Asia–Pacific Analysis: Protecting and restoring coral reefs

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Courtesy of Courtesy of SciDev.Net

Better navigation and surveillance can help to prevent ships from damaging coral reefs and the need for expensive restoration, says Crispin Maslog.

When the US Navy minesweeper USS Guardian smashed into the Tubbataha Reefs in the Sulu Sea off the Philippines at dawn on 17 January, it sent shock waves to the Philippine government and environmental guardians in South-East Asia.

Despite the ship's sophisticated navigational equipment, the US Navy blamed 'faulty navigation chart data' for the grounding.

The big question though is whether the coral reefs can be returned to their former state and at what cost?

Coral reef rehabilitation is expensive and labour-intensive. It has to be done with extreme care by experts because the work 'may cause damage if coral colonies or fragments for transplantation are taken from healthy reefs'. [1]

Reef recovery can also be sluggish. 'If the reef is pulverised, the recovery is dependent on coral recruitment from adjacent unaffected reefs and the growth of these recruits is very slow. But if there are coral fragments, some of these can reattach themselves and hasten recovery', said Hilconida Calumpong, director of the Silliman University's marine laboratory, Philippines, in an email interview.

The Tubbataha Management Office that manages the reef says that about 4,000 square metres of the reef were damaged in the accident. The US government has apologised and offered US$100,000 to rehabilitate the reefs. In 2005, the same area suffered damage after the Greenpeace ship Rainbow Warrior ran aground, for which it was fined about US$7,000.

Debate after the latest grounding focused on how to dislodge the 1,300-tonne, 68-metre-long minesweeper while causing as little damage as possible to the reefs. The final decision is to break up the vessel and ship it out in pieces.

Tubbataha, which covers 130,000 hectares, was proclaimed a national marine park in August 1988 by then Philippine President Corazon Aquino and a World Heritage Site by UNESCO (the UN Educational, Scientific and Cultural Organization) in 1993. The reefs are in the northern part of the Coral Triangle, which spans 5.7 million square kilometres of ocean waters from the southern Philippines to Malaysia, Indonesia, Papua New Guinea, the Solomon Islands and Timor-Leste in the Pacific. [2]

Growing threats

The latest Tubbataha accident highlights the threat that commercial as well as naval shipping pose to the world's reefs. Other threats include overfishing, population pressure from coastal development, runoff from agriculture, oil exploration and climate change.

With the gross tonnage of international commercial shipping having increased by 67 per cent since 1980, and with most reefs — unlike Australia's Great Barrier Reef — subject to few shipping restrictions, one can imagine that more shipping incidents are likely to happen.

On 3 April 2010, the Chinese coal carrier Shen Neng 1 ran aground at full speed on the Great Barrier Reef. [3] The 230-metre vessel, carrying 975 tonnes of fuel oil and 65,000 tonnes of coal, was refloated on 12 April, but only after it had damaged 400,000 square metres of the reef, the equivalent of 58 football pitches.

The first lesson to take from these accidents is the need to develop more sophisticated security networks for reefs. These would include updated navigation charts, air surveillance and the installation of radar and communications equipment that would help park rangers and the coast guard to both prevent collisions and coral reef groundings, and keep tabs on marine poachers.

Rehabilitation strategy

With the growing sea traffic, however, groundings cannot be eliminated. Governments and coral reef guardians must therefore develop a more efficient and effective coral rehabilitation capacity. They could learn from the experience of the Florida Keys National Marine Sanctuary in the United States. 

In August 2002, an 11-metre-long boat, Lagniappe II, ran aground on a shallow coral reef near Key West in Florida, destroying around 35 square metres of coral. The boat's owner paid US$56,700 for the damage. Sanctuary staff hired restoration biologists who used special cement that hardens under water to reattach 473 corals and coral fragments that were dislodged by the grounding. [4]

The restoration efforts were monitored, using digital photographs and computer software, to count the types and amounts of coral in the damaged area, with an adjacent unaffected site used as a reference. By 2009, the reattached coral fragments looked the same as the adjacent uninjured coral colonies. A year later, the amount of coral at the restoration site was higher than at the reference site.

For Tubbataha, Philippine officials are looking at using similar technology. Currently, a number of experimental coral farms have been set up around the country to produce coral to replace damaged reefs around the archipelago.

Coral farming involves collecting fragments of live corals that are placed in cement discs, fastened by nylon wires onto metal wire trays that themselves fit onto larger platforms. Around 600 fragments can be accommodated per platform. Each week, divers check and clean the coral fragments.

After a fragment has grown to an adequate size, part of it can be recut to produce further fragments. Hundreds of thousands of fragments can be reproduced using this procedure, speeding up reef restoration. [5]

Although restoring reefs to a good state of health is expensive and takes about a decade, the good news is that even seriously damaged coral reefs can be rehabilitated.

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