New wave of coral bleaching sweeps the planet

Posted: 28 October 2002

A new wave of bleaching has swept coral reefs world-wide with scientists linking the events to climate change. Over 400 cases of bleaching, a phenomenon linked with increased seawater temperatures which can damage and even result in the death of a reef, were documented by a researchers in the first nine months of 2002.

The majority of bleaching records have come from the Great Barrier Reef in Australia with others from reefs in countries including the Philippines, Indonesia, Malaysia, Japan, Palau, the Maldives, Tanzania, the Seychelles, Belize, Ecuador and off the Florida coast of the United States.

The findings, released in October 2002, by the WorldFish Center, the InternationalCoral Reef Action Network (ICRAN) and the UN Environment Programme (UNEP), have come from a new global coral reef information system called ReefBase which contains data on bleaching events dating back to 1963.

ReefBase has been set up by the WorldFish Center as part of ICRAN, a global network of more than 10 international agencies aimed at boosting the fortunes of coral reefs by developing sustainable ways of managing them. ICRAN is funded through UNEP by the United Nations Foundation.

Second worst year

Dr Meryl Williams, Director General of the WorldFish Center in Penang,Malaysia, said: "Twenty countries in all the major oceans have so far this year documented over 430 cases of bleaching. This makes 2002 the second worst year for the phenomenon after the major bleaching events of 1998 which were linked with the very strong El Nino, climatic event, of that year.

She added: "While the impacts are much less than in 1998, we are very concerned at what the short and long term impacts are going to be on the reefs themselves and the people who depend on them. A lot will hinge on how well the reefs recover from these latest events and if further bleaching events occur over the coming years".

Klaus Toepfer, UNEP's Executive Director said "Coral reefs are under threat world-wide from a variety of pressures including unsustainable fishing methods, such as dynamite and cyanide fishing, insensitive tourism, pollution and climate change. Every effort is needed to conserve these vital habitats for fish and other marine life for the benefit of local people who rely upon them for protein and livelihoods".

Coral bleaching occurs when stressful conditions such as high temperatures cause corals to expel the microscopic algae that live in their tissues. The algae provide essential food energy for corals.

Information is crucial

Dr Jamie Oliver, project leader of ReefBase and chair of the ICRAN Steering Committee, said: "Reliable and publicly available information on the frequency, intensity and location of coral bleaching is vital for informed debate about the causes and consequences of these events. Such information is also crucial for making the sound decisions needed to protect and conserve reef systems".

ReefBase currently holds over 3,800 records going back to 1963 which include information on the severity of bleaching. This is important in order to distinguish between low-level bleaching, which has probably always occurred on coral reefs, and recurrent, massive bleaching of entire reefs, which may be a new phenomenon related to climate change.

Dr Oliver added: "The database shows an increase in the frequency and intensity of bleaching, as well as a rise in the number of countries affected. While some of this may be due to increased awareness of the problem, the phenomenon has been well known among divers and scientists for many years, so the trend is almost certainly real".

"It is too early to determine what level of mortality will occur as a result of the current bleaching, but based on previous events we can expect a significant number of reefs to suffer loss of corals which could take many years to replace," he said.

Australia's Great Barrier Reef, the largest coral reef system in the world, was severely affected, with 2002 being the worst bleaching event on record.

For more information see reefbase and unep