Coral reefs make up less than one-quarter of 1 percent of the Earth’s surface,¹ yet supply resources worth an estimated $375 billion annually, according to the International Union for Conservation of Nature (IUCN).² More than 500 million people around the world depend on coral reefs for protection from storms, food, jobs and recreation, and they provide a home to more than 25 percent of fish species and 800 hard coral species.

As for their importance to their surrounding ecosystems, it is immense, and the sheer diversity of species that depend on coral reefs for spawning, breeding and feeding is equally impressive. There are 34 recognized animal phyla, for instance, and 32 of them are found on coral reefs (even rain forests count only nine different phyla among their midst).³

Sometimes referred to as “rain forests of the sea,” it’s estimated that coral reefs may support up to 2 million different species and act as essential nurseries for one-quarter of fish species.

Coral reefs also serve as carbon sinks, helping to absorb carbon dioxide from the environment, and represent an irreplaceable source of protection for coastal cities. Their importance as a food source is also considerable, as healthy coral reefs can provide about 15 tons of fish and other seafood per square kilometer (.38 square mile) per year.⁴

Unfortunately, corals are in severe decline. According to conservation organization World Wildlife Fund (WWF), two-thirds of coral reefs worldwide are under serious threat and another one-quarter are considered damaged beyond repair.⁵ There may, however, be hope, even for damaged reefs, as new technology offers a chance for reefs to regrow at a surprisingly fast pace.

Biorock Technology Restores Coral Reefs

In 2000, it was stated at the International Coral Reef Symposium that about 94 percent of Indonesia’s coral reefs were severely damaged. This included Pemuteran Bay, where the once-thriving coral reef was largely barren. Biorock technology proved to be the answer, restoring the reef in just over a decade:

“Pemuteran formerly had the richest reef fisheries in Bali. The large sheltered bay was surrounded by reefs teeming with fish. The natural population increase was greatly augmented by migration of fishermen from Java and Madura, where inshore fisheries had been wiped out by destructive over-exploitation.

Destructive methods, like use of bombs and cyanide followed their use in other islands, and steadily spread until most of the reefs had been destroyed. The offshore bank reefs that had been dense thickets of coral packed with swarms of fishes, were turned into piles of broken rubble, nearly barren of fish.”⁶

The Karang Lesteri Project, highlighted in the video above, began in June 2000, when the first “coral nursery” was built at the site. Ultimately, 70 Biorock coral reef structures of different sizes and shapes were planted in the area, restoring the area’s diversity and ecosystem. Formerly known as Seament and Seacrete, Biorock was developed by the late professor Wolf Hilbertz and scientist Thomas Goreau, president of the nonprofit organization the Global Coral Reef Alliance (GCRA).

Projects are now being operated in Indonesia, Bali, Jamaica, the Republic of Maldives, Papua New Guinea, Seychelles, Phuket, Thailand and elsewhere. The technology starts with metal structures that are planted into the reef. Transplanted fragments of live coral (that have been damaged by storms, anchors or other mishaps) are attached and the structure is fed low-voltage electricity to accelerate the growth process. GCRA explains:⁷

“The Biorock® process … is a new method that uses low voltage direct current electricity to grow solid limestone rock structures in the sea and accelerate the growth of corals providing homes for reef fish and protecting the shoreline. The electrical current causes minerals that are naturally dissolved in seawater to precipitate and adhere to a metal structure. The result is a composite of limestone and brucite with mechanical strength similar to concrete.

Derived from seawater, this material is similar to the composition of natural coral reefs and tropical sand beaches … This patented process increases the growth rate of corals well above normal, giving them extra energy that allows them to survive in conditions that would otherwise kill them. At the same time these structures attract huge numbers of fish, and also provide breakwaters that get stronger with age.”

GCRA states that Biorock reefs grow at a rate of 1 to several centimeters of new rock per year, which is about three to five times faster than normal. While artificial reefs, which are sometimes made by sinking ships, planes, cars, concrete or other man-made materials, will sometimes attract fish and sponges that settle on their surface, the Biorock reefs ultimately turn into true, living coral reefs, courtesy of the growth of limestone. According to GCRA:⁸

“Coral larvae, which are millimeter-sized freely-swimming baby corals, will only settle and grow on clean limestone rock. This is why conventional artificial reefs made of tires or concrete rarely exhibit hard coral growth. But, when these coral larvae find a limestone surface, they attach themselves and start to grow skeletons. Mineral accretion is exactly what they are searching for. As a result, there are very high rates of natural coral settlement on Biorock structures.”

Is Biorock Sustainable, and Does It Withstand Hurricanes?

Funding to take Biorock to the next level is limited, with most projects so far acting as pilot projects to demonstrate how the process works. And some coral reef experts, such as Rod Salm, senior adviser emeritus with the Nature Conservancy, have suggested the process is too cost prohibitive to work on a large scale.⁹ Others have pointed out that its dependence on electricity could also be problematic environmentally, although some of the structures are powered via solar panels.

Further, GCRA evaluated damage to the structures in the Caribbean after hurricanes Hanna, Ike and Irma and found them to be remarkably unfazed. While even large shipwrecks in South Florida were damaged or moved during hurricane Andrew, for instance, the Biorocks’ open frameworks allowed water to flow through the structures, sparing them the brunt of the damage.

“For growing corals, we make open frameworks, so the corals can benefit from the water flow through the structure, just as they do in coral reef,” GCRA notes. “As a result of their low cross section to waves, they dissipate energy by surface friction as waves pass through them, refracting and diffracting waves rather than reflecting them. Their low drag coefficient means that they survive waves that would move or rip apart a solid object of the same size.”¹⁰

In research published in the journal Revista de Biologia Tropical by Goreau and colleagues, it’s noted that artificial reefs are often discouraged in shallow waters because of concerns that they could damage surrounding habitat during storms. However, in the case of the Biorock restorations, “the waves passed straight through with little damage,” and the researchers said the “high coral survival and low structural damage” after hurricanes suggests the process is effective even in areas that may be hit by storms.¹¹

Another study by Goreau, published in the Journal of Marine Science and Engineering, suggests Biorock electric reefs are able to grow back severely eroded beaches in just a few months. The study noted:12

“Biorock reefs stimulate settlement, growth, survival, and resistance to the environmental stress of all forms of marine life, restoring coral reefs, sea grasses, biological sand production, and fisheries habitat. Biorock reefs can grow back eroded beaches and islands faster than the rate of sea level rise, and are the most cost-effective method of shore protection and adaptation to global sea level rise for low lying islands and coasts”