Slowdown after Ice Age sounds a warning for Great Barrier Reef's future

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

University of Sydney research shows that environmental factors similar to those affecting the present day Great Barrier Reef have been linked to a major slowdown in its growth eight thousand years ago.

Lead author Belinda Dechnik said that poor water quality, increased sediments and nutrients, conditions increasingly being faced by the modern day reef, caused a delay in the Reef's growth of between seven hundred and two thousand years duration.

Dechnik added that it took hundreds more years then they would have expected to establish itself and even longer to attain the complex level of biodiversity that much of the Reef has become famous for.

While that may appear inconsequential in the 700,000 year history of the Reef even a decade of such delayed growth would have a rapid impact on today's Reef and the experiences of the estimated two million people who visit it every year, Dechnik added.

The researchers sampled 15 reef cores from the Southern Great Barrier Reef. The cores were radiocarbon dated to establish their ages. Species of reef corals were also identified to establish any coral community changes over the past eight thousand years.

The findings show that when the Great Barrier Reef started its current regrowth, following the sea level rise when the ice sheets last melted eight thousand years ago; it was acutely sensitive to the turbulent conditions.

The increase in sediments and nutrients following the flooding of the pre-existing reefs is likely to have been responsible for the poor water quality.

The study is published in Marine Geology.