographed from 50 different angles which were added up to create a 3D image. Using a 3D printer the pair then printed out copies of the corals using four different materials. Some were plastic based whereas others were made of biodegradable materials. The artificial corals were then left to settle in seawater for a week before the experiments began.

3D corals
The printed corals appear almost identical to the naked eye but are made up of a range of different materials

Can you tell the difference?

The first experiment in the study was to see whether reef fish, which rely on corals for shelter and protection, could tell them apart from the print-outs.  For this they used the reef dwelling damselfish Chromis viridis who importantly show strong fidelity to both species of corals in the wild. The experiment followed what the researchers describe as a ‘cafeteria-style arrangement’ where all four different types of artificial coral were placed in a tank alongside the original coral colony. The researchers then left the fish to explore the tank and noted down any behaviours they saw as well as time spent in and around each coral. For both species of coral they found there was no difference in time spent or behaviours shown between the real and fake corals. Not only that there was no difference between the four types of materials used to make the replicates. This showed that the fish were incapable of telling apart the corals based on what they were made out of.

C viridis
A group of Chromis viridis swimming amongst corals similar to those printed by the researchers

Settling in

When corals reproduce they produce larval offspring that travel to new reefs and settle on other corals where they will begin to self-replicate and grow. The next step was to see if the artificial corals could be used as a base for other coral species to settle on in the same way. To test this the researchers took two tanks, one with artificial corals and an empty one, and released coral larvae into each. The new coral species used was Porites astreoides a very common coral in the Caribbean. The aim was to see how P. astreoides settled in each tank and how long they survived. They found that the larvae settled much more on the artificial coral than the empty tank and were more likely to survive for the entire experiment. There was also no difference between the different types of artificial coral. This demonstrates that the 3D printed corals could be used to settle new colonies onto an existing reef.

next phase
The next step will be to see if the printed corals can be integrated into coral reefs in the wild

Future of 3D

Coral reefs are one of the most threatened ecosystems on the planet. They face multiple threats including coral bleaching, ocean acidification, overfishing, eco-tourism and plastic pollution to name a few. It is therefore more important than ever to come up with new solutions to protect them. Projects such as the Allen Coral Atlas and new techniques such as micro-fragmentation are great examples. But the idea of 3D printing corals may just be the most radical and promising idea yet. This study shows that artificial corals could be used to help rebuild and revitalise damaged reefs with minimal impact on associated marine life. More research on reefs in the wild will be needed to tell for sure, but there is no reason to suggest it will not work. Plus the study also shows that a wide range of different cheap and eco-friendly materials could also be used. As the technology of 3D printing continues to develop, we may even one day be able to create brand new reefs from out of nowhere.

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