Home > T&I Project - Component 3. Food Webs


Component Summary

This research project is one of five components of the Institute’s Healthy Coorong, Healthy Basin Scientific Trials and Investigations Program.

The Food Webs Component will develop an integrated quantitative food web model that can assess how the food web will respond to various conditions (e.g. through management actions and interventions). This will be based on investigations of the food resources and conditions required to increase food resource availability and energy supply for key biota (waterbirds and fish) in the Coorong. The integrated food web model, coupled with hydrological and biogeochemical models, will provide a key management toolkit to assess how operational decisions would support the availability and quality of habitat, and the viability of fish and waterbird populations in the Coorong.

Component Detail

A functioning and resilient food web is critical to the ecological character of the Coorong, and is fundamental in the production and supply of energy to key biota, including waterbirds and fish. Freshwater inflows from the River Murray are considered highly beneficial to the food web structure of the Coorong, including providing a diversity of habitats (e.g. salinity gradient along the length of the Coorong); however, the ecological importance of the South-East flow is currently not known. Under suitable salinity, water level and nutrient conditions in the Coorong, the trophic productivity supports a diversity of biota across multiple trophic levels (Brookes et al. 2009, Deegan et al. 2010). Historically, the South Lagoon supported a diversity of waterbirds.

Recent conditions in the Coorong, including changes in the water level, salinity regime and potentially nutrient dynamics have altered the community composition of key food resources in the Coorong, including macroinvertebrates and aquatic plants, which are important ecological components and potential food sources for fish and waterbirds. There is limited understanding of the pathways by which nutrients pass from primary producers to waterbirds (Brookes et al. 2018), which limits our ability to predict the food web dynamics and ecological responses of some key biota, including fish and waterbirds, to changing conditions and management actions (e.g. including flow from the South-East and River Murray).

Figure 1. Semi-quantitative food-web structure for the Coorong at Pelican Point. Size of each box represents the biomass of the taxon (mg m-2dry weight (wt)). Boxes in dark represent the total biomass and light coloured boxes are the proportion epibenthic, planktonic or nektonic. Source: Geddes and Francis (2008).

Key Knowledge Gaps and Management Questions

This Component is addressing two key questions:

To answer these, the following research questions are being addressed:

Approach to addressing key knowledge gaps and management questions

Investigations are being conducted to:

This project has four key Activities to achieve these objectives:

Literature Cited

Brookes, J., Aldridge, K., Ganf, G., Paton, D., Shiel, R. & Wedderburn, S. (2009) Environmental watering for food webs in The Living Murray icon sites - a literature review and identification of research priorities. University of Adelaide, Adelaide.

Deegan, B.M., Lamontagne, S., Aldridge, K.T. & Brookes, J.D. (2010) Trophodynamics of the Coorong. Spatial variability in food web structure along a hypersaline coastal lagoon. CSIRO: Water for a Healthy Country National Research Flagship. CSIRO, Canberra.

 

 Figure 2. Conceptual food web of the Coorong using feeding functional guilds. Source: Giatas et al. (2018).