Ancient corals expose human impact on reef

Coral samples dating back thousands of years show evidence of the human impact on the Great Barrier Reef, researchers say.

University of Queensland Professor Gregg Webb said coral "cores" taken from along the Queensland coastline showed definable difference in trace element chemistry, including those linked to European arrival in Australia.

"We can look at ancient events where they're been stressed by bad water, high nutrients, but also just sediment load and see what killed them, what was sub-lethal, how common events are, and just get an idea of what the reef can handle," he said on Tuesday.