Dr Keller Kopf, Associate Professor Skye Wassens, and Luke McPhan
Floodplains are critical habitats for native fish. They provide highly productive nursery habitat and food to support reproduction and recruitment. For this project, researchers are evaluating how a managed connection of the Murrumbidgee river with its floodplain influences the food resources available to native and invasive fish.
Since the diet of fish is reflected in isotope and fatty acid concentrations of their tissues, they are using these analyses to identify the food resources supporting fish reproduction, growth and recruitment.
Researchers began monitoring the effects of an environmental water delivery in September 2018, across the floodplain to Tala and Yanga Lakes on the lower Murrumbidgee River. The environmental water delivery was aimed at supporting native fish and waterbirds in the floodplain system. The lakes are also home to other native fauna including freshwater shrimp, frogs, snakes and turtles.
The area had had less than 80 mm of rain since January 2018 and Yanga National Park was one of a few sites selected to receive Commonwealth water for the environment in 2018. During the drought period, it was identified as a priority site that needed protection, to build resilience so that native fish and other wildlife can recover when the dry conditions ease.
Starting in 2018, tissue samples were collected from a range of fish species around the Murray-Darling and analyses of nitrogen and carbon isotopes were used to estimate the trophic position of the fish community. This one year project served as a pilot study to test the feasibility and utility of using a trophic position indicator as a tool for annual monitoring of long-term ecosystem changes in the Murray-Darling.
Kopf R.K., Wassens S., McPhan L., Dyer J., Maguire J., Spencer J., Amos C., Kopf S., Whiterod N. (2019) Native and invasive fish dispersal, spawning and trophic dynamics during a managed river floodplain connection. Commonwealth Environmental Water Office. Murrumbidgee Selected Area Final report, pp 1-49.
The project’s findings will be used in adaptive management actions to guide the timing and magnitude of environmental water delivery connections between river channels and floodplain ecosystems.
Dr R. Keller Kopf