Ecosystem functions in the Murray-Darling Basin

The challenge

A more holistic approach to managing water-dependent ecosystems

Ecosystem functions are a broad suite of processes essential for maintaining health, structure, and integrity of an ecosystem. Consideration of ecosystem functions and how they relate to water dependent ecosystems and hydrology are critical for holistic water management. In the Murray-Darling Basin, the importance of ecosystem functions is recognised in the Water Act, Basin Plan, the Basin-wide Environmental Watering Strategy, and annual watering priorities. However, traditionally there has been a focus on selected species and key sites rather than a more holistic approach to managing water-dependent ecosystems.

A collaborative project between CSIRO and the Murray Darling Basin Authority, the Ecosystem Functions project addressed key ecosystem functions knowledge gaps at basin-scale to inform improved management and delivery of water for the environment in the Murray-Darling Basin. View the project video below.

1 00:00:23,240 --> 00:00:27,840 Hi, I'm Dr Ashmita Sengupta, I'm a senior research scientist at CSIRO, 

2 00:00:27,840 --> 00:00:31,520 and along with Paul McInerney, I was the project lead for this project. 

3 00:00:31,520 --> 00:00:34,520 Ecosystem functions are processes and activities 

4 00:00:34,520 --> 00:00:38,600 that are essential for maintaining health and integrity of an ecosystem. 

5 00:00:38,600 --> 00:00:42,560 Consideration of all ecosystem functions and how they relate to 

6 00:00:42,560 --> 00:00:46,320 rivers and wetlands are critical for effective water management. 

7 00:00:46,320 --> 00:00:50,160 This was a three year research project, it addressed key knowledge 

8 00:00:50,160 --> 00:00:54,720 gaps at a basin scale needed to inform improved water management 

9 00:00:54,720 --> 00:00:58,480 and delivery of water for the environment within the Murray-Darling Basin. 

10 00:00:58,480 --> 00:01:03,400 And about 24 CSIRO scientists worked on it, through four research themes. 

11 00:01:03,400 --> 00:01:06,880 Several new data sets and models were generated 

12 00:01:06,880 --> 00:01:09,840 at basin scale, spanning over three decades. 

13 00:01:09,840 --> 00:01:11,120 These new data layers 

14 00:01:11,120 --> 00:01:15,200 can support analysis and applications that were not possible before. 

15 00:01:15,200 --> 00:01:17,800 Hi, I'm Dr. Sam Nicol from the CSIRO. 

16 00:01:17,800 --> 00:01:20,240 I led the basin scale biological movement theme 

17 00:01:20,240 --> 00:01:21,800 of the Ecosystem Functions Project. 

18 00:01:21,800 --> 00:01:23,760 In this project we studied water birds and 

19 00:01:23,760 --> 00:01:26,080 We tried to understand what factors are needed to support 

20 00:01:26,080 --> 00:01:27,640 long distance waterbird movements. 

21 00:01:27,640 --> 00:01:31,360 If we understand how far water birds move, we'll be better able to manage 

22 00:01:31,360 --> 00:01:35,280 the landscape and rivers, to make sure that they are around for years to come. 

23 00:01:35,280 --> 00:01:37,880 We have a fantastic satellite tracking dataset 

24 00:01:37,880 --> 00:01:40,880 that enabled us to really explore this question in high detail. 

25 00:01:40,880 --> 00:01:44,560 This data let us know where the birds were every hour while they were in flight. 

26 00:01:44,560 --> 00:01:45,760 This kind of data 

27 00:01:45,760 --> 00:01:47,920 gives us amazing capabilities to explore 

28 00:01:47,920 --> 00:01:49,880 what motivates birds to fly so far, 

29 00:01:49,880 --> 00:01:50,840 which in turn 

30 00:01:50,840 --> 00:01:54,440 helps us to understand what conditions they need to help them flourish. 

31 00:01:54,440 --> 00:01:56,920 So this project has improved our understanding 

32 00:01:56,920 --> 00:02:00,560 of ecosystem functions across the entire Murray-Darling Basin. 

33 00:02:00,560 --> 00:02:04,480 It has provided the tools to inform decision making, river planning, 

34 00:02:04,480 --> 00:02:09,440 management of ecosystem functions across this important Australian waterway. 

35 00:02:09,440 --> 00:02:13,160 The research also helps improve environmental water management. 

36 00:02:13,160 --> 00:02:16,840 Finally, our work has been published in prestigious journals and 

37 00:02:16,840 --> 00:02:20,680 is being used in ongoing, large Australian government funded projects 

38 00:02:20,680 --> 00:02:23,360 that look at water management in the basin.

Through four main themes of research, the Ecosystem Functions project delivered new knowledge in understanding of ecosystem functions in the Basin.

A central focus of the project was to engage with our stakeholders and the scientific community. This was achieved through a series of workshops, the publication of high-profile research papers, and participation in scientific conferences.

Our response

Protecting the environment and the inhabitants of the Murray-Darling Basin

Our research was conducted across four broad ecosystem function themes:

• Hydrological connectivity-several new datasets, including floodplain inundation extent and depth and in-channel water depth and velocity at basin scale, were generated spanning over three decades. These new data layers support analyses and applications that were not possible before, such as determining the volume of water present in the Basin and assessment of historical inundation of different vegetation communities.

• Biological habitat provision-a statistical modelling approach was applied to generate predictions of species occurrence and habitat quality across a time-series of several decades (1995-2020) for the entire Basin. The models developed also identify the important environmental variables for predicting species occurrence and habitat quality over space and time.
• Productivity- the research demonstrated that flow and the connectivity between floodplains and rivers is an important determinant of riverine Dissolved Organic Carbon (DOC) supply. Furthermore, flow and temperature (and season) are important for Riverine Gross Primary Productivity (the amount of carbon fixed during photosynthesis by all producers in the ecosystem) and Ecosystem Respiration.
• Biological connectivity for waterbirds and native fish- this theme focused on quantifying the drivers and likelihood of long-distance, basin-scale movements of waterbirds using straw-necked ibis as a case study species. Statistical modelling indicated that for straw-necked ibis wind strength and direction are primary factors determining the distance travelled during long-distance movements, more so than season. Understanding the role and importance of wind conditions for long-distance waterbird movements is useful knowledge for managers that can be used to enhance movement opportunities through the strategic use of environmental water. In addition, river regulation in the Basin has altered the hydrology and hydraulics of rivers, and created barriers that impede fish movement along rivers (longitudinal connectivity) and onto the floodplain (lateral connectivity). A modelling approach to integrate native fish movement characteristics with improved knowledge of instream barriers and hydraulics was applied at the basin scale. Understanding the impact of barriers on fish movement is crucial for management of fish passage, environmental flows, and for supporting management decisions and the need for intervention.

The results

Addressing knowledge gaps and gaining a deeper understanding of the importance of ecosystem functions

The targeted outcomes of this work were:

• Improved capacity to understand functions of water-dependent ecosystems
• Improved science and tools to inform decision-making, river planning and management of ecosystem functions across the Basin
• Improved ability to communicate to the Australian public, the importance of ecosystem functions and their management.

The project addressed several knowledge gaps that have improved our understanding of ecosystem functions within the entire Basin. It delivered new products not available prior, such as floodplain inundation extent and depth estimation at bi-monthly time steps, long-term habitat mapping for vegetation, waterbirds and fish, and waterbird movement modelling and prediction. The research has built causal relationships between ecosystem functions and flow/connectivity which is imperative to inform improved environmental water management focussing on ecosystem functions. Furthermore, modelling outputs generated from the hydrological connectivity theme are being used and extended by Australian Government funded projects including the Flow Monitoring, Evaluation and Research (FLOW-MER) program and the Murray-Darling Water and Environment Research Program (MD-WERP).

The research has been published in prestigious journals and won the R&D excellence award at the 2024 Australian Water Association's national awards.

Links to the papers are provided below.

• The floodplain inundation history of the Murray-Darling Basin through two-monthly maximum water depth maps.
• A Comprehensive Assessment of Floodwater Depth Estimation Models in Semiarid Regions.
• Development of a Multi-Index Method Based on Landsat Reflectance Data to Map Open Water in a Complex Environment.
• A synthesis of floodplain aquatic ecosystem metabolism and carbon flux using causal criteria analysis.
• Dynamic habitat modelling for water-dependent species in the Murray-Darling Basin.
• A method to predict connectivity for nomadic waterbird species from tracking data.