UPDATE 7pm: QUEENSLAND Environment Minister Dr Steven Miles has declared action must be taken to protect the Great Barrier Reef from further damage, after increasing levels of coral bleaching prompted an increase in monitoring from today.
Dr Miles said that while the Reef remained a natural wonder and continued to attract millions of tourists to Queensland each year, today's reports of a growing number of coral bleaching outbreaks were a call to action.
He said the "patchy' bleaching - which had prompted authorities and researchers to step up in-water field surveys and monitoring of the reef - had been detected on multiple reefs.
"This is clear evidence that we must aim for a rapid reduction in carbon emissions to reduce global warming," Dr Miles said.
"The natural beauty of the Reef is a drawcard for Queensland and an important ecosystem.
"If these bleaching events become too frequent and intense, it will become very difficult for the Reef to recover.
He said the current bleaching has been found in reefs in mainly shallow areas where corals are frequently exposed to high levels of sunlight.
"Corals get their food from tiny symbiotic algae that live in their cells and provide abundant energy from sunlight," he said.
"When the corals are stressed by events like elevated sea temperatures, they expel the algae and turn pure white as they bleach and their tissues lose the brown cells."
Dr Miles said the Palaszczuk Government was serious about protecting the Reef.
"The Great Barrier Reef is very important to our environment, supports well over 60,000 jobs and is worth $6 billion to our economy," he said.
"The Palaszczuk Government is focused on protecting the reef for the future of our environment and for the future of Queensland tourism.
"That's why we committed $100 million to protect the reef over the next five years."
The Great Barrier Reef Marine Park Authority this afternoon provided the coral bleaching update, announcing the widespread minor bleaching and adverse weather forecasts had prompted the agency to mount a level-one incident response.
Sea surface temperatures are fluctuating across the 345,000 square kilometre Marine Park, but in some areas they've ranged up to 2.5 degrees above the summer average.
GBRMPA will be stepping-up in-water site inspections with its partners with forecasts showing further above average sea surface temperatures were on their way.
Forecasts from the Bureau of Meteorology and the National Oceanic and Atmospheric Administration show a high probability of heat stress which could cause further bleaching.
"The next few weeks will be critical in terms of this bleaching event,'' Dr Miles said.
"I am crossing my fingers that we will not see any broad-scale bleaching events like those that endangered the Reef in 1998 and 2002, and an intense event in the southern part of the Reef in 2006.
"Actions we are taking as part of the Great Barrier Reef long-term sustainability plan will better improve the reef's resilience to these kinds of warming events,'' he said.
Rangers and Great Barrier Reef Marine Park Authority (GBRMPA) staff are constantly monitoring reef health at hundreds of sites across the Great Barrier Reef.
So far this summer, the GBRMPA has contributed towards the more than 514 surveys on 60 reefs, with 57 percent being in far northern and Cairns-Cooktown areas, target reefs with ongoing outbreaks of crown of thorns starfish.
In 19 percent of the surveys they saw coral bleaching, mostly low impact - the affected corals were in the reef flat, or were corals that are highly sensitive to bleaching.
On two surveys, moderate bleaching that affected corals beyond the reef flat, or corals that are usually resistant to bleaching, was reported, also some coral mortality from severe bleaching within the reef flat. In the southern Great Barrier Reef there have been some informal reports of bleaching.
Eleven percent of surveys found coral disease, especially brown band disease. Overall though, no significant coral bleaching or disease has been observed since the beginning of summer.
Further reef health impact surveys are programmed through March and April to inform organisations and government about the health of the reef.
The Eye on the Reef citizen science program means there are even more eyes out for bleaching events.
EARLIER 4:30pm: A GROWING number of reports of coral bleaching in the Great Barrier Reef has prompted authorities and researchers to step up in-water field surveys and monitoring.
Patchy bleaching has been detected on multiple reefs in mainly shallow areas where corals are frequently exposed to high levels of sunlight.
Great Barrier Reef Marine Park Authority Chairman Dr Russell Reichelt said February and March represent the highest risk periods for mass coral bleaching on the Reef because of hot and dry conditions associated with the El Niño weather system and high sea surface temperatures usually present at this time of year.
"Bleaching is a clear signal that living corals are under physiological stress. If that stress is bad enough for long enough, the corals can die. Corals generally have a temperature limit, and the bleaching indicates they're outside of their comfort zone," Dr Reichelt said.
"At this stage, there appears to be low rates of coral mortality restricted to a small number of reefs, and most of the corals affected by bleaching are those that are particularly vulnerable to this type of event such as plate and branching corals.
"Sea surface temperatures are fluctuating across the 345,000 square kilometres of Marine Park, but in some areas they've ranged up to 2.5 degrees above the average for summer. This has been exacerabated by lack of cloud cover.
"Fortunately, what we're seeing right now on the Great Barrier Reef is much less severe than what's happened across the Pacific during the current global bleaching event."
Dr Reichelt said the widespread minor bleaching and adverse weather forecasts had prompted the agency to mount a level one incident response.
"What this means is that we're stepping up in-water site inspections with our partners because the forecasts show further above average sea surface temperatures are on their way, meaning the next few weeks will be critical," he said.
"Forecasts from the Bureau of Meteorology and the National Oceanic and Atmospheric Administration show a high probability of heat stress that would be sufficient to cause further bleaching.
"What happens now will be entirely dependent on local weather conditions. If we're fortunate enough to receive plenty of cloud cover, which will effectively provide shade, it will go a long way to reducing heat absorption by the ocean and alleviating thermal stress on corals."
If mass bleaching does occur, the Great Barrier Reef Marine Park Authority will work with leading science groups to study its extent and impacts. Australian coral reef scientists are combining the skills from the Australian Institute of Marine Science, James Cook University and its Coral Reef Centre of Excellence, the University of Queensland and the CSIRO.
Past bleaching events show coral reefs can recover if the thermal stress does not persist for prolonged periods.
Bleaching occurs when stress causes corals to expel tiny marine algae called zooxanthellae, which live inside their tissue and provide corals with much of their food and colour.
Without zooxanthellae, the coral tissue appears transparent, revealing the coral's bright white skeleton.
The Australian Government is working to improve the Great Barrier Reef's health and resilience so it's better able to withstand threats to its future.
The Reef 2050 plan provides an overarching framework for Reef management and includes a Reef Trust, which will use government and private funds to improve water quality and coastal habitats, and continued work to cull the crown-of-thorns starfish.
The Australian Marine Conservation Society (AMCS) today called on the Federal and State Governments to do their utmost to protect the Great Barrier Reef from global warming and coral bleaching by making a rapid and urgent shift to clean renewable energy.
Imogen Zethoven Great Barrier Reef campaign director for AMCS said coral bleaching has now been found throughout the length and breadth of the Reef.
Although the bleaching is not yet severe, the next 2-3 weeks are going to be critical.
"Coral bleaching is becoming an increasingly dire problem for coral reefs around the world. We have seen severe bleaching followed by a Category 5 cyclone in Fiji in the last month. Those reefs will have suffered severe damage and probably significant mortality," she said.
"Reefs in Hawaii have also bleached severely, in what is now considered a global mass coral bleaching event.
"It is critical that we recognise why reefs around the world, including our own Great Barrier Reef, are suffering bleaching. The reason is that the ocean is warming as a response to global warming, and the leading contributor to global warming is the mining and burning of coal.
"Right now, we are on the verge of a potentially severe coral bleaching event. We hope this doesn't happen.
"The waters of the world have warmed, and coral is the first in the line of global warming's fire. We've seen outbreaks of coral bleaching in the past on the Reef.
"The tourism industry faces a huge crisis if we do not address the causes of global warming. Tourism in Queensland relies on a healthy Reef. It provides 70,000 jobs and billions to the State's economy."
GetUp! has denounced fossil fuel companies for their role in fuelling global warming after the announcement today by the Great Barrier Reef Marine Park Authority that the Reef is experiencing widespread bleaching.
GBRMPA announced the dreadful news that there is widespread coral bleaching throughout the Great Barrier Reef, from Lizard Island in the North, right through to the Southern Reef.
"According to GBRMPA the next few weeks are critical and could see bleaching worsen," GetUp campaigner Ellen Roberts said.
"Today's announcement is distressing for all Australians, and particularly for those Queenslanders who rely on a healthy Reef for their livelihood.
"The mining and burning of coal is driving global warming, which causes coral bleaching. Coal companies are fueling the destruction of the Reef and our government is paying for them to do it.
"We simply can't have both coal and a healthy Great Barrier Reef.
"To stop the Great Barrier Reef being ruined, we urgently need to transition to 100% renewable power. We have the technology but are held back by the polluting interests who dominate Australian politics.
"We're seeing the impacts of global warming happen before our eyes. The majority of Australians want action to stop global warming, and will vote on it at the next election.
"Hundreds of thousands of GetUp members across Australia have taken action to protect the Great Barrier Reef. It's time now for Turnbull to do his part."
"If we want a sustainable tourism industry and a healthy Reef, we will have to urgently cut pollution caused by mining and burning coal.
"The only way we can protect Queensland's biggest tourism attraction is to stop approving new coal mines, stop the Abbot Point coal port expansion and end fossil fuel subsidies and to start to invest in renewable energy as if the Reef depended on it, because it does.".
Update your news preferences and get the latest news delivered to your inbox.