Another worrying year for globe’s coral reefs

By United Nations Environment Programme

A new wave of bleaching has swept coral reefs worldwide 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, have been documented by a researchers so far this year.

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 today by the WorldFish Center, the International Coral Reef Action Network (ICRAN) and the United Nations 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.

Dr Meryl Williams, Director General of the WorldFish Center in Penang, Malaysia, said: “20 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”.

Coral reefs under threat

Klaus Toepfer, UNEP’s Executive Director who is attending the COP8 climate change talks taking place in New Delhi, this week, 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”.

What causes coral bleaching?

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.

Dr Jamie Oliver, project leader of ReefBase and chair of the ICRAN Steering Committee whose Board of Directors is meeting in Washington DC tomorrow, 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”.

Coral bleaching database

ReefBase, which can be viewed at, 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”.

Great Barrier Reef suffers

“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.

Virginia Chadwick, chair of the Great Barrier Reef Marine Park Authority (GBRMPA), said: “The current trends are cause for concern both for Australia and the rest of the world. We need to continue to monitor the situation by collecting accurate information using survey techniques, such as those developed in Australia, and to make these results publicly available through the GBRMPA websites as well as global sites such as ReefBase”.

Rising temperatures

ReefBase is also working closely with the United States’s National Oceanic and Atmospheric Administration (NOAA) to match bleaching events with global sea surface temperatures. It is planned to create automatically updated maps displaying bleaching events with NOAA’s Index of Temperature Anomalies.

Dr Alan Strong, Team Leader in NOAA’s Oceanic Research and Applications Division and Coordinator of NOAA’s C Reef Watch Program, said: “We have found a strong correlation between our Degree Heating Week index and coral bleaching events and can often provide real-time predictions of bleaching for some areas such as observed late this summer in the most north-western Hawaiian Islands at Midway and most certainly at Howland and Baker Islands near the Equator”.

Data contribution

Scientists, marine park managers and other experts are being urged to provide data on bleaching, coral mortality and recovery to ReefBase.

“That way we can provide people with information on how well coral reefs are recovering or adapting to climate change. At present the signs are not good, but we need to make sure that any conclusions are based on a comprehensive analysis of all the available data. ReefBase is a key instrument for achieving this goal,” said Dr Oliver. — News released 28 October 2002.

Photo 1: Bleached Acropora and partially bleached Porites with other unaffected corals
Photo 2: Bleached Brain coral (Symphyllia sp.)
Photo 3: Partially bleached Favia sp. and sea urchin
Photo 4: Partial bleaching on the upper part of Porites sp

All photographs were taken at Pulau Payar Marine Park between August 3-6, 2002 by Yusri bin Yusuf. Photographs courtesy of ReefBase: A Global Information System on Coral Reefs, a project by WorldFish Center, with support from the International Coral Reef Action Network (ICRAN).