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How Effective are 3D Printed Reefs?

Researchers from the School of Marine Science and Policy at the University of Delaware are looking further into the concept of 3D printed models placed in the vicinity of coral and fish, touching on concerns regarding toxicity and chemical leaching. In the recently published ‘3D printed objects do not impact the behavior of a coral-associated damselfish or survival of a settling stony coral,’ authors Emily J. Ruhl and Danielle L. Dixson outline their findings regarding the use of 3D printed models in coral reef behavioral research.

Previous research has been performed regarding 3D printed objects in the environment with success, from studying animal behavior and habitat to using 3D printed shells to offer stability to oyster beds. And you don’t have to live on an island or near the beach to be aware that coral reef systems are in trouble today—often with little left of their once-thriving habitats. Ruhl and Dixson see great potential in 3D printing for ‘advancing the discipline of coral reef behavioral ecology.’

For this study, the team experimented with the use of 3D printed and natural skeletons placed amidst blue-green chromis, along with researching the survival rate of Caribbean mustard hill coral on a 3D printed substrate. In creating the models, they photographed the coral from 50 different angles, using a simple iPhone. After converting the files into 3D designs, they printed the models to life-size dimensions on the following variety of 3D printers:

The researchers then acclimated the 3D printed models in seawater for a week, after which a ‘cafeteria-style arrangement’ was set up:

“All five coral treatments of a single species were arranged in a circular pattern spaced 50cm apart from the corals directly adjacent in a 1.8m diameter tank filled to 45cm. For each trial, coral species and treatment order were randomized. An individual fish was placed into an 18cm diameter mesh cylinder (1cm2) at the center of the experimental tank and left to habituate for 15-minutes (A. formosa n = 29, P. damicornis n = 15). The cylinder’s construction allowed the fish to observe all habitat treatments without having access to them. After the habituation period, the cylinder was slowly raised to begin the 15-minute observation period.”

Replicates of P. damicornis (top) and A. formosa (bottom) control corals 3D printed with nGen, XT, PLA, and SS filament, respectively.

The authors recorded the habitat non-stop, and overall discovered that experimenting with 3D printed objects in situ rendered benign results, demonstrating suitability for assessment of a range of reef behaviors and habits.

“As coral reef ecosystems are highly dynamic environments, field studies are the next step to investigate the efficacy of using 3D printed objects to facilitate ecological research,” concluded the authors.

“While coral settlement studies in situ are typically not disruptive to coral reef systems, 3D printed substrate could allow for novel methodologies in conducting this research. For instance, printed substrate could be designed to compare settlement rates, growth, and survival of different coral species across specific surface complexities or cryptic microhabitats. This information could inform management practices by tailoring efforts to the needs of individual species.”

While many users and researchers today are concerned about the impact of 3D printing on the environment, the technology has been used in many different projects behind helping to save it, from preparing to rid the ocean of plastic waste to removing pollutants from the air and even stopping food waste.

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viridis spent in association with any of the coral habitat treatments (n = 44).

Mean behavioral responses (± SE) by C. viridis when exposed to 3D printed or coral skeleton habitats (n = 12).

[Source / Images: ‘3D printed objects do not impact the behavior of a coral-associated damselfish or survival of a settling stony coral’]

 

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Team Effort Uses 3D Printing to Restore Coral Reefs

[Image: SECORE: Paul Selvaggio]

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.

3D printed seeding units. [Image: SECORE/Valérie Chamberland]

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.”

A diver with a tray of the seeding units [Image: SECORE/Benjamin Mueller]

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.

[Image: SECORE/Valérie Chamberland]

“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.

This elkhorn coral was outplanted by SECORE five years ago. Since then, it has grown into a mature colony, which now spawns with other elkhorn colonies in the waters of Curaçao. [Image: SECORE/Paul Selvaggio]

“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]