Dredging linked to coral disease: study (AAP)

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Dredge plume from coastal developments can stress coral, making them more prone to chronic diseases, Queensland researchers have found.

Their study compares 11 reefs and thousands of coral near Barrow Island, off Western Australia, where a seven million cubic metre dredging project took place.

Lead author marine scientist Joe Pollock says twice as much coral disease was recorded in areas where dredged sediment had drifted and settled.

Turbidity meant there was less light, and sediment on the coral interfered with their ability to feed.

"Basically they need light and they need food," the James Cook University and Australian Institute of Marine Science PhD student told AAP.

"So they have less energy coming in, they're expending more energy and what we've shown here is that chronic stress can lead to disease."

The most common was white syndrome, a chronic disease which causes coral tissue to fall off.

Mr Pollock says there are many contributing factors to coral disease including climate change, crown of thorn starfish and cyclones.

"But when you add another impact on top of that, there's every reason to believe that will only exacerbate the levels of disease we're already seeing," he said.

He says the study, the first to look at the link between disease and dredging, highlights "knowledge gaps" in what we know about dredging and its potential impacts.

There has been public debate on the potential impacts of dredging, especially on the Great Barrier Reef, since the announcement and subsequent approval of major dredge projects such as Abbot Point coal port near Bowen.

Queensland Resource Council chief executive Michael Roche welcomed the study, but added that it was "essentially a laboratory-style study" that highlighted what was already known.

"That is that the impacts of dredge plume is very temporary and very localised," he said.

Mr Roche said studies had shown the biggest cause of coral disease was the crown of thorn starfish and cyclones.

Mr Pollock agreed that impacts were localised - coral most impacted were within 10km of the WA dredge project.

"But as far as temporary, a lot of these coral diseases that we've seen, especially white syndrome, they can be quite chronic ... and in the long run it's fatal."

The study, Sediment and Turbidity Associated with Offshore Dredging Increase Coral Disease Prevalence on Nearby Reefs, was this week published in the PloS ONE journal.

http://au.news.yahoo.com/a/-/latest/24480033/dredging-linked-to-coral-disease-study/