Download the completed thesis as a pdf here.
And a related climate change media release here.
Background
Different fish eat different things. What they eat depends on what species they are, where they are, how big they are and what (and how much) food is available.
By examining the diets a number of fish of each size and species under different flow conditions, we can find identify what food sources are most important and how the fish respond to changes in food availability. We can also ask, does the distribution of fish change with fluctuations in prey abundance, or are other facts, such as habitat structure also important?
This provides us with an insight into how river systems work as a whole and how we can better manage them in a changing climate.
Study location and methods
My PhD was conducted on the beautiful, but somewhat degraded Mulgrave River, near Cairns in Australia’s Wet Tropics.
A combination of electrofishing and gill nets are being used to capture fish. Water quality, habitat and invertebrate abundance data were also being collected.
Stable isotopes analysis was used to provide additional information on energy transfer through the aquatic food web.
Results
The final thesis presents a model of seasonal fish community dynamics that can act as a framework for future research and management - it's essentially a guide to how the lowland section of the river works.
The results of this study emphasise the importance of flow seasonality in governing the spatial and temporal dynamics of productivity, instream habitat, invertebrate and fish populations, fish feeding and, therefore, the structure and function of aquatic food webs.
I hope community groups, such as members of Mulgrave River Landcare, find the information useful in their future decisions regarding river use and restoration of the river.
Support
The study was supported by the Rainforest CRC under the Catchment to Reef program. This organisation has been superseded by MTSRF.
