In Indonesia, ecologists have created ‘biological rocks’ a.k.a. ‘biorocks’ on the ocean floor using an ingeniously simple technology.
Beneath the clear water lies a couple of motorbikes, sitting atop a big steel structure in the shape of a speedbump. It is covered in coral, and tropical fish dart under the handlebars and between the spokes of the wheels.
The structure isn’t an art installation because their frames tingle with electrical currents, which helps them create a rocky coating – which in turn becomes a nursery for coral reefs that have been damaged by human activity.
These electrically charged shapes are in Gili Trawangan, one of three small islands northwest of Lombok in the Indonesian archipelago. A tourism industry has sprung up here in record time. With it, a small group of expat environmental activists have clubbed together to create the steel structures submerged in the nearby waters, and shown how a new technology may help this developing nation safeguard some of its natural wonders.
I was really quite amazed and surprised to see the results of the technology,” says Delphine Robbe, the manager of Gili Eco Trust.
Originally from France, Robbe moved to the island as a dive instructor in the early 2000s. She started the biorock project a decade ago, funding it originally through her own salary. There are now 111 of them across the three islands, each costing around £1,500 ($2,270)
A low-voltage direct current is run through the steel. This electricity interacts with the minerals in the seawater and causes solid limestone to grow on the structure. It draws on the principles of electrolysis, where the electric current causes a chemical reaction to occur which wouldn’t have otherwise.
Eventually, the limestone will solidify.
It’s the same thing that makes up [marine] skeletons. And it’s a perfect breeding ground for aquatic life. It’s speeding up the normal reaction of coral growth. Corals on the biorocks survive more than any other,” says Robbe.
When divers see injured coral, they move it to one of these structures to rehabilitate. The coral heals some 20 times faster, and has up to 50 times more chance of survival. The rehabilitated coral can often be astoundingly brilliant in colour and densely branched. Once healed, it is returned to the open sea.
Just observing the reef and hoping it will recover is pointless – it doesn’t work,” says Robbe.
She says there are coral rubbles lying on the seabed that, with strong storms and waves, that are constantly being shifted about, making their regeneration impossible.
The behaviour of locals and tourists don’t help either. The use of heavy nets and even dynamite by fishermen, dragging anchors, and divers and tourists touching or walking on the reef all cause damage. “These are all forbidden in the Indonesian lawbook but there’s no control,” she says.
Hence, the biorocks – shaped like giant steel manta rays, pyramids, planes, dolphins, whale sharks, lizards and turtles – are helping to stave off these adverse effects.
And it’s not just coral that improves: the biorocks have helped the fish populations as well, particularly lobsters and juvenile fish who shelter in the structures.
Now we have more biodiversity and the water quality is better,” Robbe says.
They have also helped turn the tide when it comes to severely eroding beaches. Slowing the onslaught of fast waves, biorocks lead sand to be deposited, rather than eroded, at the shoreline. This has seen certain parts of the beach grow some 15 metres in a few years and they’ve proven themselves resistant to damage from natural disasters, such as the Asian Tsunami of 2004, as their open frameworks allow large waves to pass through.
While there is no limit to the size or shape of the structures – they could be hundreds of miles long if funding allowed – there is a limit when it comes to powering them. Because in a developing country like Indonesia, electricity means oil. It’s a vicious circle environmentally.
Thus, the team has experimented with powering biorocks using solar energy from a solar panel on a barge above the structure. The only problem? The panels are often stolen. So what now?