Dredging does impact coral reefs, world-first scientific study finds

news.com.au 17 Jul 14;

IN A world-first study, Queensland scientists have shown that dredging impacts are damaging to places like the Great Barrier Reef.

It shows that corals near dredging sites have twice as much disease as other sites.

Dredging made water muddy and eventually led to disease, a major factor in coral diseases, the report found.

The findings are at odds with the campaign run by Environment Minister Andrew Powell to stop UNESCO from listing the Great Barrier Reef World Heritage area in danger.

Citing a 2009 Australian Institute of Marine Science report, Mr Powell has argued that the Reef’s biggest impacts are extreme weather, coral bleaching and crown-of-thorns starfish, not dredging, ports or shipping.

Conservationists have agreed that these issues have a great impact, but say the coal-driven port boom occurred mostly after the 2009 study, and that dredging is another stress that the Reef struggles to handle.

Mr Powell has described conservationists campaigning for better Reef protection as liars. Although half the coral has disappeared, he has said the Reef is ``looking fantastic’’.

AIMS and James Cook University scientists said the study, released this week, was the first to examine the link between dredging and coral disease in the natural environment.

It was conducted near Barrow Island off Western Australia and close to an 18-month, seven-million-cubic-metre dredging project which saw a channel dug for shipping.

Corals died, leaving behind white coral skeletons and it was feared the diseases might linger well after dredging ended.

JCU researcher Joe Pollock said dredging was a pressing issue on the Great Barrier Reef.

Mr Pollock said he was not arguing against dredging, but the need for better management of projects.

He said there was no particular distance that could be set for dredging or spoil dumping from corals because much depended on how far plumes could travel under local conditions.

Mr Powell declined to comment.

Mining Resources Council chief executive Michael Roche said the study showed that impacts of the dredge plume at Barrow were temporary and localised.

Describing the Reef as pristine, he said the research would be studied.

AIMS scientist Britta Schaffelke said turbidity and sedimentation were critical pressures on coral reefs.

``What this study does is highlight a direct link between coral disease and sedimentation and turbidity,’’ Dr Schaffelke said.

Mr Pollock said twice as much disease was found at dredging sites than control sites.

A WWF spokesman said given that turbidity levels were worse in Queensland compared to WA, it meant the impact from dredge plumes here was likely to be worse than in WA.

Originally published as Will Reef come to grief from dredging?