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Floods could impact Great Barrier Reef

G-Online

The recent Queensland floods could smother parts of the Great Barrier Reef with sediments, pesticides and fertilisers.

anemone

Delicate anemones such as these in the southern region of the Great Barrier Reef are threatened by freshwater and sediments from the Queensland floods.

Credit: Image courtesy of John Johnstone.

Nudibranch

This gorgeous nudibranch was photographed in the southern part of the Great Barrier Reef - it is threatened by freshwater and sediments from the Queensland floods.

Credit: Image courtesy of John Johnstone.

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Runoff from the extensive floods in Queensland is expected to impact heavily on the southern parts of the Great Barrier Reef, by coating it with great amounts of sediment and agricultural chemicals.

The Burdekin and Fitzroy Rivers have already dumped sediments around the Keppel Islands and the Capricorn Coast respectively.

"Our work has shown that high levels of nutrients and sediments can reduce coral diversity and increase the cover of seaweeds on inshore reefs," Katharina Fabricius, a researcher at the Australian Institute of Marine Science (AIMS), told msnbc.com.

Three million tons of sediment coats the Great Barrier Reef every year. Mostly, this is made-up of topsoil eroded by grazing cattle along unfenced waterways. While corals can naturally cope with some flushes of freshwater and sediments, the current flooding is also made-up of a cocktail of agricultural runoff that the corals are unlikely to have encountered before, such as potentially deadly artificial pesticides and fertilisers.

Alison Jones from CQ University described the devastating effect of the 1991 floods to ABC Online: "The 1991 flood was extremely hard for the reef - pretty much most of the corals were wiped out down to about six to eight metres of depth and it took about ten years for them to recover but they recovered magnificently," said Jones. "We're very spoiled here in terms of the amount of coral and the speed at which it can grow and recover."

Jones explains how high tides will help to flush the reef. "The corals will have fresh water on them and then they'll have salt water on them - fresh, salt, fresh, salt - which they can survive a lot better than just having fresh water surrounding them all the time," she told ABC Online.

Next week, a team of AIMS scientists will conduct a research trip to the Great Barrier Reef to assess the impacts of the flooding.