New research points way to restore coral reefs

Posted: 14 July 2008

Experts attending the 11th International Coral Reef Symposium in Florida, say that the reefs can be regenerated using the same methods as are used to restore tropical forests. Our contributing editor, Henrylito Tacio, reports from the Symposium in Florida.

Reforestation is the restocking of existing forests and woodlands which have been depleted. It also refers to afforestation, the process of restoring and recreating areas of woodlands or forest that once existed but were deforested or otherwise removed or destroyed at some point in the past.

In a similar way, degraded coral reef ecosystems can also be restored, using similar technique, says Dr. Baruch Rinkevich, a senior scientist with the Israel Oceanographic and Limnological Research.

Cup corals feeding
Cup corals feeding
Cup corals feeding. Photo © Chuck Savall
"Many of the world's coral reefs are experiencing a severe degradation," said Dr. Rinkevich. These ecologically-fragile marine wonders can be saved by using "branching corals" as "ecosystem engineering species."

In a press conference during the Symposium, the Israeli scientist talked about the so-called "gardening coral reefs concept," a method inspired from forest restoration guidelines.

The technique involves generating and farming large stocks of new coral colonies in a floating nursery which is far from predators and other disturbances. After one year or so, they are transplanted into degraded areas.

"In past efforts, we have taken coral colonies from healthy localities and transplanted them into denuded areas," Dr. Rinkevich said. "This method resulted in low survival rates and inflicted stress on donor coral colonies."

Transplanted colonies

In their study, they selected five denuded knolls somewhere in Eilat's Reef in Red Sea. "Eilat's coral reef is the world's most northern reef," said Yael Horoszowski, who did the study. "This reef, which was classified in the past among the richest and most biodiversed reefs, has been in decline for the past forty years."

In November 2005, they transplanted 550 nursery-grown colonies of two branching coral species. Three-hundred more colonies were transplanted in May 2007.

During the first two years of monitoring, they observed that few of these transplanted corals died. "We also found out that there was an increase of marine species like fish and crabs as we literally brought new 'homes' to them," said Horoszowski.

In Indonesia, Dr. Helen Fox is doing another method of restoring degraded reefs caused by destructive fishing with explosives (dynamite or homemade bombs). The work was done in Komodo National Park. Sustained by rushing currents where the Indian and Pacific Oceans meet, the park is home to a staggering marine biodiversity. To the north, coral reefs sparkle. To the south, manta rays and filter-feeding whales glide through choppy, nutrient-rich waters.

Rock piles

"Blast fishing causes widespread and devastating damage to coral reefs," said Dr. Fox. "Despite being illegal, blast fishing continues to be a threat to reefs in the national park."

In restoring the degraded reefs, Dr. Fox and her team used rock piles as "a low-tech, locally-available reef rehabilitation method." In 2002, they installed four different configurations of rock piles at four sites.

The team observed that the rock piles were able to stabilize the rubble caused by explosives. It also attenuated the water currents, recreated "the three-dimensional structure" of an intact reef, and provided surfaces for coral recruitment and refuges for other marine species.

Although these two methods are very successful in restoring degraded reefs, Dr. Fox reiterated that it is "cheaper and more efficient to prevent the damage in the first place."

Annual loss

Living coral reefs are the foundation for many marine species, including fish, crabs, oysters, and clams. They also provide extensive recreational and tourism opportunities.

Reef-building corals grow where the water is clear, warm, and shallow. These conditions occur in tropical waters near the equator, on the eastern sides of continents, and around oceanic islands.

In the United States, half the coral reefs are in trouble. According to the the World Conservation Union (IUCN), one third of the world's coral reefs are threatened with extinction.

For the last two decades, Indo-Pacific reefs have shrunk by 1 per cent each year - a loss equivalent to nearly 600 square miles (1,553 square kilometers). That makes the rate of reef loss about twice the rate of tropical rain forest loss.

"We have to do something now before we lose our coral reefs forever," urged Dr. Rinkevich. "Restoring them using the way tropical forests are rescued is a good start." Read more reports on the 11th International Coral Reefs Symposium in the Coasts and Oceans section of this website.

Related link:

A third of all coral reefs face extinction