ARC Centre of Excellence for Coral Reef Studies Science Alert 19 Oct 10;
International marine scientists say that a huge coral death which has struck Southeast Asian and India Ocean reefs over recent months has highlighted the urgency of controlling global carbon emissions.
Many reefs are dead or dying across the Indian Ocean and into the Coral Triangle following a bleaching event that extends from the Seychelles in the west to Sulawesi and the Philippines in the east and include reefs in Sri Lanka, Burma Thailand, Malaysia, Singapore, and many sites in western and eastern Indonesia.
“It is certainly the worst coral die-off we have seen since 1998. It may prove to be the worst such event known to science,” says Dr Andrew Baird of the ARC Centre of Excellence for Coral Reef Studies and James Cook Universities. “So far around 80 percent of Acropora colonies and 50 per cent of colonies from other species have died since the outbreak began in May this year.”
This means coral cover in the region could drop from an average of 50% to around 10%, and the spatial scale of the event could mean it will take years to recover, striking at local fishing and regional tourism industries, he says.
The bleaching event has also hit the richest marine biodiversity zone on the planet, the ‘Amazon Rainforest’ of the seas, known as the Coral Triangle (CT), which is bounded by Indonesia, Malaysia and the Philippines.
“Although the Coral Triangle is the richest region for corals on Earth, it relies on other regions around its fringes to supply the coral spawn and fish larvae that help keep it so rich,” Dr Baird explains. “So there are both direct and indirect effects on CT reefs which will affect their ability to recover from future disturbance.”
“Also the reefs of the region support tens of millions of people who make their living from the sea and so plays a vital role in both the regional economy and political stability. For example, in Aceh, northern Sumatera, where the bleaching is most severe, a high proportion of the people rely on fishing and tourism for their livelihoods. While it may take up to two years for some fish species to be affected by the loss of coral habitat, fisheries yields will decline and this combined with a drop in the number of dive tourists visiting could have major long-term effects on the local economy.”
The cause of the bleaching event was a large pool of super-hot water which swept into the eastern Indian Ocean region several months ago, shocking the corals and causing them to shed the symbiotic algae that nourish them, thereby losing color and “bleaching”. If the corals do not regain their algae they starve to death.
According to the National Oceanic and Atmospheric Administration’s Coral Hotspots website, sea surface temperatures in the region peaked in late May, 2010, and by July the accumulated heat stress was greater than in 1998. Local dive operators recorded water temperatures of 34 C, over 4 degrees higher that than long term average for the area.
The event was first detected on reefs in Aceh by marine ecologists from Wildlife Conservation Society, CoECRS and Syiah Kuala University. They already rate it as one of the worst coral diebacks ever recorded.
“My colleagues and I have high confidence these successive ocean warming episodes, which exceed the normal tolerance range of warm-water corals, are driven by human-induced global warming. They underline that the planet is already taking heavy hits from climate change – and will continue to do so unless we can reduce carbon emissions very quickly,” Dr Baird said.
“They also show this is not just about warmer temperatures: it is also threatening the livelihoods of tens of millions of people and potentially the stability of our region.”
Dr Baird said it was not yet clear whether Australia would suffer a similar coral bleaching event this year: this would emerge only with the arrival of warmer waters from the north in January/February 2011. The previous worst events to strike the Great Barrier Reef were in 1998 and 2002, when over 40% of the reefs along the length of the GBR were affected.
Scientists say Asia's corals dying en masse
Yahoo News 19 Oct 10;
SYDNEY (AFP) – Coral reefs in Southeast Asia and the Indian Ocean are dying from the worst bleaching effect in more than a decade, Australian marine scientists said Tuesday.
The bleaching, triggered by a large pool of warm water which swept into the Indian Ocean in May, has caused corals from Indonesia to the Seychelles to whiten and die, Australia's Centre of Excellence for Coral Reef Studies said.
Reefs in the Philippines, Sri Lanka, Myanmar, Thailand, Malaysia and Singapore were also affected by the phenomenon under which sea temperatures rose by several degrees Celsius in Indonesia, researcher Andrew Baird said.
"It is certainly the worst coral die-off we have seen since 1998. It may prove to be the worst such event known to science," he said.
Baird, a fellow at James Cook University, said the magnitude of the event was so large, and the ocean temperatures in some places raised so much higher than normal, that it was "almost certainly a consequence of global warming".
He said for six to eight weeks from mid-May the temperatures were high enough to cause bleaching of the corals in Indonesia's Aceh, the area worst hit by the event.
"You jump into the water and you are just surrounded by white and dead corals," he said. "It is an extraordinary sight. The locals tell us they have seen nothing like this before."
Baird said the massive die-off was expected to compare in scale and magnitude to the damage caused in 1998, when warmer water bleached reefs globally and about 16 percent were seriously degraded.
"This is the second big global bleaching event that we have documented," he told AFP.
"The scale of the event is so large that it is going to take reefs a long time to recover," he added.
The bleaching is caused by the warm water sweeping over the reefs, shocking the corals and causing them to shed the algae which nourish them. If corals fail to regain their algae, they starve to death.
Baird said it was too early to say whether Australia's Great Barrier Reef, a major tourist attraction swarming with marine life, would be damaged but that he expected bleaching to affect reefs in the Andaman Sea and central Pacific.
"Once the reef dies you lose both live coral cover, which lots of fish need... but then everything that feeds on them will disappear as well," he said, adding that he expected some fish species to decline within a year.
He said in Aceh alone, an area with some unique marine creatures, there would be a loss of biodiversity.
"There's a very good chance that there will be some local extinctions both of endemic fish and of coral," he said.
Baird said the reefs could take years to recover, heavily impacting fishing and tourism in the region and could become a security issue.
"It's one of the reasons that countries like Australia need to act quickly and decisively on climate," he said.
Scientists say corals are vital to marine life because they provide habitats for a vast variety of creatures and absorb large levels of poisonous carbon dioxide.
