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Murray Trickles Into World's Bottom 10 Rivers


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Murray trickles into world's bottom 10 rivers

THE Murray-Darling river system is one of the world's 10 most endangered because governments have failed to protect it from invasive fish and plant species, WWF International says.

Dramatic changes in the flow of water and failure to control or kill exotic species have put huge pressure on native fish such as the silver perch and large Murray cod, while invasive European carp and plague minnow have flourished.

The Murray, which is one of the world's longest rivers and has one of the biggest catchments, is also threatened by the regulation of its flow by dams and weirs, and by salinisation and climate change.

"When we regulate the flows we make the rivers more suitable as habitat for invasive species," said the freshwater policy manager for WWF Australia, Averil Bones.

Excessive water extraction had led to many of the problems facing the Murray-Darling, but it was not a key threat because of recent government initiatives to change the amount of water used by farmers and irrigators.

The six biggest threats to the world's rivers were dams, excessive water extraction, climate change, invasive species, overfishing and pollution, the report said.

The conservation group picked the 10 large rivers it believed already seriously suffered from these threats or were bracing for the heaviest impacts.

"Even the greatest of the world's rivers can no longer be assured of reaching the sea unhindered," the report said.

One of the biggest problems for the Murray-Darling is the explosion in European carp numbers. They are estimated to account for 60 per cent to 90 per cent of fish in the river, with densities as high as one carp per square metre.

"Since 1990, the number of exotic fish in Australia's waters overall jumped from 22 to 34, and all except for one of these introduced species originated from the aquarium trade," the report said.

Foreign plants, particularly those released from aquariums and ponds, are also a problem, crowding the rivers' banks and choking their courses.

The report named lippia, introduced as an ornamental "no mow" lawn, as an example. "These plants reduce the natural productivity of the floodplain, river and other wetland habitats, further depleting natural wildlife populations," the report said.

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Such a shame to read that. At school we were imparted with a sense of pride for our "Magnificent Murray Darling" What a trerrible state of affairs to learn that the people of government didn't get the same lessons in school.

Edited by Boofhead
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