Understanding the energy sources of top predators in degraded rivers

Over the last century the flow regimes of Australia’s rivers have been dramatically altered by water extraction and delivery, primarily for irrigation. These impacts will be further exacerbated by the impacts of climate change. Altered flow regimes have already had substantial impacts on riverine biodiversity, as flow regime is a key driver within river ecosystems.

My PhD seeks to understand the influence of streamflow on river food webs, with a particular focus on the energy sources of significant top consumers. There are significant gaps in understanding of the flow conditions needed to generate food resources for iconic species such as the Murray cod, golden perch, and straw-necked ibis. As freshwater decapods (prawns and shrimp) make up a significant proportion of their diets, this year I plan to research how changes in flow affect decapod abundances and decipher their role in supporting top predators.

I will use stable isotopic signatures to trace how river flow affects food webs in the Lachlan River, NSW. The funding requested this year will enable the acquisition of abundance and food-web role data for decapods, an enigmatic but crucial food web source for large fish and water birds. By providing information to develop food-web simulations, the anticipated outcomes of this research will improve streamflow management and food-web resilience towards current and future flow conditions.