Storms to starfish: Great Barrier Reef faces rapid coral loss

* Great Barrier Reef suffers unprecedented coral loss
* Study says storms, starfish, bleaching cause most damage
* Risk of rapid decline unless world adopts tough CO2 goals

David Fogarty Reuters 2 Oct 12;

SINGAPORE, Oct 2 (Reuters) - The world's largest coral reef - under threat from Australia's surging coal and gas shipments, climate change and a destructive starfish - is declining faster than ever and coral cover could fall to just 5 percent in the next decade, a study shows.

Researchers from the Australian Institute of Marine Science (AIMS) in the northeastern city of Townsville say Australia's Great Barrier Reef has lost half of its coral in little more than a generation. And the pace of damage has picked up since 2006.

Globally, reefs are being assailed by myriad threats, particularly rising sea temperatures, increased ocean acidity and more powerful storms, but the threat to the Great Barrier Reef is even more pronounced, the AIMS study published on Tuesday found.

"In terms of geographic scale and the extent of the decline, it is unprecedented anywhere in the world," AIMS chief John Gunn told Reuters.

AIMS scientists studied data from more than 200 individual reefs off the Queensland coast covering the period 1985-2012. They found cyclone damage caused nearly half the losses, crown-of-thorns starfish more than 40 percent and coral bleaching from spikes in sea temperatures 10 percent.

The starfish are native and prey on the reefs. But plagues are occurring much more frequently.

Ordinarily, reefs can recover within 10 to 20 years from storms, bleachings or starfish attacks but climate change impacts slow this down. Rising ocean acidification caused by seas absorbing more carbon dioxide is disrupting the ability of corals to build their calcium carbonate structures. Hotter seas stress corals still further.

Greens say the 2,000 km (1,200 mile) long reef ecosystem, the centre-piece of a multi-billion tourism industry, also faces a growing threat from shipping driven by the planned expansion of coal and liquefied natural gas projects.

Those concerns have put pressure on the authorities to figure out how to protect the fragile reef.

FALLING FAST

The researchers say the pace of coral loss has increased since 2006 and if the trend continues, coral cover could halve again by 2022, with the southern and central areas most affected.

Between 1985 and 2012, coral cover of the reef area fell from 28 percent to 13.8 percent.

"Coral cover on the reef is consistently declining, and without intervention, it will likely fall to 5 to 10 percent within the next 10 years," say the researchers in the study published in the Proceedings of the National Academy of Sciences journal. They called for tougher curbs on greenhouse gas emissions as a crucial way to stem the loss.

Shipping and new ports on the Queensland coast are another major threat, Greenpeace says.

Coal is one of Australia's top export earners and the state of Queensland is the country's largest coal-producer. It also has a rapidly growing coal-seam gas industry for LNG exports.

Earlier this year, Greenpeace estimated port expansion could more than triple Queensland's coal export capacity by 2020 from 257 million tonnes now. That would mean as many as 10,000 coal ships per year could make their way through the Great Barrier Reef area by 2020, up 480 percent from 1,722 ships in 2011, according to the group.

The Queensland and national governments, which jointly manage the reef, have launched a major review of managing the risks facing the UNESCO-listed reef and its surrounding marine area. The review will look at managing the threats from increased shipping to urban development.

Gunn said better management was all about buying time and improving the reef's resilience to climate change. A key area was improving water quality from rivers flowing into the reef area, with studies suggesting fertiliser-rich waters help the crown-of-thorns starfish larvae rapidly multiply. (Editing by Jeremy Laurence)

Half of Great Barrier Reef Lost in Past 3 Decades
Katharine Gammon LiveScience.com Yahoo News 2 Oct 12;

Australia's Great Barrier Reef is a glittering gem — the world's largest coral reef ecosystem — chock-full of diverse marine life. But new research shows it is also in steep decline, with half of the reef vanishing in the past 27 years.

Katharina Fabricius, a coral reef ecologist at the Australian Institute of Marine Science and study co-author, told LiveScience that she has been diving and working on the reef since 1988 — and has watched the decline. "I hear of the changes anecdotally, but this is the first long-term look at the overall status of the reef. There are still a lot of fish, and you can see giant clams, but not the same color and diversity as in the past."

To get their data, Fabricius and her colleagues surveyed 214 different reefs around the Great Barrier Reef, compiling information from 2,258 surveys to determine the rate of decline between 1985 and 2012. They estimated the coral cover, or the amount of the seafloor covered with living coral.

That overall 50-percent decline, they estimate, is a yearly loss of about 3.4 percent of the reef. [Photos of Great Barrier Reef Through Time]

They did find some local differences, with the relatively pristine northern region showing no decline over the past two decades.

Cyclones and starfish

The reef’s decline, detailed this week in the Proceedings of the National Academy of Sciences, can be chalked up to several factors, they found. The biggest factors are smashing from tropical cyclones, crown-of-thorns starfish that eat coral and are boosted by nutrient runoff from agriculture, and coral bleaching from high-temperatures, which are rising due to climate change. (Coral bleaching happens when ocean temperatures rise and cause the corals to expel their zooxanthellae — the tiny photosynthetic algae that live in the coral's tissues.)

Other coral experts say the precipitous decline matches what they have found. "This is a really grim wake-up call," said John Bruno, a biologist at UNC Chapel Hill. "The GBR [Great Barrier Reef], which only 10 years ago was considered the world's most pristine and resilient coral reef is clearly not better off and no less threatened than any other reef. I am bullish on the long-term survival of reefs, but science like this is challenging that outlook."

Saving the reef

As for what can be done to save the reef, or what's left of it, some say reducing carbon dioxide (CO2) emissions is key. "International efforts to cap and reduce CO2 emissions are equally critical and must occur at the same time as cleaning up local impacts," said Les Kaufman, a biologist at Boston University who is part of an international consensus statement on climate change and coral reefs.

Fabricius says not much can be done in the short term about the climate-change-driven frequency of cyclones — five category 5 storms in the past seven years have pounded the reefs — or high temperatures. However, there are efforts in place to stem the damage from starfish, which can grow up to 3 feet (0.9 meters) in diameter and sport long venomous spines and 21 arms. Young starfish feed on coral-making algae, and leave behind the coral's skeleton.

One project encourages farmers to adopt practices that limit the amount of nutrient-rich runoff draining into reef areas. Another would allow tour operators to manually remove starfish from tourist areas, which Fabricius admits isn't a solution, just a temporary fix.

Another option is to examine ways of harnessing natural starfish diseases that typically keep starfish numbers low. "Starfish normally are rare," Fabricius said. "We want to help Mother Nature keep them rare." The research shows that the reef could rebuild itself in 20-30 years despite the cyclones and bleaching, if the starfish population died back.

The experts agree that doing nothing is not an option at this point. "The problem is entirely soluble, and coral reefs can be saved through concerted effort over this and the following two or three generations," said Kaufman. "There is absolutely no excuse for failure to do this, and if we do fail our generation will forever be remembered for unimaginable, unforgivable stupidity and sloth."