Coral die-off could reach records in 2010

Warming causes “bleaching”

Jon Boyd, Oct 22, 10.

Coral death may reach record proportions in 2010 due to “bleaching,” according to a report by Climate Progress. Bleaching occurs when stressed organisms detach from the reef, which can be caused by prolonged warm water temperatures. Scientists are reporting warm water temperatures in the Caribbean, Indian Ocean, and the world’s richest coral environment, the Coral Triangle of Southeast Asia, says Climate Progress:

Scientists studying Caribbean reefs say that 2010 may be the worst year ever for coral death there. Abnormally warm water since June appears to have dealt a blow to shallow and deep-sea corals that is likely to top the devastation of 2005, when 80% of corals were bleached and as many as 40% died in areas on the eastern side of the Caribbean.

So Eli Kintisch reports at Science online. He explains:
Bleaching occurs when crucial microorganisms leave coral reefs during stress. Corals, which shelter a quarter or more of all marine species, get bleached, and may die, after prolonged heating. A few weeks of water temperatures a few degrees above normal can be fatal. During the 2005 die-off, for example, water temperatures off the Virgin Islands rose just 3°C above the average in August—but stayed that way until November. “There has been little recovery in the Caribbean since,” says reef specialist C. Mark Eakin of the U.S. National Oceanic and Atmospheric Administration (NOAA) in Silver Spring, Maryland.

But, as this NOAA graphic shows, 2010 is worse than 2005:

Caption: “The extent of warming in the Caribbean is more devastating in 2010 than 2005, previously the worst year for bleaching there.”

Kintisch reports:
“I’ve never seen bleaching like [it] in Panama,” said Nancy Knowlton, a coral biologist at the Smithsonian Tropical Research Institute in Panama who has been studying the local flora for 25 years. She and colleague Hector Guzman have seen massive reefs die in recent weeks in the enclosed lagoon of Bocas del Toro in Panama after becoming coated with giant sheets of slime, the remains of dead microorganisms. “This is NOT a normal condition on reefs, even bleached reefs. Where last year there were healthy corals, this year there was only gray ooze,” she wrote in an e-mail….

A number of factors besides water temperature can cause coral bleaching and die-offs, including pollution and storms. But temperature is the number-one culprit in such a massive die-off, says Eakin. The warmest 12-month period in the NASA temperature record ended this summer; June through August was the fourth-warmest such period in the record. The extent of the devastation across the Caribbean will become clear in the coming months as biologists measure the deaths.

The rest of this post is from Nick Sundt’s piece on the WWF blog, “Scientists Report One of the Worst Coral Bleaching Events on Record in Southeast Asia and the Indian Ocean.”

The Australian Research Council (ARC) Centre of Excellence for Coral Reef Studies said in press release yesterday (Worst coral death strikes at SE Asia, 19 October 2010) that[,] “[m]any 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.

The Coral Triangle – bordered by Indonesia, Malaysia and the Philippines — is one of WWF’s priority areas. It covers just one percent of the Earth’s surface, but is home to fully 30 percent of the world’s coral reefs, 76 percent of reef-building coral species and more than 35 percent of coral reef fish species. It also serves as vital spawning grounds for other economically important fish such as tuna.