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Australia
researching if reef can survive 'bleaching' MSNBC
Staff And Wire Reports, July 25, 2002 Sydney, Australia - Sea temperatures around Australia's Great Barrier Reef early this year were the warmest on record, scientists reported Thursday, and a developing El Nino weather system poses a further threat to the reef's temperature-sensitive coral. Government scientists said warmer temperatures stressed 60 percent of the coral on the reef, the world's largest living organism at 133,300 square miles. The coral becomes stressed, or bleached, when warmer temperatures break down the symbiotic relationship between coral and algae living inside. During bleaching, the algae leaves the coral, disrupting the growth as well as color of the coral, leaving it white. In severe cases the coral will die. The report comes from the Australian Institute of Marine Science, which just completed an atlas of sea temperatures over the past decade and amalgamated it with historical data to show 2002 was the warmest year for water temperatures off northeast Australia since 1870. "Unless the corals can adapt and become acclimatized, then obviously the long-term future for the coral is at risk," said Craig Steinberg, an oceanographer at AIMS, an Australian government agency. "The outlook isn't good. If coral can't adapt then they're going to bleach and you get mass mortality." The sea temperature over the last century has risen by just half a degree Celsius. But corals tend to live within 1 to 2 degrees of their maximum temperature threshold, and a tiny increase is therefore enough to ensure a major impact.
Bleaching in early 2002 covered 60 percent of the reef, even more than the 1998 event that made headlines worldwide. "Until now, the coral bleaching episode in 1998 was the worst on record," researcher Ray Berkelmans, who headed an aerial survey of the reef, reported in May. "But the 2002 event was probably worse because more reef area was affected. The most severe bleaching occurred on reefs close to shore in both bleaching events, but the 2002 event has affected a greater area of reefs further offshore." On the positive side, it appeared likely that most reefs would recover with only a minor number of coral deaths. The 1998 bleaching was tied to an El Nino, which warms the waters of the Pacific. The onset of another El Nino this year, albeit one that U.S. experts say is likely to be mild, has increased the chances of another southern hemisphere summer of high sea water temperatures at the start of 2003.
The bleaching in early 2002 was not during an El Nino year, making the high temperatures even more unusual. AIMS climate expert Janice Lough said that points to another possible culprit: global warming. "Reef managers can do all they can to reduce all the other threats to coral reefs but they can't solve individually the global problem (of climate change)," said Lough. Whether warming is part of a natural climate shift, or due to human emissions of certain gases like carbon dioxide, is still being debated. "We still do not know the relationship between global warming and natural variability," said Penehuro Lefale, a researcher with New Zealand's National Institute of Water and Atmospheric Research. "So it's a bit too early to look at that." Speaking to reporters at a conference hosted by SeaWeb, a marine science advocacy group, Lefale appealed to South Pacific governments to resist financial pressure to remove long-standing weather stations, arguing that they will provide the historical data needed to study the climate change connection.
Coral can recover after mild bleaching but researchers fear that its ability to overcome heat stress may be weakened if high temperatures become more common. This image taken last February shows Great Barrier Reef coral that has bleached due to warmer temperatures. AIMS researchers are trying to establish whether coral has the ability to adapt quickly to changing temperatures. There is evidence that they can over long periods of time, but so far no indication of any short-term ability to acclimatize. Long-term adaptation could see some types of coral die-off and be replaced by more resilient coral. "It's not so much that the reef will die, it's that the reef will change," Lough said. "If you sort of knock out certain of the corals then other organisms might take their place." Terry Done, AIMS' lead researcher on bleaching, called for more research but wasn't hopeful about the reef's future. "We may be witnessing the beginning of a slow-motion degradation of the reef system that will only get worse in coming decades," he said last May.
Straddling the equator, reefs are found around the globe and what's happened at the Great Barrier Reef has happened elsewhere as well. One approach to protecting reefs is to find out which ones have proven resilient to bleaching and then ensure that they get protection against other threats, such as the trade in coral for aquariums and fishing that destroys reef to get to the fish. "If we find an area with resistant corals they should get protection," Andrew Smith, a scientist with The Nature Conservancy, told the SeaWeb conference. "We can't stop coral bleaching but hopefully we can maximize corals' ability to recover." The Nature Conservancy is funding a pilot project in Palau, a South Pacific island nation, where some protected marine reserves will be redrawn to incorporate resilient reefs. The group and others are also drafting guidelines to present to the World Parks Congress in 2003. Additional information about bleaching on the Great Barrier Reef, as well as AIMS' new atlas, are online at http://www.aims.gov.au. MSNBC.com's Miguel Llanos as well as Reuters contributed to this story. Source: http://www.msnbc.com/news/785357.asp
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