DR LYLE Vail says coral is very resilient, but it can only take so much.

Vail is director of the Lizard Island Research Station 220km north of Cairns where he has been for 24 years.

“Coral has ways of flicking off sediment,” he said last week. “But if there is too much sediment, the coral gets tired, cannot keep up and gets buried.”

As it happens he was speaking the day before the Federal Government announced approval for Australia’s largest coalmine -- the $16.5 billion Carmichael Coal and Rail Project in Queensland's Galilee Basin.

The coal will be exported through the Great Barrier Reef. It will require port dredging and/or moving coal from barges to larger ships at sea.

Either way, increasing sediment is inevitable.

The ship-to-ship transfer of coal near the Great Barrier Reef seems madness.

I was at the Lizard Island station this week. It is run by the NSW Government’s Australian Museum, but gets most of its funding through the Lizard Island Research Foundation.

Vail explained how threatened the reef is from human activity.

About half the reef has been lost since 1986. Forty per cent of the loss can be put down to the crown of thorns starfish. But crown of thorns outbreaks are not some natural event, but most likely triggered by human intervention of one kind or the other.

The research station received a $500,000 donation from the Potter Foundation last month to help find the cause of crown of thorns outbreaks. There are several theories being tested.

“Outbreaks can result in tens or hundreds of thousands of starfish each eating about six square metres of coral a year,” Vail says. “They are voracious. They strip away all living coral.”

One theory is that overfishing has resulted in fewer predators of starfish and their eggs.

Another is that mainland fertiliser run-off is putting more nitrates into the water giving rise to more plankton and therefore greater chance of young starfish surviving and making it to a reef. Usually, very few of the 60 million eggs that the average female produces at spawning will make it.

The other threats to the reef are warmer waters; more acidic waters; and more storm damage. All three are most likely caused by climate change.

There is some evidence that there have been fewer cyclones recently, but they have been stronger. The eye of Cyclone Ita for example hit Lizard Island on 11 April at Category 5. There has been extensive damage to coral from waves and debris in some places, but virtually none in others.

Some of the giant clams, for which Lizard Island is renown, were also wiped out. They take about 50 years to get to full size of 1.5 metres.

Vail points out that storms also kick up sediment that has laid dormant for a long time, stirring up chemical and organic pollutants from more polluting times.

The coral can grow back, even hundred-year old bommies that have been  knocked over by cyclones. It is resilient. But there is a limit if there are other threats, such as warmer or more acidic water.

If the ocean gets a degree or two warmer or a warm patch moves on to parts of the reef it can cause bleaching. 

The sac of each coral polyp contains a one-celled algae called zooxanthellae. Through photosynthesis it fixes carbon and produces sugars for itself and the coral, giving off oxygen. But in warmer water its metabolism speeds up and it gives off too much oxygen. The coral thinks it is being poisoned and expunges the algae. The algae give coral its colour, hence the bleaching.

Corals can survive a bleaching event, because not all their food comes from the algae. But often they die, and the area taken over by ugly seaweed. If it becomes too widespread, tourism will die with it.

Coral is more likely to die if there are other threats around, such as extra carbon dioxide.

About half of carbon dioxide emissions end in the ocean. It results in greater acidity. That in turn makes the build up of calcium by corals more difficult.

“It is like giving coral osteoporosis,” Vail says.

A large coal mine, of course, will not help.

Single large interests – such coalmining – have more political clout than the myriad of interests whose livelihoods depend on the reef – especially tourism and fishing.  We are slowly killing the thing people come to see. 

Worse, governments are down-playing the damage.

Last week the chief executive of the Australian Institute of Marine Science, John Gunn, said assessments of the Great Barrier Reef compiled by the federal and Queensland governments buried bad news of the reef’s decline.

He told a Senate inquiry, “For example, the statement that ‘at the scale of the GBR region, most of its habitats and species are assessed to be in good to very good condition’ may be technically correct, but as most of its key habitats and vulnerable species (corals, seagrasses, seabirds, dolphins, dugong, turtles) are in very poor to poor condition and declining in the southern GBR, it would seem appropriate to lead with this point.”

The need to monitor the reef is greater than ever, but the system for assessing the environmental impact of industrial development near the reef was flawed.

Developers, such as those building ports or dredging the seabed, commission consultants to assess the potential impact of work. Their reports go to the Great Barrier Reef Marine Park Authority, which is responsible for the health of the reef.

The conflict of interest is obvious. The authority should commission the work and the developer pay for it, Gunn argued.

Further, the federal government has cut funding for the Great Barrier Reef Marine Park Authority. And it wants to hand over environmental approvals to the states – in the interests of cutting red tape, but really to give the Coalition’s donors their pay dirt, irrespective of broader interests.

Australia will not miss another coal mine but Australia without the Great Barrier Reef is unimaginable.