The use of 3D printing could make coral restoration faster and easier. With more advances in this technology, it could be applied to quickly and reliably develop support structures upon which coral can grow.
Increasing pollution and warming oceans have been affecting coral reefs around the world. Measures to restore reefs involve using metal frames or concrete blocks as substrates for coral growth. The ensuing restoration is gradual because corals deposit their carbonate skeleton at a rate of only a few millimeters per year.
Charlotte Hauser and her colleagues have been investigating the use of 3D printing to accelerate the process.
Coral microfragments grow more quickly on our printed or molded calcium carbonate surfaces that we create for them to grow on because they don’t need to build a limestone structure underneath.
Hamed Albalawi, Study Lead Author, KAUST
Essentially, the concept is to offer the corals a head start to enable the reef to recover rapidly. The concept itself is not new. Scientists have tested various strategies to print coral support structures. But a majority of the efforts have involved the use of synthetic materials. Studies using hybrid materials are also underway.
The researchers created and tested a new method called 3D CoraPrint, which involves using a sustainable and environmentally friendly calcium carbonate photo-initiated (CCP) ink that they developed. Tests performed in aquariums have demonstrated that CCP is non-toxic, although the researchers are looking to perform longer-term tests.
In contrast to current techniques that depend on passive colonization of the printed support structure, in 3D CoraPrint, coral microfragments are bound to the printed skeleton to initiate the colonization process. It also involves two different printing methods, both of which begin with a scanned model of a coral skeleton.
The first method involves printing the model and using the print to cast a silicon mold. The final structure is generated by filling CCP ink into the mold. The second method involves directly printing the support structure with the CCP ink.
Both the approaches provide complementary benefits. Although developing a mold implies the structure can be quickly and easily reproduced, the curing process restricts the size of the mold. Direct printing is gradual and exhibits lower resolution; however, it enables individual customization and the development of larger structures.
With 3D printing and molds, we can get both flexibility and mimicry of what’s already going on in nature. The structure and process can be as close as possible to nature. Our goal is to facilitate that.
Zainab Khan, Study Co-Lead Author, KAUST
Albalawi, H. I., et al. (2021) Sustainable and Eco-Friendly Coral Restoration through 3D Printing and Fabrication. ACS Sustainable Chemistry & Engineering. doi.org/10.1021/acssuschemeng.1c04148.