The Great Barrier Reef is home to the world's largest collection of coral reefs, with around 400 types of coral and 1,500 species of fish.
But in recent years, it has lost almost a third of its coral due to bleaching linked to rising sea temperatures and damage from crown-of-thorns starfish.
The funds will go toward combating water pollution, predatory coral-eating starfish, increasing public awareness and reef monitoring, as well as modifying surrounding businesses so that they are more environmentally sound, Turnbull's office said.
Climate change also affected the creatures that live in the reef system. The opposition said the government could still fail to reach its target to reduce emissions 26 to 28 per cent on 2005 levels by 2030.
But the cash splash has been met with criticism from conservationists who have accused the government of not doing enough to address the thing that poses the biggest threat to the reef, climate change.
"We must improve water quality".
A University of Sydney marine biology professor, Maria Byrne, says the funding measures are welcome, especially for those areas of the reef heavily dependent on the tourism market. Crown-of-thorns starfish were responsible for nearly half of this decline.More news: State will pay for repeat smear tests for women, Health Minister confirms
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Turnbull said it was the "largest ever single investment - to protect the reef, secure its viability and the 64,000 jobs that rely on the reef".
The 2016 bleaching event, the worst on record, mainly affected the north of the reef, while the recent damage has mostly impacted the middle sections, according to scientists at the ARC Centre of Excellence for Coral Reef Studies. "Climate change is the number one threat to the Great Barrier Reef and only concerted action to cut pollution will fully protect it".
The government, in a partnership with the Great Barrier Reef Foundation, will contribute $444 million.
"Today's major investment brings real solutions within our grasp".
The Great Barrier Reef provides $6.4 billion a year to the Queensland and Australian economies.
A further $56 million will bolster the Great Barrier Reef Marine Park Authority and Department of Environment and Energy to expand management and compliance operations.
In 2016, Labor also pledged $500 million of funding over five years towards the Reef if elected.