Reproductive ecology of Australia’s wet-dry tropical freshwater fish: insights into hydrological, environmental and biotic determinants of fish production

The rivers of northern Australia may well be the exception to the otherwise seemingly ubiquitous impacts of human development. To date, these rivers have seen only low levels of human development relative to comparatively sized rivers elsewhere in Australia, and climatologically similar regions throughout the world. However, this may change, with governments now increasingly supporting further development of northern Australia through industry, agriculture and mining activities, which all put pressure on the regions water resources and river flows.
Natural variability in a riverine flow regime is now widely recognised as being crucial for the reproductive success of fish species. However, the flow-reproductive ecology of Australian freshwater fishes has been patchily described, with a large and significant proportion of Australia’s freshwater fish fauna - the fish species of the far northern wet-dry tropics - receiving almost no attention. Even the most fundamental information - such as at what time of year and where do fish breed? - is lacking. Knowledge on the flow-reproductive ecology relationships of this fish fauna is essential for management of water resources in the region and for ongoing maintenance of biodiversity values.
This research aims to investigate the temporal, environmental and hydrological determinants of freshwater fish reproduction in the Australian wet-dry tropics. Using a model river catchment, this project aims to (i) identify what times of year and where freshwater fish reproduce; (ii) identify which combination of hydrological and environmental variables is most useful for predicting fish reproduction; (iii) examine how primary and secondary productivity interacts with larval fish abundance, and; (iv) identify if spatial and temporal variation in the sources of river discharge can affect the growth of fish larvae. Results from this study will provide a better understanding of the fundamentals of, and mechanisms behind, the reproductive ecology of Australian wet-dry tropical freshwater fish, the resources that young fish use and the spatial and temporal scales at which fish reproduction needs to be managed.