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Fish food from flows

Scientists have found an increase in food to support all river life was created by a recent water for the environment flow which inundated wetlands before returning to the River Murray.
Published: 30 November 2021

In Spring 2020 a system-scale environmental flow event was coordinated by New South Wales, Victorian, and South Australian governments, the MDBA and Commonwealth Environmental Water Office (CEWO). During this event – known as the 2020 Southern Spring Flow – water for the environment was added to flows in the River Murray to help provide food and habitat for fish and other aquatic animals.

Scientists used a new method of measuring the metabolism of the water to assess the effectiveness in improving the productivity of the River Murray following a water for the environment flow event. Photo: CSIRO
Scientists used a new method of measuring the metabolism of the water to assess the effectiveness in improving the productivity of the River Murray following a water for the environment flow event. Photo: CSIRO

The 2020 Southern Spring Flow event delivered water to major wetland sites through thousands of kilometres of rivers. Scientists measured changes in productivity along the length of the river to understand whether the spring flows boosted the aquatic food web.

The water from these flows inundated around 25% of Barmah–Millewa Forest before returning to the River Murray. This combined with flows from the Goulburn, Murrumbidgee and Lower Darling (Baaka) Rivers to create a flow pulse down the length of the River Murray from Yarrawonga to the Coorong in South Australia.

The CSIRO measured how carbon, nutrients and stream metabolism changed at 7 key areas along the River Murray in response to the flows. This is the first time the stream metabolism method has been applied to these areas. The measured increases in carbon, nutrients and changes in stream metabolism demonstrated a boost in productivity to support aquatic food webs from the delivery of water for the environment.

This month we published the technical report: Monitoring productivity outcomes of the Southern Spring Flow 2020 – carbon, nutrients and stream metabolism.

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