CANBERRA, ACT, July 10 -- Murray-Darling Basin Authority issued the following news release:

The Barwon-Darling River in north-western New South Wales is a dynamic ecosystem that is constantly changing.

The river experiences several distinct phases, including:

* base flow, low flow or cease-to-flow periods where dry conditions cause water flow to be minimal or stop entirely. * flowing freshes and bankfull flows, where the channel is connected by flowing water following rainfall events * overbank flooding, as large volumes of rainwater enter the system and floods nearby areas, floodplains and wetlands.

While low flow in rivers may appear concerning, many species have adapted to low flow conditions. Periods of low flows are a natural occurrence in the Barwon-Darling River but have increased due to historic water resource development and water management. Some fish and freshwater mussels prefer to reproduce in the stable water low flows provide. Low flows are also vital for zooplankton - small animals that cannot swim well and rely on water currents to move around.

The changing climate is causing more frequent and prolonged low flow conditions in the Barwon-Darling River. This is placing stress on river organisms and they can struggle to adapt. It has also contributed to mass fish kills throughout the river.

A recent Murray-Darling Water and Environment Research Program (MD-WERP) project looked at the history and impacts of low flows in the Barwon-Darling River. It also looked at the diversity of wildlife to understand how changing flow conditions affected different species.

Researchers found that small-bodied fish (e.g. olive perchlet) were among the most impacted by increasing low flow events. Low flows limit the number of habitats available for these fish and reduces breeding. Animals that can't move well, like prawns and freshwater mussels, are also particularly vulnerable as they can't move to nearby areas with remaining water.

It is critical we understand the history of low flow events in the rivers of the Murray-Darling Basin and how they are changing. This project highlights the importance of maintaining refugial habitats and managing water to mimic natural flow phases to support vulnerable organisms in the Barwon-Darling River.



This research was supported through funding from the Australian Government Murray-Darling Water and Environment Research Program.



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