Coral reefs around the world are disappearing at an alarming rate. Pollution, overfishing, coastal development and global warming are all culprits. In the waters near China, 80 percent of the coral reefs have died over the last 30 years and, according to a 2012 study from the Australian Institute of Marine Sciences (AIMS) and the University of Wollongong, 50 percent of the Great Barrier Reef’s coral has disappeared over roughly the same time-frame.
In the Persian Gulf the story is similar. Coastal and offshore development—which often involves large-scale dredging, infilling, coastal modifications, and the creation of artificial waterways—has left the coral reef ecosystem in waters off Dubai, Abu Dhabi, Saudi Arabia and Bahrain severely damaged.
The World Resources Institute estimates that coral cover in Bahrain has dropped from at least 50 percent in the 1980s to nearly zero percent today.
More research, tighter regulation, improved project planning, and better public awareness all need to stack up to prevent more loss. But in the meantime, one organization is set on restoring reefs off the coast of Bahrain.
Reef Arabia designs and manufactures artificial reefs (or constructed reefs, as it prefers to call them) with a view to regenerating precious ocean habitat and improving fish populations, particularly critical in Bahrain, where overfishing has vastly diminished marine life.
The Reef Arabia team—made up of experts from the local area and members of Australia-based Sustainable Oceans International (SOI)—has already submerged nearly 3,000 concrete Reef Balls and custom designed reef units near Bahrain, successfully attracting new fish populations and helping replace some of the reefs Bahrain has lost.
Several of the concrete reef features were designed to reflect Bahrain architecture—a strategy SOI refers to as “culturally sensitive reef design”.
A wind tower—common in the traditional architecture of that region and used to generate natural ventilation—is the centerpiece of the Bahrain reef. The wind tower features are both aesthetically pleasing and functional, specifically designed to appeal to certain fish species which use them for shelter and a place to congregate.
For David Lennon, Reef Arabia team member and director at SOI, the reef is a dream come true.
“I grew up in Saudi Arabia and came to love the marine life of the Gulf. I always admired historic Arab architecture and this project allowed me to tour the old town of Bahrain and select key building designs that would appeal to the fish we were aiming to attract,” Lennon says. “Just like us, fish have preferences for shape and size.”
But reefs formed from concrete molds, even with Lennon at the helm, have their limitations. And that’s why Reef Arabia, in collaboration with SOI, 3D program specialist James Gardiner, and rapid manufacturing experts DShape, is pioneering a new 3D printed reef unit made of non-toxic patented sandstone material. Two of these 3D printed reefs— weighing 1,100 pounds—were sunk off the coast of Bahrain last fall.
“Sandstone, unlike concrete, is closer to a natural earth rock and has a neutral pH surface which makes it more attractive to coral larvae looking for a home,” Lennon says. And the “bumpy, knobby bits” on the sandstone units provide refuge for the common snapper and generate current eddies and multiple horizontal surfaces that coral larvae seem to prefer.
The 3D printing technology has allowed the Reef Arabia team to create the more intricate designs found in natural coral structures. “With 3D printing we can get closer to natural design because of its ability to produce very organic shapes and almost lay down material similar to how nature does it,” Lennon says.
Another advantage 3D printed reefs have over traditionally molded concrete – it’s easier to build diversity into a 3D printed model and much easier to replicated quickly. “We could even generate a 3D image file of a natural reef and then print it,” Lennon says.
Designing diversity into a reef is critical, says Lennon, because diversity in habitat drives diversity of species, a major factor in creating an ecosystem resilient to climate change. Using a 3D printing program the Reef Arabia team can create random variations in the reef units so no two are exactly the same.
It remains to be seen whether Reef Arabia’s 3D printing method will be faster and more cost- efficient in the long-term, but Lennon is hopeful. The prototype reef units took a week to make from scratch. And the actual printing—which involves progressively layering the sandstone with a print head 5m in diameter— takes about a day. The reef units can be printed four at a time. And while concrete is strong and long-lasting, the use of sandstone will cut down on the project’s carbon footprint too, as sandstone requires less fossil fuel than concrete to produce.
So, do the fish really like the 3D printed reefs better than the concrete ones? It’s early days, says Lennon. “But I suspect if we did a detailed count we would find the 3D units have a greater number of different types of fish and the crevices created by the knobby lumps will support more cryptic fish, crabs and shrimp which the [concrete] Reef Balls or other units can’t.
Image courtesy of Reef Arabia