Research shows coral growth 'lag' after high sediment flow

NEW research investigating the effect of the "Big Melt" after the Ice Age could herald concern for the future of the Great Barrier Reef if more dredging projects go ahead.

The University of Sydney research examined 15 reef cores near Gladstone, finding that poor water quality, high turbidity and higher sedimentation after the Ice Age caused a 2000-year halt in coral growth in the region.

PhD student and lead author of the paper, Belinda Dechnik, said while her research examined events thousands of years ago, it was a cause for concern for the future of the reef if sedimentation was to increase.

She said the research showed a delay in coral growth followed the melt, causing mainly corals that could withstand more turbid waters to grow, while most others stopped growing altogether.

"It took hundreds more years than we expected to establish itself (after the melt), and even longer to attain the complex level of biodiversity that much of the reef has become famous for," she said.

"Not only was there a lag in reef growth of up to two thousand years following the flooding of the previous reef platforms but the reef communities that grew there were much less complex than those inhabiting those areas of the reef today.

"It took another two to three thousand years for the rich diversity that we see in those reef areas today to become established."

While Ms Dechnik said the research showed what had happened due to high sediment flows and turbidity thousands of years ago, she said there were no clear findings of how human-influenced development might affect the corals in the future.

"It does have implications for the future of the reef, showing that only some corals can survive under those conditions, but I think the specific influences would be the subject for a whole new PhD," she said.

"But given the effects of higher levels of sediment, turbidity and nutrients on the reef, I do hold some concern for how future dredging projects could affect the corals, but that wasn't part of this study."

The research was published earlier this month in the Marine Geology journal.