ALMOST $50 million went into three environmental groups behind the Fight for the Reef campaign in the past 18 months.
Large 'sugar daddy' contributions from private foundations bolstered thousands of smaller donations.
WWF Australia, Greenpeace Australia-Pacific and the Australian Marine Conservation Society funds were documented in each group's filings with the national charities regulator, covering the past 18 months.
They reveal WWF received the lion's share of funding in the 2013-14 fiscal year, at $29 million. Greenpeace raised more than $19 million and the AMCS received $1.3 million in calendar 2014.
Each group cited Sunshine Coast-based conservation group The Thomas Foundation as a key source of funds, but none would comment on other significant backers.
University of Queensland political expert Graeme Orr called such groups the "sugar daddies" of the green movement. While general donations also went to other campaigns and on-ground programs, from shark conservation and marine park programs to plastic bag campaigns, much went on education, PR campaigns and advocacy.
Professor Orr said that while business groups often used "heavy duty lobbying" to influence government policy, environmental groups largely relied on a combination of thousands of small donations from the public and a few sugar daddies, such as The Thomas Foundation.
He said the rise of third-party issues campaigns was more like a "leapfrogging race" than an arms race, but that once one side did it, the other side was "almost expected" to follow with similar tactics.
Despite being the only one of the three green groups to file a third party return of political expenditure with the Australian Electoral Commission, WWF Australia chief Dermot O'Gorman denied the group was involved in "political advocacy".
"We don't undertake any political activity - we undertake campaigns on issues which we are very passionate about and we maintain very transparent operations," he said.
Mr O'Gorman confirmed the group received more than $1.3 million that had to be declared on the form, but that only a "proportion" of those funds went to the Fight for the Reef campaigns.
"We have to declare the full donations, but only a very small proportion of that was used on educational material during the (2013) election," he said.
He did confirm most of the Pace Foundation's $500,000 donation went to "communicating the importance of climate change" to the public, and was fully declared.
In contrast, Greenpeace chief David Ritter said he was "extremely proud" of the campaigning work his group completed, confirming the Fight for the Reef campaign was "our single largest piece of work" in the past three years.
"For example there's work being done on this by offices around the world, and like any global organisation, we have to manage that as efficiently as possible," he said.
While Greenpeace worked on various other causes, including climate change and container deposit schemes, it spent 57% or at least $9 million of its total spending on campaigns primarily on Fight for the Reef.
Similarly, financial documents show WWF Australia raised $23 million in donations, major gifts, legacies and bequests, about $422,000 in government funds and $3 million in corporate contributions, mostly for sustainable industry certification partnerships.
Mr O'Gorman said WWF had no direct involvement with court cases lodged against coal-related projects in Queensland.
"We have from time to time promoted their causes, but not directly," he said.
AMCS also put some $967,000 in project-related funding in 2013/14 towards the reef campaign, as well as other smaller projects on marine national parks, shark conservation and threatened species conservation.
But AMCS chief executive Darren Kindleysides said political advocacy and legal action against major projects had long been an important part of all environmental work on the reef, going back to the 1960s campaigns to stop oil drilling.
"Without advocacy, there would be little impact from on-ground work," he said.
"Really, our work has been around building awareness in the general public and community groups."
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A look behind the scenes at who finances what you read, see and hear about the reef
LARGE "sugar daddy" donors and mining companies were among those bankrolling Great Barrier Reef public relations campaigns in recent years.
High flyers with links to the very industry that conservationists say threatens the future of the reef have a real say over how research funds related to climate change and the reef are being spent.
This is the first in a three-part series where APN Newsdesk will unravel the millions of dollars behind the campaigns that end up on your televisions, newspapers and other media.
This comes as a federal committee examines political advocacy and tax deductible donations for environmental groups - an inquiry labelled as a witch-hunt designed to stifle community debate.
Newsdesk's Daniel Burdon examines the finances behind the national, state and local green groups, mining lobby groups and a private foundation crossing the divide between miners, government and scientists.
Read more about reef finances Wednesday and Thursday.