Australian news, and some related international items

Crisis in Australia’s one great river system: climate change a factor

Drought, climate change and mismanagement’: What experts think caused the death of a million Menindee fish, ABC Science, By environment reporter Nick Kilvert, – 16 Jan 19


The sight of more than a million fish floating belly up on the Darling River at Menindee has thrown doubt over the management of the Murray-Darling Basin.

Experts say irrigators are taking too much water from the system, and the Murray-Darling Basin Authority has mismanaged water flows.

But New South Wales Water Minister Niall Blair says drought is to blame.

With more fish likely to die, here’s what we know about the mass deaths and what some independent experts have had to say.

Where are fish dying?

A million fish were found dead at Menindee Lakes last week.

It’s a series of seven lakes fed by the Darling River, about 90 kilometres south-east of Broken Hill in western New South Wales. It’s believed to be one of the largest fish kills ever recorded in Australia.

Then a smaller kill of about 60 fish was reported at Lake Hume yesterday, on the NSW-Victoria border.But the cause of that kill is still unclear.

What killed the fish?

A variety of factors were at play at Menindee. Water levels were very low, the system had stopped flowing, and temperatures were high after a long spell of hot weather.

This created ideal conditions for blue-green algae (cyanobacteria) to grow, and it “bloomed” out of control.

But it wasn’t the algae that killed the fish.

A cold front hit the region, which dropped the water temperature in the river, killing the algal bloom.

The bacteria that feeds on dying algae then exploded out of control, and sucked all the oxygen from the water.

When the oxygen levels dropped too low, the fish drowned.

So who or what is to blame?

The blame game began almost immediately after the Menindee fish kill was reported.

January 17, 2019 - Posted by | AUSTRALIA - NATIONAL, climate change - global warming

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