Team Effort Uses 3D Printing to Restore Coral Reefs

Coral reefs are the most diverse ecosystems on Earth, with thousands of animal and plant species living in their colorful ocean-floor habitats. These reefs are in quite a bit of trouble currently, however. In the past 30 years, 50 percent of the world’s coral reefs have died and if changes aren’t made to slow the progression of climate change and curb other human-caused damage to the reefs, 90 percent of them may die in the next century. Coral reefs aren’t just vital to the plants and animals that call them home, but to humans as well – they provide a lot of income through tourism and fishing, as well as protecting coastlines during violent storms.

Saving them, therefore, is critical, and involves some human intervention at this point. Coral are sessile animals, meaning that they take root like plants but capture their food from the ocean water. Coral polyps root themselves in ocean rocks, gradually reproducing and growing until they form the lush, brightly colored reefs that people travel thousands of miles to see. It’s a slow process, though – coral reefs grow by centimeters each year, taking thousands of years to become large and thriving. Right now, coral reefs don’t have thousands of years, so they need our help.

Several organizations have been trying to help coral by 3D printing artificial reefs and sinking them in the ocean in hopes of attracting free-floating coral polyps to embed themselves and begin reproducing. An organization called SECORE International (Sexual Coral Reproduction) is also using 3D printing, but taking a more hands-on, aggressive approach. SECORE is a nonprofit global network of scientists, public aquarium professionals and local stakeholders working to protect and restore coral reefs. Along with its partners, which include the California Academy of Sciences (CAS) and the Nature Conservancy, SECORE is developing restoration processes that leverage the natural reproductive habits of coral.

Certain coral species naturally broadcast egg and sperm cells, which are collected by SECORE, fertilized, and then raised in tanks until they become freely swimming larvae. Those larvae are then introduced to 3D printed “seeding units” that resemble places on natural reefs where coral would attach. Once the coral have embedded themselves, the seeding units are planted on reef areas in need of restoration.

It’s an effective approach, but a costly one, unfortunately.

“One of the ways SECORE is aiming to reduce these costs is by designing seeding units that do not need to be manually attached to the reef, but rather can be sown from a boat or other method, similar to how a farmer would sow seeds in a field,” said SECORE Project and Workshop Manager Aric Bickel.

3D printing is another way to keep costs down, as well as to rapidly produce the seeding units. SECORE aims to produce a million of the units by 2021, and hundreds of thousands of units annually by then. Phase One of the project is taking place in the Caribbean, with research and training hubs in Mexico, Curaçao and the Bahamas.

“3D printing allows us to do a bit of rapid prototyping. We were looking at several different materials, and 3D printing allows us to print a variety of materials,” Bickel said. “It also saves the cost of having to make molds or castings which, particularly for the initial prototypes, would be a significant amount of money invested.”

CAS is one of SECORE’s primary funding providers, and because SECORE is a small team with limited engineering capabilities, CAS turned to the Autodesk Foundation, with which it looked into various design firms for help with the development of the seeding units.

“In collaboration with the Foundation, we reached out to several design firms,” Bickel said. “Emerging Objects seemed like they would be the best folks to help us out with this next design phase and hopefully with the iterative design phases as we go forward.”

One of the main challenges SECORE has been having is finding the best material and design combination for the seeding units. Not just any shape can be used – the units need to be able to wedge themselves into the reefs without manual assistance. The material is an issue, too. SECORE had been using rough cement for the seeding units, but that material worked a little too well – in addition to attracting corals, it also attracted quite a few competing organisms.

“One issue was with competition from other species on the units themselves,” said Bickel. “What the trials showed is that a slicker surface will cut down on that potential competition. The needle that you have to thread here is having a surface that’s rough enough for corals to settle on and to attach to but smooth enough that it’s not a good location for other organisms such as sponges and algae to attach to.”

Several years of trials and experiments revealed ceramic to be a good potential material for the seeding units. Emerging Objects has plenty of experience in the experimental use of 3D printed ceramic, but needed to be able to 3D print the material on a large scale, so the company reached out to Boston Ceramics for help.

“Boston Ceramics is one of the few companies we’re aware of in the world that can potentially meet some of the demands for the number of substrates we’ll be using,” said Bickel.

The team used Autodesk Netfabb to design the original shape, a tetrapod, for the seeding units, and has been experimenting with other designs that are better suited to landing and wedging themselves in the surfaces of the reefs and protecting the larvae. One of those designs looks like a ninja throwing star.

“The question we posed to our working group was, ‘Can you give us your best impression of what promotes coral larvae to grow, and what’s going to allow them to survive in the ocean as they grow up in these early life stages?'” said Bickel.

The SECORE project is not one of immediate gratification. The organization grows its corals from embryos in small conglomerations of cells, and depending on the species, it can take several years for the corals to become sexually mature. In earlier life stages, however, the coral can still provide habitats for fish and other species.

“It’s definitely an investment in the future,” Bickel said. “I think that with really complicated ecosystems, we’re talking many years before you start seeing comparable structure return to areas that are being restored. The main focus at the moment is, can we improve our methods and our technologies to upscale this type of restoration to the levels needed to counteract the decline?”

SECORE isn’t the only organization working to do so, and the hope is that with enough of them putting effort into restoring coral reefs, the damage can be mitigated and even reversed.

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[Source: Autodesk]