Providing both food and shelter for marine life, coral is a vital ecosystem

But while the situation is dire, an ingenious technique for regenerating coral -- by using electricity to suck stone out of water -- could help. 

 

Coral reefs -- like these off Zanzibar -- are dying from the heat

Called mineral accretion, it was first designed by architect Wolf Hilbertz as a way of creating new construction materials. But it was soon transformed into a life-saving system for coral reefs by a scientist intent on stopping coral devastation before it's too late. 

"The method creates conditions that make coral grow at least four times as fast," says Dr. Thomas Goreau, president of the Global Coral Reef Alliance and co-creator of the mineral accretion method. "It is the only technology in the world that can grow corals and build effective erosion barriers for coastlines." 

 

Dead coral becomes covered by "bad" algae -- that squeeze out new coral

To understand why mineral accretion works -- and why it's vital to coral survival -- it's important to understand what coral is, and why it is threatened. 

Coral reefs are created by tiny organisms -- coral polyps -- that produce calcium carbonate (limestone) structures as their exoskeleton. In a beautifully symbiotic relationship, the polyps depend on microscopic algae that live on the reefs they build, for nutrients. The result is a living structure that provides both food and shelter to fish and invertebrates in shallow tropical waters. They also protect land from erosion, and when parts of the reef break off and wash up on land, it produces the white sand beaches people love. 

But when ocean temperatures rise, the microscopic algae die -- leading the coral to "bleach", a sign of starvation. 

 

Coral reefs create and protect the white sandy beaches tourists love

"When the temperature is even one degree above what they're used to, they shut down," Goreau says. "The coral expels them. The algae give coral -- which is actually transparent -- its color, so with no algae it looks white. It means the coral is starving." 

Once the coral starve to death, algae return to cover the limestone skeleton -- but it's the wrong kind of algae. Because coastal waters are so polluted, they nurture the growth of what Goreau calls "weed algae." 

"Coral and microscopic algae are [accustomed to] low-nutrient environment," Goreau explains. "Sewage provides excessive nutrients that bring useless, soft, fleshy fast-growing algae that doesn't provide much fish habitat. These weeds cover the limestone where coral larvae would settle." 

 

Three quarters of the world's coral reefs have been affected by the too-warm oceans of 1998

That's where mineral accretion comes in. The technology consists of a wire frame holding electrodes which shoot low voltage electrical currents into the water. This causes dissolved minerals -- including limestone -- to crystallize. 

"The limestone 'precipitates' out," Goreau explains. "It creates underwater limestone structures around the wire frame. Then we can either transfer coral onto the structure or let the larvae settle on it." 

And unlike artificial reefs made from junk metal or concrete, this skeleton doesn't rust or crumble, but only gets stronger with age -- and lets coral expend all its energy growing. 

"The coral we grew in the Caribbean were growing ten centimeters in ten weeks," Goreau says. "It usually takes a year for that species to do that." 

And according to Goreau, putting the technology in place is critical if we want any regrowth of the world's coral reefs -- 75 per cent of which were adversely affected by last year's tropical heat wave. 

"This is an emergency," Goreau says bluntly. "Last year, heatstroke killed more coral than any previous human action. It's the greatest environmental disaster ever." 

The U.S. State Department likely would agree. A report presented to the U.S. Coral Reef Task Force conference in Maui indicated that coral reefs have "suffered the most extensive and severe bleaching and subsequent mortality in modern record" due to warmer ocean temperatures. 

The problem, Goreau says, is that immediate global action is needed to stop climate change and restore the coral -- but because the problem is under water, people don't have to face it. 

"Coral loss would mean lost fisheries, lost tourism, eroded land," Goreau points out. "The only real solution is to stop global warming cold and begin restoration programs. But policy-makers aren't diving --so they don't see it." 

To find out more about mineral accretion and coral bleaching visit the Global Coral Reef Alliance website: http://globalcoral.org