Australia's Great Barrier Reef Marine Park Authority said flooding is a 'natural occurrence and corals have recovered from such incidents before,' but some researchers fear the severity of the recent rainstorms is unusual and that the retreating floodwaters could carry pesticides and toxins out into the Coral Sea and damage the reef. (Canadian Press)

Australia's Great Barrier Reef is threatened by pollution and toxic substances being carried out to sea by the devastating floods that have been causing havoc in the eastern state of Queensland for the past few weeks.

Researchers at James Cook's University are concerned that as floodwaters empty into the Coral Sea on Australia's eastern coast, they will bring with them pesticides, heavy metal residue and other toxins washed away from farms and abandoned mines.

"The combined impacts of fresh water, higher temperatures, high nutrients and sediments can stress the corals, particularly those in shallow water," warned Michelle Devlin, a scientist at the university's Centre for Tropical Freshwater Research, in a statement issued by the Great Barrier Reef Marine Park Authority Tuesday.

These foreign substances can compromise the delicate ecological balance of the reef.

"Because coral animals derive most of their food through the photosynthesis that takes place from microscopic algae living in their tissue, corals need warm, clear water to survive," said Rick MacPherson, conservation program director for the Coral Reef Alliance in a statement emailed to CBC News.

Unfortunately, the sediment plumes could have a direct impact on the quality of water and, consequently, on the local marine life.

"Coral larvae need clean, sediment-free surfaces upon which to settle and begin building new coral colonies," MacPherson said.

Climate change intensified rains

The plumes remain relatively contained for the time being. However, depending on weather patterns and water currents, they could spread and potentially cause damage on a larger scale.

In an official statement, the Great Barrier Reef Marine Park Authority remained optimistic, stating that flooding is a "natural occurrence and corals have recovered from such incidents before."

Despite this, MacPherson believes there is a larger issue at stake.

"This is not just a typical rainy season, but a catastrophic storm … there are clear linkages of the increased severity of storms to global climate changes," he said.

"Climate change has likely intensified the monsoon rains."

The Great Barrier Reef stretches over 3,000 km along Australia's eastern coast and is home to thousands of species that are exclusive to its waters.

Around two million people visit the UNESCO world heritage site each year, and recent figures estimate its overall economic contribution to be about $5.3 billion.