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Coral reefs are a vital part of the natural world. About one-third of all marine species depend on coral reefs to survive, and an estimated one billion people worldwide depend on them for sources of food or income. As coral reefs face an increasing number of threats, scientists have developed clever ways of stimulating reef growth through 3D printing technologies.
What are Coral Reefs?
Coral reefs are built up over hundreds by thousands of tiny “reef-building” coral polyps. They secrete layers of calcium carbonate beneath their bodies and, over time, the reef structure develops. They are home to a huge range of marine life and are considered the most biodiverse ecosystems on the planet, forming symbiotic relationships with millions of different species.
Issues Facing Our Coral Reefs
Our climate is rapidly changing, largely due to human impact on the natural world. These changes are causing destruction to many of our coral reefs around the world. With specific requirements of temperature, pH, salinity and water purity; they are highly sensitive to even the smallest of alterations. One of the biggest threats is coral “bleaching”: this occurs as surrounding ocean temperatures rise. The warmer water causes a stress reaction in the coral which forces them to eject the living algae inside them. They need these algae to feed, and so this ejection ultimately causes both parties to die. What’s left behind is a ‘bleached’ calcium carbonate skeleton. In 2017, it was announced that over half of the Great Barrier Reef off Australia’s northeast coast is believed to be ‘dead’ from bleaching. Researchers concluded that the surrounding temperatures rose too much for too great a time for the reef to recover. This discovery was one of the catalysts for the explosion of research conducted on coral reef systems around the world.
3D Printing Artificial Reefs
New developments in 3D printing have given way to the creation of artificial reefs. The first 3D printed reefs were installed off the coast of Bahrain back in 2012 by Reef Arabia. Using large, printed concrete blocks and barges for transportation, over 3000 artificial reefs have been created in the Persian Gulf. Over time, a whole host of marine life is attracted to the submerged structures, bringing life and biodiversity back to the area once more.
More recently in 2018, Australian firm ‘Reef Design Labs’ have successfully installed a fully 3D-printed reef in the Maldives. Their novel Modular Artificial Reef Structure (MARS) uses hollow blocks of ceramic which can be cast into complex shapes and easily fit together as a modular structure. Each unit is printed and molded-in ceramic, which is similar to natural calcium carbonate found in natural reefs. Their designer, Alex Goad, has also created 3D printed oyster reefs to aid with the North Sea oyster regeneration projects. They were printed using Enrico Dini’s large-scale D-Shape 3D printer and weighed over 500kgs a piece; very different to the small, LEGO-like pieces of the MARS project but designed to withstand the harsher waters of the North Atlantic.
Benefits of Printed Reefs
Whilst 3D printed reefs won’t protect against the threat of rising temperatures or a change in pH; their relatively quick and easy construction offers an invaluable platform for marine research, as opposed to waiting hundreds of years for the growth of conventional reefs. Within minutes of installation, the MARS module had attracted curious fish to the bumps and curves of the ceramic reef which mirror their natural home. It is much more difficult and costly to achieve such complex shapes through alternative manufacturing methods, making 3D printing the most obvious contender for artificial reef research.
Over the last four decades, coral bleaching events have become significantly more frequent and is set to become the norm, with figures rising from 8% affected corals in the 1980s to 31% in 2016. It is hoped that the printed structures will attract free-floating coral polyps and, in turn, complex reef systems will develop. This will allow researchers to better understand reef dynamics, and how best to protect them. Although it will take several years for the coral and other species to populate the artificial structures, these early experiments suggest that 3D printed reefs hold huge potential, and may help to alleviate some of the irreversible damage done to our oceans’ natural reefs.
Sources and Further Reading
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