Maldives Biorock Figures compressed

January 31, 2022

GCRA White Paper


Past results & future applications

Thomas J. F. Goreau, PhD

President, Global Coral Reef Alliance


The Maldivian way of life for more than four thousand years is under imminent peril from global climate change. Biorock® technology, an open-source technology invented in Jamaica and developed in the Maldives nearly a quarter century ago, can save the archipelago and create a sustainable blue economy. Biorock technology uses Safe Extremely Low Voltage (SELV) electrical currents, which can be powered by solar and ocean energy, to grow solid limestone structures of any size or shape in the sea, which grow upwards to match sea level rise. The photograph gallery of this report shows the results of the original Biorock projects in the Maldives in the 1990s, which saved a reef from bleaching and quickly grew back a severely eroded beach. In 1998 Biorock structures were proven the most cost-effective solutions for most Maldivian marine management problems, including shore protection against rising sea level, preserving coral reefs from bleaching and global warming, regenerating marine ecosystems and fisheries, sustainable mariculture, and producing harder, cheaper, carbon-negative building materials. Biorock technology provides the best and lowest cost tool to create permanent custom-designed reef solutions, powered by sun and sea, to grow the Maldives up and out of the climate emergency. A Biorock Maldives training workshop is proposed to develop Biorock technology’s potential benefits to save the archipelago and supercharge the Maldivian Blue Economy is urgently needed: another El Niño is starting, and while still too soon to make predictions, may be worse than 1998 and 2016.  


The Maldives is one of the lowest countries in the world and most vulnerable to global sea level rise. For more than 4,000 years Maldivians mined coral for building stones, cemented together with quicklime made by burning corals. By the 1980s coral reefs around the capital city, Male, had been effectively mined out, destroying natural shore protection, allowing high tides and swell from remote storms to flood the island and cause cholera outbreaks. An emergency Disaster Prevention project funded by the Japan International Cooperation Agency built a sea wall of concrete tetrapods shipped from Japan all around Male Island at a cost of around $13,000 per meter, which prevented the disastrous flooding that affected nearly 200 unprotected inhabited islands during the December 26 2004 Asian Tsunami. Coastal armoring has greatly accelerated in recent years (Duvat & Magnan, 2019) and affected water flow patterns and sedimentation (Rasheed et al., 2021).

Maldivian islands have clear long-term erosion problems, superimposed on annual shifting of sand between east and west of each island caused by changing seasonal Monsoon wind directions. Most Maldivian resorts built stone sea walls to prevent beach erosion, built from mined corals, killing living reefs for temporary protection that failed after storm waves shifted dead coral rubble piles. To stabilize dead coral sea walls many resorts covered them with gabion wire mesh, but this rusted after around a year, followed by collapse. Resorts then shifted to more expensive plastic-coated mesh, but the plastic coating soon cracked from ultraviolet light, and rusting and collapse was only slightly further delayed.  


In the early 1990s the University of Newcastle Upon Tyne built a vast artificial reef complex near Male from 360 tons of concrete shipped from England, mostly superhighway concrete bridge overpasses, dumped on 4 hectares of barren mined out reef, broke off corals from living reefs, and cemented them to the concrete. It was claimed the largest and most successful reef restoration project in history (Clark & Edwards, 1994)), as well as the most expensive. When I filmed the project in 1997 all the originally transplanted corals had died but I found a handful of baby corals, mostly of weedy species of Pocillopora, had settled on the undersides of the concrete slabs. It looked like a parking lot, and remains a wasteland, with only a handful of corals on 360 tons of concrete.  Coral mortality was caused by poor water quality at the site (Goreau, 1998), near Male sewage outfalls, as the corals died well before the 1998 bleaching event.

Ihuru Resort, owned by Ahmed Mujthaba, established a coral regeneration program headed by former Maldives Director of Agriculture, Azeez Hakeem, who planted gardens of coral fragments cemented or glued to concrete blocks arranged around the resort. Until the 1998 bleaching event, Azeez had 100% coral survival, and was the most successful coral gardener in the world, while Newcastle had nearly 100% mortality. The difference was due to the Newcastle site being next to the Male underwater sewage outfalls, while Ihuru is much further away (Goreau, 1998; DeGeorges et al., 2010). Nevertheless, coral fragmentation onto exotic substrates continues apace in the Maldives, mostly by resorts, with few long-term results because most may have died in the 2016 bleaching event.

Maizan Hassan Maniku, founder and Director of the Marine Research Centre of the Maldives Government Ministry of Fisheries searched for alternatives to concrete, found the Biorock work of Wolf Hilbertz and Tom Goreau of the Global Coral Reef Alliance in Jamaica, growing coral reefs and building materials in the sea by electrolysis, and invited us to come and explore Maldivian applications.


Biorock projects began at Ihuru Island Resort in North Male Atoll in 1996. Wolf designed and built the first Ihuru Biorock structure, a large conical structure called “The Barnacle”, on the outer slope of the island. The Barnacle quickly showed extraordinary coral growth and fish populations in comparison with healthy coral reefs around it, and with the transplanted coral gardens, which were both filmed as controls to compare coral growth rates with Biorock corals. Following this, another large spectacular Biorock reef, “The Lotus”, was built on nearby Vabbinfaru Island.

Ahmed Mujthaba told us that the pier used to bring guests to the resort had steel pilings that were rusting, about to collapse and would soon need to be torn out and replaced. Wolf Hilbertz explained that we could use Biorock technology to stop all rusting on the underwater part of the pilings and grow limestone rock and coral over them. We did so, and it worked.

Ahmed Mujthaba thought dead rock breakwaters used by most resorts were both unattractive and ineffective, so the resort invested in pumping sand into mesh bags to line the shores, which were more comfortable for tourists to walk and lie on that rock walls. These lasted until the first big storm, when the sand was lost and the shore littered with plastic fragments, and were also extremely expensive to re-do every six months when the winds reversed. They proved incapable of preventing erosion. The photographs show the beach on the south side of Ihuru Resort just before the project began. The beach had washed away completely, a wall of sandbags was propping up a small sand cliff behind which trees were collapsing into the sea, and buildings were about to follow them.

With a team of welders from Male, German volunteer architecture students, and the resort staff, Wolf Hilbertz built a 50 meter long Biorock reef directly in front of the severely eroded beach. The structure used 2270 meters of 12 mm rebar, 350 meters of recycled 6 mm iron wire, and 6kg of 2 mm binding wire. Welded modules were placed on bare rock, connected together in the water, and charged via three chargers with electricity from the resort’s power system. The entire structure used about 3-4 kilowatts of electricity, or a couple of air conditioners worth. Since the resort had hundreds of air conditioners, the reef project used only a very small fraction of the resort power, less than the beach lighting. The Biorock reef was called “The Necklace” because it was intended to be only the first stage of growing a reef to surround the entire island with natural beaches and make expensive sand bag pumping unnecessary. See photo gallery of GCRA’s Maldives Biorock Report (please click on the picture to see captions and advance slides).

In 1997 loose corals transplanted on top of the Necklace by Azeez Hakeem grew at spectacular rates. The structure cemented itself solidly to the bottom with limestone. Sand piled up underneath the open framework and on the beach, which grew to cover all the previously eroded beach and grew towards the Biorock reef protecting it. The photograph shows the new sand beach that grew by itself, in front of the largest building on the island, the ocean restaurant. At start of the project this building had a wall of sand bags in front to prevent collapse. Ahmed Mujthaba had told us they would have to tear down the building because it would soon fall into the sea. Biorock technology rapidly succeeded where everything they had tried to do to stop the erosion had failed!

The next year, 1998, the Maldives was hit with the highest sea water temperatures and the most catastrophic coral bleaching recorded (Goreau et al., 2000). I had been filming transects of corals all around Ihuru island, and on remote control reefs, including slope reefs, reefs on shallow flats, and Azeez Hakeem’s transplanted coral gardens. My videos showed the natural reefs were devastated, coral mortality was around 99% on the shallow reef flats all around Ihuru, and around 95% on deeper island slopes. Every single one of Azeez Hakeem’s transplanted corals died. Yet most of the corals on the Biorock reef survived, even though water temperatures in the Necklace reached up to 35 degrees Celsius. Azeez Hakeem estimated coral survival on the slope was around 80% on Biorock compared to around 5% on natural reefs, and that around 50% of the corals on top of the Necklace survived, while in surrounding reef flats my videos showed only around 1% survival, a handful of large Porites heads (Goreau et al., 2000; Goreau & Hilbertz, 2005; Azeez Hakeem et al., 2010; Goreau et al. 2012):

Many corals died on top, but the shaded lower sides survived and grew back over dead areas from beneath. After the mass bleaching mortality reef fish from dead reefs migrated into the Biorock reef, and for around a decade afterwards tourists would pay to come from other resorts to swim at Ihuru, because it was the only resort that had a natural beach with a live reef full of spectacular coral and fishes right in front of it. Other resorts had rock walls, and their House Reefs had died and become dead rubble. The 1998 Bleaching event wiped out most reproductive coral populations in the Maldives, so there was very little recovery for years until new coral larvae could be transported from Indonesia by seasonal currents, and grew to reproductive age. 

In the 1998 bleaching event all the non-Biorock coral transplants at Ihuru died, they could not stand the high temperatures, while corals growing on Biorock near them mostly survived. In 1998 it was shown in the Maldives that Biorock was the only method that protected corals from severe bleaching mortality, while all other fragmentation and attachment methods failed. Yet these lessons were neglected, and the old methods are still being used in “mitigation” projects for dredging impacts, in places where corals will die from pollution or high temperatures, sooner or later.

Soon after the bleaching event the resort was sold to a foreign operator, who immediately shut off power to the projects, and would not allow us to monitor, document, maintain or repair the projects. They already had the spectacular beach and reef we had grown for them, so they preferred to reduce their electric bill by a tiny amount rather than maintain their reef. Photos taken in 2009 by Dr. Norman Quinn, 11 years after bleaching and 5 years after the tsunami, and in 2012 by Azeez Hakeem, 15 years after installation, are in the photo gallery. Despite being without power for all but the first 2-3 years, the Biorock reef remained spectacular. While the Biorock reef looked extremely healthy, the initial advantages of more rapid growth and higher resilience to bleaching were lost (Azeez Hakeem et al., 2010), along with electrical protection from bleaching. The Maldives was exceptionally lucky no severe bleaching happened for 18 years, until 2016. In 2016 the corals the Biorock Arks had saved from bleaching in 1998 were no longer protected by the life-saving electrical current.

The 2004 Asian tsunami swept over the island and carried Azeez Hakeem out to sea. Luckily, he managed to swim back, and there was no damage to the Biorock reef structures, the corals growing on them, or the beach (see photos below). The new owners refused our requests to document and maintain the projects. They set up a “scientific research centre” for tourists to feed fishes addicted to junk food, pet sting rays, and release baby turtles whose eggs were collected from other islands, but no systematic effort was made to document the unique Biorock coral reef and beach regeneration projects at Ihuru, shown in the photo gallery accompanying this report. Nearly 25 years of crucial importance to the Maldives were lost for saving the corals from global warming and beaches from global sea level rise, using methods developed in the Maldives.


The 1998 Maldives results conclusively showed that Biorock technology is the best, most cost-effective solution for saving corals and reef biodiversity from global warming, for shore protection that grows with sea level rise and will not be overtopped like concrete and rocks, and sustainable mariculture. Many of these applications were first proven in the Maldives in the 1990s, but were ignored because foreign funding agencies will pay for imported concrete and dredgers, but will not fund coral reef and island regeneration methods invented in Jamaica and developed in the Maldives! Because the technology came from Small Island Developing States, rich countries wouldn’t fund Biorock because they couldn’t claim it as “technology transfer” aid.

Biorock is an essential tool to Climate-Proof Maldivian coastlines from sea level rise and global warming by growing back dying reefs and eroding beaches, regenerating biodiversity, and creating lush attractions for ecotourism (Goreau, 1998). Biorock reefs cost a tiny fraction of concrete and rock walls, which provide no environmental benefits except holding back sand until the wall inevitably collapses from the scour and erosion that they cause by reflecting waves. Biorock reefs accumulate sand under and around them instead (Wells et al, 2010). Biorock reefs can be built in any size or shape, and added on or subtracted from if needed. Biorock reefs could be powered by floating solar panels, waves, or tidal currents. Biorock also greatly increases growth of seagrasses, saltmarsh, and mangroves, regenerating natural coastal protection of living shorelines and juvenile fish habitat.

Biorock technology has many additional applications that have never been tested in the Maldives. Biorock allows whole ecosystem mariculture of biodiverse food chains that grow their own food without need to add commercial feeds (Goreau, 2018). Very complex fish populations rapidly built up on Maldivian Biorock reefs, some species hiding inside structures in the day time and feeding at night, while others feed in the daytime and sleep in Biorock at night. Which species crowd into Biorock reefs depends on the size and shape of the holes, and how many of them depends on the total number of suitable holes available. Different species dominate adjacent structures of different shapes, which can be built specific to needs of different species, for example with larger holes for groupers and smaller ones for their prey populations to shelter in. Oysters and giant clams grow at accelerated rates on Biorock. Habitat for species that are limited by lack of suitable holes, such as octopus and lobsters, can be made in any number desired. Biorock reefs in Mexico and Jamaica had dozens to hundreds of lobsters in a few square meters. Biorock nurseries have been successfully used to grow millions of sea cucumbers in Micronesian atolls (Hagberg,

Biorock can also be used to grow upside-down floating reefs, growing from the surface, creating reefs over deep water where there is no light for corals on the bottom. Floating Biorock reefs in the Bahamas grew a lush marine community that filtered polluted canal waters. Biorock floating reefs and islands can be moored to Biorock anchor mooring reefs on the sea floor, which regenerate bottom fish and shellfish populations. Floating Biorock reefs provide superior Fish Aggregation Devices (FADs) that both provide shade that tunas like to aggregate under, and also grow the smaller fishes they eat. Such devices could be placed in Maldivian coastal waters to retain and maintain Maldivian tuna populations that are intensively overfished by foreign fishing fleets waiting with long lines and drift nets just outside the Maldives Exclusive Economic Zone to seize all tuna leaving Maldivian waters.

Another major application is growing limestone building materials in the sea to replace threatened corals and expensive and polluting imported cement. Construction materials more than 3 times harder than concrete can be grown from local renewable energy from sun and sea for less than costs of importing cement. Each ton of Portland Cement releases a ton of CO2, but Biorock construction materials grown from local sea and sun are carbon sinks. Sand-producing coralline algae are greatly stimulated by Biorock reefs, growing new sand as well as trapping old sand. By replacing expensive global-warming Portland Cement with carbon negative material produced from Maldivian natural resources, Biorock artificial islands can be grown that will match sea level rise, while surrounding Biorock reefs protect them from waves, feed them, and grow new sand for land fill.

The Maldives can use Biorock Technology as a critical island-saving tool against global sea level rise, a life-saving tool for coral reef biodiversity preservation against global warming, for regenerating fisheries, and for producing carbon negative building material. The Maldives could literally grow its way up and out of the climate emergency with Biorock technology, building up by removing CO2 from the atmosphere while sea level rises. Biorock integrated into the national problem-solving toolkit can do the most to protect ALL Maldives investments and natural capital from the unprecedented threats climate change will cause the rest of this century. Biorock can grow the backbone of a resilient adaptive blue economy for the Maldives.


In 1996 the Global Coral Reef Alliance proposed to Maizan Hassan Maniku, founder and Director of the Marine Research Centre of the Maldives Government Ministry of Fisheries, to hold a Maldives Biorock Training Workshop. Unfortunately, this was prevented because Maniku had a heart attack soon after, but GCRA still remains ready. Wolf Hilbertz and I developed Biorock technology in the Maldives because we thought it the country that could best benefit from Biorock. Our greatest hopes were to see Biorock save Maldivian islands and marine resources. Wolf is long dead, I have little more time to lose, sea levels are rising faster, and an El Niño is coming! The best time to hold the Biorock Maldives Training Workshop was in 1996, the next best is in 2022.

PHASE 1: Biorock Maldives Training Program & Pilot Project

The Global Coral Reef Alliance, inventors and developers of Biorock technology, offers to teach a Maldivian Biorock Training Workshop to train a core local team in theory and hands-on practice of Biorock design, construction, installation, maintenance, monitoring, and repair. Technical consultancy will be provided by Blue Regeneration (owners of the Biorock® trademark), and Biorock Indonesia will assist training of community-managed, youth, and public education aspects. The workshop will be held at Hulhumale, and the pilot project will build a 5 kilometer Biorock shore protection reef along the East Coast of Hulhumale. An initial estimate is that around 20-40 million USD will be needed for inshore reefs, offshore reefs, and tuna habitat in deeper waters along the shore, but a detailed site assessment is needed before designs can be prepared and costed. Biorock training is the most urgently needed first step and should start as soon as possible! Erosion never sleeps, another tsunami could happen any time, an El Niño event is starting, Maldives could lose a lot of corals this year or next! Biorock Coral Arks are urgently needed to save corals from mitigation projects that will die from high temperature or bad water quality if transplanted onto concrete.


The cost/benefit analysis of Phase I results will be used to train Maldivians in the full range of Biorock technology applications, to develop strategic projects incorporating Biorock coastal protection and sustainable mariculture where needed to save islands, manage natural resources, and generate a sustainable carbon-negative blue economy. There are no limits to what can be achieved if the will, funding, and training are ready.


The author gratefully thanks Dr. Maizan Hassan Maniku, Ahmed Mujthaba, Abdul Azeez Abdul Hakeem, Dr. Norman Quinn, Wolf Hilbertz, student volunteers Frank Gutzeit and Ari Spenhof, the staff of Ihuru Resort, and all who helped make this work possible.


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PDF Archive of 111 Biorock Maldives results in photographs with captions