What Are Bio-Rocks? – Gili Eco Trust

Bio-rocks is a relatively new technology that allows corals to regrow into coral reefs. These structures are an essential part of the projects that Gili Eco Trust invest in to rebuild coral reefs in the Gili islands that have been damaged by boats dropping anchors and fishing practices.

Here is a diagram of a bio rock:

Bio-rocks are man-made structures that through electric currents and electro-accumulation of minerals dissolved in seawater, stimulate the growth of corals. There are 127 biocoks in gili making it the second-largest program in the world.

Gili has credited their bio rocks to “Marine scientist Wolf Hilbertz in 1974 was researching seashells and coral to find out how they grow. He found that by passing an electrical current through seawater, the salty water electolyzes causing calcium carbonate to combine with magnesium. Chloride and hydroxyl ions slowly form on the cathode and this eventually coats the electrode with a material almost as strong as concrete. Over time this material hardens further, growing and becoming stronger as long as the current flows as much as 5cm per year. It can even heal itself if it were to be damaged and due to it’s high levels of dissolved oxygen it is particularly attractive to marine organisms The superfood for our coral reefs! ”

Students can come to Gili to work on the project and is mainly aimed at gap year students, people on career breaks and anyone interested in more than just a normal vacation. Volunteers can come along to the island and help out on new Bio Rock projects, work on maintaining existing ones or even sinking their very own brand new Bio Rock. Other activities include how to create and maintain a coral garden, learn about environmental threats and coral biology, and how to survey coral gardens.