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Wednesday, Sept. 27, 2000

Cultivating coral gardens

Man-made reefs prove to be self-rejuvenating


By ROB GILHOOLY
Staff writer

IHURU, Maldives -- A sudden change in the weather sends staff at the resort on Ihuru Island grappling for the groins. Jetty-like piles of sand-bags that jut out from various parts of the island, these "groins" help lessen the effect of destructive tides. For the time being at least, they are Ihuru's lifeline.

Scientists believe many Maldivian islands like Ihuru (above, foreground) could be submerged within 40 years.

Like many of the 1,200 islands that make up the Maldives, Ihuru can lose several meters off its shoreline in one blustery day -- life-threatening for an island not much bigger than a soccer field.

Azeez Hakeem, an official at Ihuru's resort and a self-taught marine biologist, patrols the island twice a day to check sand movement, which is compensated for by a system of pipes allowing sand to be pumped to an affected area. "It's a constant fight against nature to protect nature," he said.

The reason this artificial line of defense is needed is the ongoing, gradual demise of a natural one -- the coral reefs on which the island, and indeed the entire small Indian Ocean nation, are founded.

Global warming and climatic disasters like El Nino are cited as two major factors in the destruction of the Maldives' coral reefs -- its natural protective barrier. The result has been widespread beach and land erosion, as well as the intrusion of salt water into aquifers.

Experts estimate that the El Nino of 1998 adversely affected nearly all the Maldives' coral. "Status of Coral Reefs of the World," a report released by the Global Coral Reef Monitoring Network regarding the 1998 disaster, rated bleaching in the Maldives as "catastrophic," saying severe bleaching of around 95 percent of shallow corals had occurred.

Beneath the seas, the Maldives is one of the most mountainous places on Earth, but above water it is the flattest nation on the planet. Some experts predict that, if erosion continues at the present rate, many islands will have joined the peaks and valleys below within 40 years.

Staff on Ihuru island are determined not to go under without a fight. Azeez says the only chance of survival for small, low-lying islands like Ihuru -- whose reef attracts thousands of tourists every year -- is to restore the coral. Ihuru has therefore invested in a unique and ecologically sound project that it believes could help stem the tide and save the Maldives -- and perhaps other low-lying island nations worldwide.

An unusual "crustacean" looms on the seabed just off Ihuru. Some 4 meters in height, the "Ihuru Barnacle" has become an underwater magnet for species of reef fish whose numbers had been greatly reduced by the 1998 disaster. It is, however, entirely man-made.

The barnacle and several other structures installed by marine scientists between 1996 and 1999 are assisting in the recovery of coral reefs while at the same time functioning as new reefs and breakwaters themselves.

Azeez Hakeem (above) displays a model of the "Ihuru Barnacle," the 4-meter-high, electrically charged coral-growing structure that he "weeds" and plants daily (below).

The cone-shaped structure is made from construction bars and carries a low-voltage electric current, generated by a solar panel.

An electrolytic reaction at the negatively charged cathode terminal -- attached to the structure itself -- makes the water around it more alkaline, causing calcium carbonate particles to attach to the structure. Over time, layer upon layer of limestone coats the structure, providing the perfect base for coral, which, according to Azeez, thrives on clean limestone.

Many baby corals seek out the structure naturally; others are transplanted onto it from reefs that survived El Nino, Azeez said.

The technology was developed by Bangkok-based German architect Wolf Hilbertz more than 25 years ago, as a way of creating alternative building materials. In 1989, he joined forces with Dr. Tom Goreau of the Global Coral Reef Alliance, a U.S.-based nonprofit organization for the protection and sustainable management of coral reefs, to apply the technology to the construction of artificial reefs.

Subsequent experiments in the Maldives, Jamaica and other countries have been fruitful, Goreau said.

"These are growing life-support systems," he explained. "The technology is . . . the only method that grows limestone structures in the sea, providing the natural settling substrate, and allowing corals to grow their limestone skeleton at greatly accelerated rates."

The use of artificial reefs is not a new phenomenon. They have been used for attracting fish in China and Japan, for example, for centuries.

The reefs originated from fishermen's knowledge that fish form schools under and around floating tree trunks. Early examples were mostly made from bamboo, but these have been reproduced using a variety of other materials, such as rubber tires, concrete blocks, and even abandoned cars, ships and planes -- often providing a welcome excuse to dispose of unwanted junk.

But these were all intended to serve a reef-like function, not to actually become one, said Goreau.

"Fish will hide behind any structure, especially if it is placed in an area without shelter, but such structures do not turn into coral reefs in any biological sense," he said.

"Corals are almost all extremely fussy about settling only on clean limestone, and avoid almost all exotic materials," he added.

What's more, it has been shown that while the other materials corrode and fall apart with age, the mineral-accretion structures become more massive and stronger.

Hilbertz believes the natural self-rejuvenation of coral reefs after phenomena like El Nino could take decades -- "if the conditions were right."

"But I doubt we'll have the necessary paraphysical conditions again. Global warming continues, pollution is increasing. And there's no doubt 1998 will repeat itself. The only question is when?" Hilbertz said.

Coral-reef management is the only option left, Hilbertz added. "Mineral accretion is a management tool. These structures are coral nurseries where heat-resistant coral species are being grown."

Managing Ihuru's reef is a time-consuming business. In addition to grafting corals onto the structures from reefs that resisted the rise in water temperature triggered by El Nino, Azeez also dives to the structures daily to remove coral-disrupters, such as snails and other unwanted organisms.

He likens the process to gardening: "You have to control the weeds and bugs while bringing in cuttings to assist growth. It requires constant care and attention, just like a garden."

He is reaping the rewards. Mineral-accretion growth on Ihuru's structures has been as high as 20 cm per year, while coral grows as much as five times faster than normal, Azeez said. The structures are already absorbing a significant amount of wave energy, he added.

Some of the structures at Ihuru were put into place before 1998, so Goreau and Hilbertz have been able to observe how the cultured corals fared as sea temperatures reached 3 C above the average. A rise of just 1 C can cause severe bleaching.

Goreau and his team observed that while many corals on reefs surrounding the barnacle were bleached in 1998, most of those that were attached to the man-made structures survived. Mineral accretion, he said, allowed them to survive the starvation and stress that accounted for most bleached coral.

Furthermore, species of tropical fish that depend on coral either for food or habitat are seen today almost entirely among the mineral-accretion structures, particularly the barnacle, which has become a major "cleaning" station for rare marine fish species that also use it to protect themselves from predators, Azeez explained.

"Another consequence of bleaching is that such fish lose a natural form of camouflage and protection," Azeez said. "Now these fish are returning, having found somewhere that gives them shelter. It's the best place to observe some rarer species."

Goreau's organization currently has two other similar artificial-reef projects under way at Isla Mujeres, Mexico, and Pemuteran, northwest Bali, Indonesia, and a coral nursery on Phuket Island, Thailand.

All are producing high rates of coral growth, according to Goreau.

Yet appeals to put the technology to wider use have found little support from Maldivian officials, who so far have not even made the short boat journey to Ihuru from the capital, Male, to see it for themselves, said Goreau.

Goreau, Hilbertz and Azeez -- himself a former minister in the Maldivian government -- have sent reports to the government detailing the merits and potential of the mineral accretion system, but with little success.

"This is a real tragedy, as the best technology in the world for solving their shore protection problems is visible at their very doorstep," said Goreau. "We can only hope that they choose to make up their minds while there is still time to protect the country from the double impact of global warming and global sea level rise."

Hilbertz said he finds the official attitude "baffling," given that the Maldives' biggest foreign-income source is tourism: Diving and snorkeling enthusiasts from around the world swarm here to explore the nation's rich marine life.

On a global level, however, the lack of awareness of the plight of the world's coral reefs is not a complete surprise, Hilbertz added.

"Coral is not so immediately visible and not seen as a commodity, like forests," he said. "If in '98 (an equivalent percentage) of our forests had been eliminated, we would have had an outcry and a stream of public measures. But coral is not understood. It's a simple case of negligence."

In addition to efforts to rehabilitate reefs in the Maldives, Hilbertz has also tried to grow alternative building materials using the mineral-accretion technology.

This, he hopes will provide local developers with an alternative to mining out reefs -- a common practice in some low-lying, resource-poor island nations.

Coral rock has been traditionally used as the main source of building material in the Maldives, and a recent estimate is that up to 1 million cubic meters are mined annually, according to the Australian Institute of Marine Science.

Experiments by Hilbertz have shown that it is possible to grow coral into any size and shape. "It is possible to create a never-ending coral quarry under the sea that replenishes itself automatically via mineral accretion," Hilbertz said. "Ultimately, you can make a whole island, providing you have the solar needs."

This, he says, is ideal for island nations such as the Maldives, yet many are too caught up in the methods of the Western world.

"It's very hard to change the perceptions of these governments if what you're promoting hasn't been tried in the West," Hilbertz said. Unfortunately, "temperature requirements mean this technique is best suited to the tropics, not the West."

A frustrated Azeez says he has tried to encourage other islands to implement the technology. "Frankly, they don't care. Their answer is to cut up the reefs and build a wall. They don't seem to realize this is their future, that time is running out."

Where corals come from The Earth's coral reefs cover just 750,000 sq. km, roughly twice the land area of Japan and less than 0.3 percent of the ocean floor. However, the shallow, near-shore zones they occupy support over a quarter of all marine animals and plants.

Coral is basically made up of marine organisms, called polyps, that process calcium from seawater, which they then deposit as tiny limestone skeletons. A coral reef is the rocky accumulation of millions of these animals and their exoskeletons.

Living inside polyps are microscopic algae that transform sunlight into oxygen, thus keeping corals alive. But this symbiotic relationship can turn deadly if the algae are fed too many nutrients and become overnourished.

This can happen if the surrounding oceans become polluted with chemicals from raw sewage or fertilizers, for example. In this event, the algae overgrow and eventually choke the corals.

It is no coincidence that coral thrives in the relatively nutrient-poor waters of the tropical and subtropical oceans.

Another of the many abuses to which corals are subjected is bleaching, which is triggered by even the slightest rise in water temperature. When water temperatures increase, corals reject the algae that feed off them. As coral depends on those algae for essential nutrients, it effectively starves. It is algae that give coral their stunning array of colors, so their desertion leaves the coral white, or "bleached."

There are three types of coral reefs: fringing corals, barrier reefs and atolls. Spread out over 750 km, the 1,200 coral islands of the Maldives are nestled on the rims of 26 atolls (the word "atoll" actually comes from the Maldivian "atolu.")

In a process that takes hundreds of thousands of years, atolls are formed by coral buildup on the shores of a volcano. As the volcano sinks below the water, the coral continues to grow upward, forming a barrier reef that is separated from the sinking land mass by a lagoon. With time, the volcano becomes completely submerged, and coral growth is sufficient to form a ring-shaped atoll, parts of which emerge above the sea to form coral islands. (R.G.)



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