Robyn Watts

Robyn Watts

Robyn Watts, Australia

Robyn Watts is a Professor of Environmental Science in the Institute for Land, Water and Society at Charles Sturt University, Australia. She undertakes research on the ecology, biodiversity, management and restoration of aquatic ecosystems. Specific areas of expertise include flow-ecology relationships, river rehabilitation through the modification of the operation of dams, and ecosystem responses to environmental flows. She has considerable experience in leading interdisciplinary research teams on projects related to environmental flows. She is interested in bringing together expert and local knowledge to contribute to the adaptive management of water.

Presentation Title:

Widespread flooding in south-eastern Australia in 2016 resulted in a hypoxic (low dissolved oxygen, DO) blackwater (high dissolved organic carbon) event affecting a large area of the southern Murray-Darling Basin. There was concern that prolonged low DO would result in death of aquatic fauna, as a similar event in 2010 resulted in widespread fish deaths. Australian federal and state governments and local stakeholders collaborated to create refuge areas by releasing environmental flows with higher DO and lower DOC from irrigation canals via regulating structures – irrigation canal escapes – into rivers in the Edward-Wakool system. In addition, a group of local citizens installed borrowed and homemade aerators in an attempt to create small fish refuges by temporarily raising the DO. We evaluated water chemistry results from river reaches upstream and downstream of the escapes through which the environmental flows were delivered, fish assemblage and movement data collected before and after the event, and observations from fisheries officers and local citizens of fish deaths during the event, and reports of fish caught after the event. Although many fish deaths were reported during the hypoxic blackwater event, the environmental flows had some positive outcomes. The mean DO increased by 1 to 2 mgL-1 downstream of the environmental flow delivery sites. Fish monitoring results and catch records of recreational fishers showed that live Murray cod were present in the reach of the Edward River that received an environmental flow, but were absent further downstream where there was no environmental flow. The effectiveness of the aerators in raising DO levels was not definitively established, however fish, turtles and crustaceans were observed in close proximity to the aerators. This study demonstrates that environmental flows in conjunction with local landholder ingenuity can create local refuges to help mitigate adverse outcomes during extreme events.

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