About This Project

The River Murray system in Murray Darling Basin (MDB) of Southeast Australia contains vast numbers of shallow floodplain lakes. Some of these lakes are clear while the others are turbid despite their close proximity, and connectivity to the river, and exposure to humans. Our project will devise whether benthic cladocerans in these two contrasting floodplain lakes, show signs of differential timing in water quality through their changes in assemblage and diversity in the past?

Ask the Scientists

What is the context of this research?

The shallow Murray River lakes of MDB of Southeast Australia are characteristic to macrophyte rich or phytoplankton dominated system. Macrophyte-dominated lakes are clear and have minimal human impacts, while the phytoplankton-dominated lakes are turbid due to increased catchment disturbances. Fossils of benthic cladocerans are preserved in lake sediment and can reflect past water quality change. Barmah Lake (Victoria) and Pikes Creek (South Australia) show contrasts in stable macrophyte vs stable phytoplankton regime despite their close proximity, and connectivity to the river and are exposed to similar human impacts over the past decades . Using benthic cladocerans, we identify the timing of shifts in lake water quality and compare them between the two lakes.

What is the significance of this project?

In Australia, provision of environmental flows and lake water quality to maintain lake ecosystems have the prime objective of restoring degraded system. However, the condition of many Murray River lakes is unknown and the ecosystems of these lakes are facing critical conservation and management challenges today. The use of benthic cladocerans is increasingly becoming a novel approach to address water quality issues due to preservation of their fossils in lake sediment. A fine-scale detection of change in Barmah Lake (macrophyte-state) and Pikes Creek (phytoplankton-state) exposed to similar human impacts over the past decades will allow us to determine timing of shifts in water quality. This will help inform resource managers to apply appropriate restoration measures.

What are the goals of the project?

There are three goals. Firstly, this project will determine the ability of benthic cladocerans, and the novelty of the use of their fossils to infer long term dynamics of water quality and ecosystem change in two shallow floodplains Murray River lakes in Southeast Australia. Secondly, the diversity and assemblage of fossil benthic cladocerans in sediments will help understand the mechanisms behind the differences in varying ecosystem responses to changes of these floodplain lakes which undergoing similar anthropogenic impacts such as river regulation and catchment nutrient loads in the past. Finally, this project will provide some key recommendations that are applicable to resource managers for conservation and management of degraded Murray River floodplain lakes in Southeast Australia