RAISED UP ON ITS HAUNCHES, teeth bared, shoulders hunched, the massive tiger was ready to pounce. As I looked around me, I felt as if I was in the middle of a surreal dream.
Over there, a trio of bicycles leant against each other; over here was a giant hand giving a peace sign, while the metal springs of a mattress lay on the door in between. A huge lotus tower, petals unfolded, stood centre-stage, cocooning a sculpture of a beautiful goddess.
All were covered in a coating of brightly coloured corals, many sporting seafans, sponges and groups of fish as decoration.
I was diving the Biorock Park, starting a few metres off the shore of Pemuteran in north-west Bali, Indonesia.
Biorock was first developed by Professor Wolf Hilbertz in 1979. The German marine architect was invited to Bali by Yos Amerta, a Pemuteran dive-centre owner, after he discovered Professor Hilbertz’s work on sea walls and thought that it might work as an artificial reef. Taking marine biologist Tom Goreau with him, Wolf paid his ?rst visit to Pemuteran in 2000.
Damage has been caused to coral reefs worldwide by a combination of weather, rising sea temperatures, dynamite and cyanide ?shing, building and marine tourism, but attempts were made to build artificial reefs from as early as the 1830s.
This was in South Carolina, where locals experimented with log huts, but the wood rotted and deteriorated before corals could grow on them.
In the 1950s and ’60s ?shermen tried using concrete blocks, tyres, train carriages, coaches, cars, white goods and even toilets. None of these ideas was particularly successful, and it took a long time for corals to colonise them.
Of course, the original arti?cial reefs were shipwrecks, which could grow completely unrecognisable over time and seemed to provide the perfect basis for coral growth.
Many decommissioned vessels are sunk as artificial reef systems, but they have to be located in a area suitable to take a huge structure, and where they won’t damage any existing reefs.
Although fish may start moving into their new home almost immediately, it actually takes three to five years for a wreck to be colonised suf?ciently by corals and plants to sustain and support
a whole wealth of marine species in the same way as a natural reef.
To not only regenerate reefs close to shore but to increase the breeding and spawning grounds of reef ?sh in protected waters, something else needed to be done.

WOLF HILBERTZ HAD
pioneered a technique of passing electrical currents through salt water. Back in 1974 he found that saltwater minerals would slowly form around an electrode, coating it with a material as strong as concrete.
As long as the current flowed, the structure would continue to grow larger and stronger – at a rate of 5cm per year.
It would also be able to regenerate and heal itself if damaged.
Calling this process “accretion”, Hilbertz used the technology in developing countries to grow low-cost sea-walls in the ocean by applying electrical current to submerged conductive structures.
After meeting Tom Goreau, the two began thinking about how the technique might be applied to coral reefs.
They started by using steel reinforcing bars, which were cheap, easy to weld and found everywhere. Simple structures were sunk and anchored in 3-5m. Thick steel-mesh wire later became another biorock structural material.
Two 12V power cables were attached, one connected to a power supply (positive pole) and the other to the structure (negative pole). Electrochemical reactions raised the ph level around the metal and the mineral accretion would start forming within 48 hours. Broken live corals were then tied to the structure.
After three months, the corals were naturally attaching themselves to the structures and growing.
At first, the success rate was only 40%, because those tasked with attaching the corals were either not doing it properly or using dead corals. After extensive training of a small group of locals, however, the success rate in Pemuteran has now reached 75%.
Marine biologists who study the reef regularly have found that the corals grow faster, are stronger, more brightly coloured and have more marine life than natural reefs. It’s a bit like a bionic reef!
Since 2000 more than 70 structures have been sunk off the beach in Pemuteran. Most are very healthy and sport a multitude of different skeleton-building hard corals. Soft corals and sponges are mostly “gardened” off the structures, as they are much faster-growing than hard corals and block the slower-growing but more important reef-building hard corals.
Once the reef has built up sufficiently, the soft corals, seafans and sponges are allowed to grow. As the calcium carbonate coating the structures is so similar to the natural reef substrate, corals freely take to the biorock.
Most of the early structures were either arches or tunnels. A bare mattress was anchored down to see how the coral would take to it, but was the one structure that didn’t work too well, probably because the springs were too tightly packed to allow enough coral to gain a foothold. Being closer to the seabed than the other structures, the flow of nutrients would not have fed the coral as effectively.
Biorock structures can be built in any shape or size. Using common construction reinforcing bars or wire mesh, they can be made very simply by unskilled locals with welding equipment.
Such techniques suit third-world or remote sites, where the reefs have been damaged, especially by destructive fishing methods. Villages can increase eco-tourism and thus income by building artificial reefs, and become less reliant
on fishing.

WHEN TOM AND WOLF
made their first structures in Pemuteran, the power cables would keep disconnecting in big storms because of wave movement.
They also found that trigger?sh liked to bite the cables. But by getting the whole community involved in helping to nurture and care for these reefs, the main industry of Pemuteran has shifted from ?shing to eco-tourism. The community has gone on to win many international awards and prizes, including the United Nations Equator Prize 2012.
Some of the oldest structures have now been taken off the electrical currents, as their reef skeleton is deemed strong enough to support itself. A lot of the original power cables are nearly completely covered in coral growth too.
A beautiful goddess sitting in a giant lotus leaf is the first structure to run on solar power, and more structures are being planned to be supplied in this way.
The cost of keeping an almost-constant power supply (it is shut off for several hours a day to save on electricity) is shared between all the hotels and dive centres in Pemuteran, although Bali Dive Academy is the overseer.
Unfortunately there is no government funding, so an “adopt a baby coral” scheme was founded to help pay for the four regular staff who look after the biorock. Visitors can also pay to have their name made out of wire and attached to one of the structures.
Although Pemuteran was the first place to have biorock structures, I had come across several before my visit there this year. In Lembeh Strait in North Sulawesi, Lembeh Resort has built its own structures. Though not as thickly covered in hard coral, because the electrical current was supplied only for a short period and soft coral ?ourishes on the structures, there are clear signs of a healthy eco-system where none would otherwise have existed.
In Gangga Island near Bunaken, also in North Sulawesi, several structures had been built which, again, showed a very healthy eco-system, although not as much coral growth or marine-life as Pemuteran.
Indonesia has the most biorock projects, in at least six locations, including the two largest reef-restoration projects in the world – in Pemuteran and the Gili Islands off Lombok.
Other projects exist in more than 20 countries, including the Maldives, Caribbean, Seychelles, the Philippines and Thailand. I saw the project in the latter country’s Koh Tao located at Japanese Gardens back in 2012. In conjunction with Save Koh Tao, Big Blue Dive Centre and a consortium of other dive-schools launched their biorock project in 2006, and it was so successful that a newer and larger biorock structure was installed in 2008.
For Koh Tao, an island visited by tens of thousands of divers every year but with only a few dive-sites, this was particularly helpful, because it meant creating a new dive-site.
The mesh-like make-up of the structures makes them particularly suitable for storm-ravaged reefs, such as in the Caribbean. In Grand Turk in the Turks & Caicos Islands, two projects were initiated in the shallows at around 5-6m in 2006. Each project had more than 1200 corals transplanted onto it – coral growth was healthy and marine-life became abundant on the structures.
Then two major hurricanes hit the island. Hurricane Ike, the most powerful on record to hit Grand Turk, followed very quickly in the wake of Hanna.
It caused a third of the corals to be lost, and some of the cables to be displaced, but in general the arti?cial reef survived better than the natural reef.

SWIMMING AROUND
the beautiful and photogenic structures in Pemuteran, I not only saw surreal-looking biorock, but ones shaped like a manta, a nudibranch, a snail, a seahorse and a dolphin.
One of the newest structures was a large wave with a sperm whale riding it, installed only a few weeks earlier. Already a large grouper had found a home in the barrel of the wave.
A large school of snapper floated above a structure in the shape of a temple roof, set below a swim platform located above the centre of the dive-site for snorkellers to enjoy.
I snorkelled and dived this site many times over the week I stayed in Pemuteran. Each time I discovered something new, or found a different angle from which to look at the structures.
Seeing new life growing so encouragingly and strongly made me revel in the beauty and magni?cence of the undersea world.

For more on biorock and the locations of its projects, go to www.biorock.net