Coral reefs are in trouble. I mean, every ecosystem is in trouble, but coral reefs especially: ocean acidification, white band disease, rising sea temperatures, pollution, and overfishing, to name just a few, are killing reefs throughout the tropical and subtropical marine world. And as the coral itself dies, the entire lush ecosystem around it dies as well.
One possible solution lies in a technology more often used to create little plastic toys and architectural models: 3-D printing. In recent years, 3-D-printing technology has expanded to new materials, including aluminum, stainless steel, and titanium. One Australian company, Reef Design Labs, is using 3-D-printed nontoxic, sturdy ceramic to create a new base for coral —and coral reef ecosystems — to bounce back. 3-D-printed ceramic is pretty new, having only sprung up in 2016, and Reef Design Labs installed the first large-scale 3-D-printed ceramic reef in late August.
Coral reefs are formed when free-swimming coral polyps (squishy invertebrates, related to sea anemones) stick onto a rock or other hard surface, usually near land and almost always in warm water. They secrete a hard anchoring substance, made of calcium carbonate, and stay there for the rest of their lives. Other polyps build on that anchoring substance, and then more polyps build on that, and the baby reef grows into (hopefully) a large reef, which provides shelter for various animals, and in turn draws predators looking for food, creating an entire system.
The coral is the basic building block of a coral reef, and if the coral dies, all the other animals will desert the area, finding little protection or food there anymore. This is happening at a terrifying rate; it’s estimated that half of the Great Barrier Reef, the largest such system in the world, has died since 2016.
Kick-starting a rebuild process is not a new one. Environmentalists and governments have been sinking all kinds of stuff for decades, hoping that a new base will attract new coral polyps to attach and form a reef. There are lots of these: sunken ships, decommissioned tanks just hurled into the ocean, art installations. The goal is to replace the structures of the coral reefs, which have died off, and sometimes to implant corals onto them, creating a new, fresh habitat for animals and hopefully attracting new polyps to settle there.
Sometimes they work. Sometimes they don’t. One example: In the early 1970s, a Florida company proposed an artificial reef made of over 2 million used car tires, though mostly the proposal was designed to lure game fish. It was a wild environmental disaster; the tires came loose of their moorings and bashed into existing reefs.
The chief problems with artificial reefs are pollution and sub-optimization. Sunken ships and cars can release all kinds of nasty chemicals — PCB, heavy metals — as they decay in the sea. There’s also the problem that coral reefs are often intricately shaped, with delicate hiding holes and caverns and pathways to provide shelter for animals. Statues like Florida’s Christ of the Abyss, while pretty cool to take pictures of, don’t necessarily do a great job.
More recently, 3-D printing has been used to create more realistic, organic shapes of artificial reefs that couldn’t be made, at least not affordably, from other manufacturing methods. Reef Design Lab submerged its first 3-D-printed reef in the Maldives this summer.
Reef Design Lab’s reef is made of extruded ceramic, a material that’s only been available for 3-D printing in the past few years. Typically this is done by extruding a ceramic resin, rather than the plastic which is more common with 3-D printers. After printing, the ceramic has to be fired, just like a ceramic vase. (The company has in the past printed reefs out of sandstone.) The entire reef isn’t printed at once; instead, as Mongabay notes, it’s printed in blocks, like Lego, which are assembled underwater. Research has shown that ceramic is a great material for reefs: it’s stable, strong, nontoxic, and poses no pollutive threat to animals.
These particular reefs, which took only 24 hours to print, are actually modeled to look like species of native corals, a distinctive honeycombed, pock-marked design that scientists hope will attract new fish.
But it’s also probably worth noting that while artificial reefs do sometimes work to attract animals, they don’t necessarily solve the fundamental problems facing reef environments. Artificial reefs don’t don’t bring the sea temperatures back to previous levels; they don’t halt pollution; they don’t reduce overfishing. They are a step, but not the only one.