Environmental flow rules in river tributaries boost productivity in the Barwon-Darling (Barka) River

In collaboration with the University of Technology, Sydney, we investigated how the Mehi and Namoi tributaries of the Barwon-Darling (Barka) River maintain connectivity and benefit productivity. In addition to directly measuring the essential food resources from the tributaries, we used an experimental approach to mimic tributary flow events of different magnitudes.

Tributaries were more productive than the Barwon-Darling River and flow events from these tributaries provided additional food resources such as nutrients and organic matter to the main-stem river and helped stimulate basal food web productivity (e.g. phytoplankton, bacteria and zooplankton). The tributary inflows provided greater resource diversity within the river and reduced the dominance of algae as a food source. This process helps promote a healthier river ecosystem that benefits native fish such as Murray Cod and waterbirds, and can also maintain and improve water quality.