快猫短视频

THE Great Barrier Reef is dying, crushed by an onslaught of rising ocean temperature, farming run-off, plagues of crown-of-thorns starfish, fishing and tourism. Better visit this rainforest of the oceans before it鈥檚 too late. Right?

Wrong. Far from being on its last legs, the reef is in glowing health. Indeed, according to the 2002 鈥淩eport on the Status of the World鈥檚 Coral Reefs鈥�, the reef is 鈥減redominantly in good condition鈥�, and just about pristine compared with reefs elsewhere in the world. So how has the perception that the reef is in imminent danger of collapse become entrenched in the public consciousness?

According to a small but increasingly vocal group of reef experts, the problem lies with scientists and conservation groups who have been distorting the health of the reef for their own ends, seeing this as a way of forcing politicians to ensure it is managed in an environmentally sound way, and making people take global climate issues seriously.

The experts agree that it would be no bad thing to tackle global warming (Australia along with the US refuses to ratify the Kyoto Protocol) and Queensland鈥檚 intensive farming practices, which if nothing else are having a detrimental impact on the state鈥檚 terrestrial ecology. They even agree that coral reefs around the world have taken a terrible hammering. But, they say, those who use the Great Barrier Reef as a stick to beat governments and farmers with are putting scientific credibility at risk. And that will undermine other efforts to protect the reef from current and future threats.

鈥淚magine they develop an agrochemical that really does kill corals. The farmers are going to stand up and say, 鈥榊ou said crown-of-thorns starfish and coral bleaching and sediment were killing the coral too.鈥� We would have lost our credibility,鈥� says marine physicist Peter Ridd of James Cook University in Townsville, Queensland.

Not everyone agrees. 鈥淚t鈥檚 a fine line between overselling the problem and improper complacency,鈥� says Miles Furnas, an oceanographer at the Australian Institute of Marine Science (AIMS) in Townsville. If the reef is beginning to show the first signs of wear and tear, as many coral experts suspect, then it is vital to act now. 鈥淭he dilemma of management means that if you wait long enough to see evidence of clear change, substantial damage has already occurred,鈥� he says.

At 2000 kilometres long, the Great Barrier Reef is one of the most diverse reef systems in the world, accounting for almost one-fifth of the world鈥檚 coral reefs. Add the fact that it鈥檚 fabulously photogenic and has World Heritage Area status, and you can see why the reef is an icon for environmentalists everywhere.

So reports that sediment, nutrients and agrochemicals washed down from Queensland鈥檚 sugar cane and cattle stations were wreaking havoc on the reef reverberated around the world, not least in articles published in this magazine. On paper it doesn鈥檛 look good. The Great Barrier Reef Marine Park Authority (MPA), the statutory body that manages the reef, asserts that over the past 150 years, sediment discharged from the mainland to the reef has increased by at least a factor of 3 and possibly a factor of 9, nitrogen by a factor of 2 to 4, and phosphate by a factor of between 3 and 15.

Worst still, pesticides such as Diuron have also been detected in sediments in the reef, it says. Just six months ago, a report containing those figures by a team of land-water and reef scientists helped nudge the Queensland state government and the federal government in Canberra into setting up a plan to deal with the problem.

But direct evidence that a problem actually exists is proving harder to come by. An extensive review in 2001 by ecologist David Williams of the Cooperative Research Centre for the Great Barrier Reef noted that only roughly a quarter of the inshore reefs, themselves a fraction of the whole reef system, are at risk even of 鈥減otential impacts鈥�. The report also acknowledged that establishing whether a reef has been damaged by agricultural run-off has proved nigh-on impossible for a variety of reasons, including frequent natural disturbances such as cyclones, and because monitoring has only been in place for the past 20 years or so. Williams nevertheless says there is cause for concern in circumstantial evidence, which suggests that at least some of the inner reefs are threatened by agricultural run-off.

Ridd agrees that agricultural run-off could in theory pose a threat, but he is categorical that it won鈥檛 be due to sediment. His studies have shown that any sediment from rivers is swamped by the amount lifted from the sea bottom by waves. More work needs to be done on pesticide and nutrient run-off to see if this is having an impact, but Ridd believes that ecologists and environmentalists tend to underestimate how much these pollutants are diluted once they reach the ocean. 鈥淛ust because you can a show an increase in fertiliser use or detect pesticides in subtidal sediments, it doesn鈥檛 mean that there鈥檚 a problem. But it gets picked up by Greenpeace 鈥� and why shouldn鈥檛 it be, when it鈥檚 come from the Great Barrier Reef Marine Park Authority?鈥� he says.

Furnas is not reassured by these arguments. 鈥淲e have never seen a reef in the Great Barrier Reef clobbered by nutrients or sediment. But what we are seeing 鈥� the low coral cover, and low diversity 鈥� is possibly the beginning of the process.鈥� That, combined with the unequivocal evidence that coral reefs from Hawaii to Hong Kong have been damaged by agricultural run-off, is reason enough to take action now. He accepts, however, that some scientists may have exaggerated the problem. 鈥淪cience is a human endeavour, just like politics and journalism, and sometimes they put a spin on it.鈥�

Even more disturbing, at first sight, than the threats of agricultural run-off are reports that global warming is killing the reef by bleaching coral. 鈥淪outhern and central sites of the Great Barrier Reef are likely to be severely affected by sea temperature rise within the next 20 to 40 years,鈥� said Ove H酶egh-Guldberg, director of the Centre for Marine Studies at the University of Queensland, in a 1999 study commissioned by Greenpeace. The average sea temperature on the reef has increased by 0.3 掳C since the end of the 19th century, and huge tracts of the reef have certainly been bleached on two occasions in the past five years.

Corals bleach when they spit out the symbiotic algae that they depend on to provide carbohydrates through photosynthesis. The favoured theory goes that when the sea is too warm, and conditions too sunny, the algae go into photosynthetic overdrive, spewing out so many dangerous free radicals that the coral are forced to eject them. If temperatures drop soon enough, the algae and coral happily reunite. But if the coral are deprived of their food source for too long they starve to death.

It鈥檚 a compelling story. Indeed, of all the potential threats to the reef, this is the one on which there is most agreement. Nonetheless, in the rush to sound the alarm, the uncertainties about bleaching 鈥� a phenomenon that has been under the microscope for only four yearsor so 鈥� have been lost from the message. In 1998, 16 per cent of the world鈥檚 reefs bleached. 鈥淭he scientists took one look and thought they were dead. But what we are seeing is that about half the reefs that were severely damaged are recovering,鈥� says Clive Wilkinson, a coral reef expert at AIMS and editor of the 鈥淩eport on the Status of World鈥檚 Coral Reefs鈥�. Meanwhile, on the reef, the patterns of bleaching in the 2002 event were mysteriously different from the 1998 event, with some corals that were supposedly supersensitive to bleaching, such as the hard coral family Pocilloporidae, surviving well. 鈥淚t鈥檚 a real conundrum,鈥� says Wilkinson.

None of this means that coral bleaching isn鈥檛 cause for concern. It might subtly change the reefs鈥� composition, even if it doesn鈥檛 kill them. But coral experts understand far less about the threat posed by bleaching than conservation groups and some scientists like to suggest.

Meanwhile, plagues of crown-of-thorns starfish, which suck the polyps out of coral skeleton, have descended on the reef three times since the 1960s, including the current outbreak. During each onslaught, coral experts have claimed that the reef won鈥檛 recover. Yet so far it always has. Similar alarmist stories have circulated at different times that link overfishing, tourism and shipping damage to the demise of the reef.

But how have reports of potential and future threats to the ongoing health of the reef become twisted into perceptions that it is already dying? One reason may be the temptation to overstate the problems to win research dollars. 鈥淚鈥檝e done it,鈥� says Ridd. 鈥淚 would hate to look through my old grant proposals. We push the worst-case scenarios to show how important our research is.鈥�

A slight exaggeration by scientists may get amplified once it has been passed on by the media and environmental groups like Greenpeace and WWF. 鈥淚t鈥檚 the challenge of trying to sell the precautionary story,鈥� says Paul Marshall, manager of coral bleaching issues at the Great Barrier Reef MPA. 鈥淚 try hard to distinguish between coral bleaching and coral dying,鈥� he insists. 鈥淏ut the whiteness looks so spectacular, and that鈥檚 what the media runs with. The idea that white coral isn鈥檛 necessarily dead gets lost.鈥�

One expert who admitted that the evidence is wanting, still told 快猫短视频 he had a 鈥済ut feeling鈥� that something is wrong with the reef. Sentiments like that, combined with the real passion many scientists feel for protecting the reef鈥檚 future, may be all it takes to see the ambiguities dropped from the message.

Take a recent Great Barrier Reef MPA brochure on water quality 鈥� a distillation of the longer report that convinced the government to act on water quality on the reef. While detailing changing farming practices in Queensland, and the devastation wreaked by agriculture on reefs in other parts of the world, it fails to mention that there is no direct evidence of any damage to the reef, and that only small areas are even under threat. While not exactly inaccurate, says Ridd, the brochure and the report, which is posted on the Great Barrier Reef MPA website, are deceptive. Another researcher says the brochure 鈥渒ills with the weight of innuendo鈥�.

H酶egh-Guldberg, for one, categorically denies overstating any threat to the reef. He points out that researchers who have raised the alarm have had an uphill battle to force government and industry to take the threats seriously. But other coral experts believe the danger flag has been waved enough. The limited amount of money available for environmental protection needs to be divvied out on the basis of hard scientific facts, not emotional horse trading, they say. Scientific credibility is too precious to squander, especially when it comes to the Great Barrier Reef.