Great Barrier Reef: no buried treasure

08 February 2002

Scientists at Geoscience Australia have found that the northern end of the Great Barrier Reef, one of the great treasures of the world, is safe from sediment that is naturally discharging from the mouth of the Fly River in Papua New Guinea.

They have discovered a zone of strong tidal currents which prevents the southward advance of sediment that would otherwise gradually bury the northern-most coral reefs.

The mouth of the Fly River is located close to the northern end of the Great Barrier Reef and carries 120 million tonnes of sediment per year - more than the combined amount of sediment carried by all of Australia's rivers.

Using underwater video equipment and a sophisticated mapping technique, the Geoscience Australia team has found a series of scoured channels which extends for more than 80 kilometres through the seabed from eastern Torres Strait across the northern end of the Great Barrier Reef. The channels are up to roughly 170 metres deep.

The channels act as a conduit, allowing cool, nutrient-rich water to upwell from the Coral Sea, located to the south-east of the river mouth. The Coral Sea hosts the mighty Great Barrier Reef.

The findings are part of a research expedition led by Geoscience Australia's Dr Peter Harris, to track the river's influence by mapping the local seabed and sampling its sediment. The research team also includes scientists from James Cook University, University of Sydney, University of Tasmania and the CSIRO.

The team returns from its cruise shortly, arriving in Cairns at 1 p.m. on Saturday 9 February in the vessel RV Franklin.

The mouth of the Fly River is approximately 300 kilometres north of the tip of Cape York Peninsula.

The Great Barrier Reef is the biggest single structure made by living organisms and is large enough to be viewed from outer space.

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