Reef balls offer one way to protect coral reefs.

Story & Photos By Rachel Craft

On a recent trip to the Turks & Caicos Islands—my first visit, and hopefully not my last—I discovered that half of the Islands’ beauty lies underwater. I swam with hawksbill turtles at Smith’s Reef, spotted moray eels at Bight Reef, and nearly choked on my snorkel when an immense eagle ray soared past me through Triggerfish Reef. But the least expected sight, and the one that most captured my interest, was off of the remote Malcolm’s Road Beach on the western side of Providenciales. As I paddled farther from shore, goggles down, I found myself in an eerie, otherworldly sea of “Reef Balls”: concrete structures designed to grow coral and attract fish.

These Reef Balls—concrete structures designed to grow coral and attract fish—are arranged off Malcolm’s Road Beach on the western side of Providenciales.

At first I wondered if I was looking at some kind of garbage, or perhaps the remnants of some long-lost civilization. I later learned I’d stumbled upon 925 of the largest Reef Balls in the world, each nearly as tall as I am and weighing around 5,000 pounds. These aren’t the only artificial reef structures to have been built in the Turks & Caicos—over the last three decades, countless Reef Balls have popped up all over TCI to create new coral habitat and aid existing natural reefs.

Reef Balls were news to me, but the plight of coral worldwide was not. Reefs everywhere have been struggling under various (mostly anthropogenic) stresses: overfishing, pollution, habitat destruction, climate change. Nearshore reefs are under even more pressure from hundreds of thousands of tourists each year, who cause inadvertent damage by standing on corals, leaving behind trash, or wearing toxic sunscreen.

The loss of our reefs would be a tragedy to anyone who, like me, has experienced the wonder of watching fish in their natural habitat through a pair of snorkel goggles. But sadly, if humans cause reefs to go extinct, that would be the least of our worries. Reefs buffer coastlines from storms, provide jobs through fishing and tourism, and support thousands of species of fish, many of which are key sources of food for coastal communities. Losing coral reefs would mean losing food, income, and protection for roughly half a billion people—including many in the Turks & Caicos. It is clearly in our best interest, not just Mother Nature’s, to do what we can to protect coral reefs. The Reef Balls are one of several ways scientists are tackling this challenge.

While I was excited to see these Reef Balls in action, I was also curious. As a former materials engineer, I’m familiar with the harshness of the marine environment. Few materials can withstand the corrosive salt water for long; most will start to disintegrate after a few years, leaching chemical and particulate pollution into the ocean. Seeing the vast rows of Reef Balls outside Malcolm’s Road Beach, I wondered how they were built to help the environment without causing more harm. The answer turned out to be a relatively simple design—but it took a few decades to figure out.

Although ancient hunters experimented with the first artificial reefs as a way of luring more fish to their nets, using them for eco-friendly purposes was mostly a 20th-century idea. People started to notice how shipwrecks evolved into flourishing man-made reefs, and they got the idea to kill two birds with one stone by dropping garbage into the ocean.

Florida’s Osborne Reef is a prime example: In the 1970s, a huge effort was undertaken to “recycle” over a million car tires by turning them into coral habitat. Unfortunately, what was meant to become the world’s longest artificial reef ended in ecological disaster. We learned the hard way that reefs couldn’t be built from just anything. Tire rubber, for example, doesn’t have the right surface texture to allow coral larvae to attach, and it’s too lightweight to stay in place over many years. All the tires managed to grow was algae, and they floated away after the first storm, creating a massive pollution problem that’s still being cleaned up 50 years later.

Since then, scientists have learned how to build successful artificial reefs. This means using marine-safe materials that can stand the test of time in salt water, such as steel (what most shipwrecks are made of), glass, and cement. Dumping glass bottles and cinderblocks won’t work—these structures must be large and heavy enough to prevent movement during storms. They must have enough surface texture to promote coral attachment, and enough nooks and crannies to encourage fish to take shelter.

The Reef Balls, devised by the Reef Ball Development Group, are made from concrete with a pH similar to seawater, which prevents the balls from decaying. They’re expected to last 500+ years underwater! The concrete’s texture and chemical makeup mimic natural coral limestone, making it an ideal place for coral to attach and grow. It’s also easy to mold into the shapes needed for a successful artificial reef. Reef Innovations built and installed all of the Reef Balls around TCI, including the aptly named “goliath” model at Malcolm’s Road Beach. They make many other sizes and shapes of concrete reef structures, some as small as nine inches high—but their weight distribution keeps them in place even during storms, and their hole patterns are designed so that rough seas actually push the Reef Balls further into the sand.

Some Reef Balls are installed with coral fragments transplanted from imperiled reefs. Others rely solely on “natural recruitment,” meaning they bide their time on the sea floor until coral larvae, drifting past in the current, latch on. Natural recruitment is understandably a slower process, and it depends on how many larvae and nutrients are in the water—relatively few in TCI’s clean, clear water. That’s why the Reef Balls I saw weren’t exactly covered in coral during my recent visit, six years after their 2016 installation. I did see some small yet promising corals growing from the balls, and several fish swimming in and out of the holes, but it will take several more years before the corals grow enough to obscure the Reef Balls beneath. 

The first use of Reef Balls in the Turks & Caicos Islands was in the Grace Bay area in the late 1990s. In a project funded by the Turks & Caicos National Trust, Reef Balls were used to create snorkel trails through Smith’s Reef and Bight Reef to guide snorkelers and minimize coral damage. Shortly afterward, the Department of Environment & Coastal Resources created a separate artificial reef nearby, reducing stress on Smith’s and Bight Reefs by drawing tourists away.

Since then, Reef Innovations has installed thousands of Reef Balls at sites all over the Islands. Most are off of Providenciales, with a few around Grand Turk or smaller islands like Pine Cay. Some are used to transplant corals that are under threat from new construction projects. Others, like the one off Malcolm’s Road Beach, are intended to protect the shore from storms, floods, and erosion—with the added benefit of creating new coral habitat. 

Paddling over those Reef Balls gave me mixed feelings. On one hand, it was a sobering reminder of why we need artificial reefs: because natural reefs are struggling, and (let’s be honest) it’s our fault. But at the same time, it gave me hope. Seeing a thousand Reef Balls sitting patiently beneath the water, with young corals making their tentative way out of the concrete, reminded me that there are plenty of people who love the ocean as much as I do, and they’re doing everything they can to protect it.

Rachel Craft is a Colorado-based writer and recovered engineer who loves all things outdoors. When she’s not busy exploring, she writes fantasy and sci-fi stories for children. You can learn more about her at  www.racheldelaneycraft.com.