Coral Reef Restoration in Pemuteran: the Biorock® Project (Full ArticleAuthor: Francesco Ricciardi
One of the biggest issues in tropical countries is the deterioration of coastal coral reefs due to many factors, such as coastal erosion, illegal dynamite and cyanide fishing, chemical pollution, and other threats. Over the past 20 years, these combined factors have destroyed many coral reefs and coral areas around tropical countries worldwide.
Healthy coral reefs are vital to the survival of not only aquatic creatures, but coastal populations as well. They provide food, serve as nurseries for many species of commercially important fish, and can be a huge source of income via the tourism industry. For people living in coastal villages in developing countries, scuba diving, snorkeling, and other water sports can be far more valuable than fishing.
Unfortunately, even if prohibited by law, dynamite fishing is still practiced in many parts of the Western Indo-Pacific archipelago, and a large part of the coral reefs around the Philippines, Indonesia, and Malaysia have been destroyed, especially in remote areas where patrolling and sea surveillance are very difficult.
Underwater bombs are normally prepared using a bottle and some chemicals like powdered potassium and pebbles or ammonium nitrate (a common fertilizer) mixed with kerosene. Once released in the water (but sometimes even before, causing serious injuries to the fishermen) the bomb explodes. These explosions rupture the swim bladders of surrounding fish, which are easily collected later.
Due to the nature of the explosion, this fishing method affects more than just the target animals and irreversibly damages the fragile coral reef ecosystem. Wonderful coral gardens that were teeming with life are reduced to deserted areas of coral rubble. Even worse, they become unsafe regions for fish to mate, and they create adverse conditions for new coral larvae settlement, meaning these areas will be unable to recover for a very long time, if at all.
Saving the Reef
Some years ago, two scientists (Professor Wolf H. Hilbertz, who passed away in 2007, and Dr. Thomas Goreau, who is at the moment President of the Coral Reef Alliance) discovered a technology called electrical mineral accretion (which is known as Biorock®). Basically, a low-voltage current in seawater causes dissolved minerals to crystallize and form structures similar to limestone, on which coral larvae can settle and grow. Moreover, it seems that this low voltage can stimulate carbonate deposition by corals, increasing their growth rate.
A new Biorock® structure starts with the positioning of a submerged anode (negative pole), normally an electrically conductive frame made from wire mesh. The anode is connected to a low-voltage electrical current that is not harmful to fish or other sea life. A metallic submerged structure acts as the cathode (positive pole), starting an electrolytic chemical reaction that causes the precipitation of minerals naturally present in seawater, such as calcium carbonate and magnesium hydroxide, which are deposited on the structure’s surface. After only a few days, a whitish layer of minerals already covers the structure.
When the first layer of limestone has been deposited, some so-called baby corals (living fragments of broken corals coming from other areas) are implanted on the structure, where the current stimulates their growth. It has been calculated that they can increase their growth rate to almost five times that of a normal coral. The limestone deposit also helps the reef recover from other environmental stresses, such as fractures, high temperatures, waves, or excessive sedimentation.
This technology has been further developed and adapted for use in coastal environments, where it’s possible to use photovoltaic generators, or a device using waves or wind generators, to create a self-sustaining system using green energy to stimulate the coral recovery. One of the most awesome examples of this technology’s success is easily observable in few feet of water in front of the village of Pemuteran, North Bali.
The Pemuteran Biorock Project
In Pemuteran, only a few years after the first structure was installed, the results are amazing to behold. The corals grow quickly and are healthy, and fish life is abundant. Invertebrates like crabs, sea slugs, and shrimp are abundant and now occupy every shelter inside the Biorock. Some local dive guides and instructors are working hard to get new funds from tourists and create new structures.
Since the base of the Biorock can be placed in whatever shape you choose, it can be an artistic way of regrowing corals. Sculptures such as metallic crabs, nudibranchs, a sea goddess, igloos, and even old bicycles have been sunk onto the reef and are now the basis of new coral reef formations.
Komang Astika, diving instructor and native of Pemuteran, is one of the members who have been with the Karang Lestari Foundation since the beginning. “I started volunteering in 2000, when I was still very young, because I believe that all our community depends on the health of the coral reefs. Since 2007 I have become a full member of the Biorock Project,” he said.
The Karang Lestari Foundation
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