There are many requests for mineral accretion projects from marine conservation groups around the world, but unfortunately there is little funding available from governments, international philanthropic agencies or private foundations. a result, most mineral accretion reefs are pilot projects that demonstrate the process. The results are so unexpectedly spectacular that one must see them directly to appreciate their value.

To power the mineral accretion process, a low DC voltage is necessary. The source of this current generally depends upon the environment near the reef. If a ready supply of electricity is available, cables can be attached to the structure. In more remote areas, solar collectors are usually the energy source. These panels will generally be set up on the shore to feed current to the Biorock reef via submerged cables.

Just as a gardener pulls up weeds that would overgrow the flowers, undesirable weedy organisms and certain sponges and algae that could overgrow corals are periodically removed. Organisms that kill corals, such as the crown of thorns starfish and certain coral-eating snails are eliminated. Biorock reefs also need to be periodically checked to ensure that cables and connections are intact.

Artificial reefs are typically made from manmade materials like sunken ships, planes, cars, concrete, rubber tires and trash. On land, this material might be called junk. Although fish will hide behind or within any structure that provides shelter and although certain sponges and soft organisms will sometimes settle on these materials, they never turn into a true coral reef.

Global warming has caused significant reef mortality around the world. The prognosis is that oceans will continue to warm until world leaders recognize the long-term consequences of turning a blind eye to the problem. A few governments have tried to address the problem by building sea walls out of concrete, steel, coral rubble or sand bags. But these materials soon rust, corrode, collapse and need to be rebuilt.

Like an oasis in the desert, all forms of coral life are quickly attracted to Biorock reefs. Many forms of reef life have been observed to be attracted to the structures, and none repelled. However it is the organisms with limestone skeletons, such as corals, clams, oysters, barnacles, tube worms and sand-producing algae that are especially benefited, allowing them to outgrow weedy algae that often smothers and kills corals in polluted waters.

Over 200 square miles of near virgin reef can be found in Bermuda. The warm, nutrient rich waters of the Gulf Stream pass through Bermuda and have led to the formation of the worlds most northerly coral reef. The reef is very healthy, and has not suffered the effects of Diver Damage like some Caribbean locations. Abundant hard corals and sea fans are to be seen, but less sponges than you'll see in the Caribbean.

To build a Biorock reef, an electrically conductive frame, usually made from readily available construction grade rebar or wire mesh, is welded together, submerged and anchored to the sea bottom. Sizes and configurations are infinite and are varied to fit the setting. A low voltage direct current is then applied. (Power sources can include chargers, windmills, solar panels or tidal current generators.

The structure is built from ordinary construction materials typically available almost anywhere in the world. This can include steel rods, pipe, or rebar. Other materials necessary for the project include electrical cables and epoxy or silicone sealants to protect the electric connections. While the main structure serves as the cathode, another electrode, the anode, is a special titanium mesh that does not corrode.

In most coral reef environments, structures sit on limestone bedrock where they eventually cement themselves solidly to the hard bottom. Usually structures are held in place against wave forces by their own weight or by filling them with rocks. In hurricane regions, where there is a tradeoff between how long it takes to get the structure solidly cemented to the bottom and when the first hurricane hits, we drill holes for vertical rebar supports; a couple of feet is usually adequate.

Our divers never damage an existing, healthy reef to populate a Biorock structure. In all cases, we transplant broken fragments of live coral that have been damaged by waves, storms, anchors or by other means. These pieces would almost certainly die as the fragments roll over in heavy waves and become buried in sand.

The longer a project runs, the more corals will grow and be protected from future hot episodes. A project can have its power turned off at any time, but then the special advantages of growth, strength, self-repair, accelerated coral growth and survival will be lost. However, once the structure is sufficiently strong, the power can be reduced to maintenance levels.

In August 1999 the first of two pilot structures was placed in the reef of Sac Bajo, (next to Isla Mujeres, across from Cancun). Shaped like a triangular prism, the reef is approximately 3 meters long and 1.5 meters high. In March 2000 a second structure was placed at the same location, approximately 5 meters away from the first. This structure was named "El Doble Caracol" (twin snail shell), owing to its shape of a double spiral of steel construction mat.

Reefs die for many reasons: rising water temperatures, sewage, eutrophication, disease and negligence. A reef ecosystem that took hundreds of years to grow can be destroyed in a single afternoon by dredging, dynamite or cyanide fishing. Corals around the world have been severely affected by global warming. High temperatures cause corals to turn white (or "bleach"). If it remains too hot for too long, the corals die of heat shock.

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.

Corals grow at accelerated rates with mineral accretion because the electricity flowing through the structure creates chemical conditions (high pH) at the surface of the growing limestone crystals and at the surface of the coral's limestone skeleton, greatly speeding up their growth.

Normally we use shore based DC power sources (chargers, solar panels, windmills etc.) Because of voltage drops in the cable to the structure we prefer to work within 100 yards of the power source. But there is no problem going further if one is willing to boost the voltage at the source to compensate for voltage drops. We have a coral reef structure in the Maldives that is more than 400 meters from shore.

There is no limit to the depth. Normally we build structures in shallow water (5 to 25 feet bottom depth) because corals grow best in brightly lit shallow water, but we also try to have them deep enough that boats can't run into them.

There has been a recent surge of promotion selling "coral calcium pills". Selling ground up coral skeleton as a natural source of calcium is an endlessly recurring scam that hucksters pick up on every few years like clockwork. My colleague Wolf Hilbertz has a bottle of coral tablets someone was peddling in the 1960s. There are many natural sources of dietary calcium that don't require killing corals. It is important to keep a balance between your calcium and magnesium intake.

GCRA is a non-profit, all-volunteer, 501 (c)(3) corporation; donations to Global Coral Reef Alliance are fully tax-deductible. No salaries or board perks are ever taken out of any income raised-100% of funds raised goes directly to studying, building and restoring coral reefs around the world. If you would like to contribute to GCRA's program for saving reefs, please send your tax deductible contributions to: