Turbid floodwaters flowing into the Great Barrier Reef may cause an explosion in algal blooms and more coral bleaching, authorities warn.
The Fitzroy, Burnett and Thompson rivers have flushed floodwaters into the reef's inshore areas, particularly off the central Queensland coast near Rockhampton.
The Great Barrier Reef Marine Park Authority (GBRMPA) is mapping the plumes of muddy water and taking samples for testing.
So far, it is not affecting popular tourism locations in the Whitsundays, Cairns or Port Douglas area.
The samples are being tested for pesticides, salinity, turbidity and temperature.
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GBRMPA spokesman Andrew Skeat said it would be some time before the extent of the damage would be known.
He said the flood run-off, full of sediment and nutrients, could spark increased algal blooms, coral bleaching and coral diseases.
"Even when ecosystems are exposed to freshwater plumes they do not necessarily die," Mr Skeat said.
"Many plants and animals have mechanisms to cope ... however, this event has unusually large amounts of flood run-off with suspended material and the prevailing conditions may be different to previous events."
He said it could also increase the productivity of some inshore species such as barramundi, mangrove jack, some prawns and sponges.
