Objectives
The hydrological variability of intermittent streams means that the spatial distribution of aquatic refuges within river networks and the temporal dynamics of hydrological connectivity between them are critical for the persistence of aquatic biodiversity. We demonstrate a new approach to identify surface waterbodies as potential refuges for freshwater biodiversity in river networks and efficiently prioritise them for on-ground conservation management.
Design and Methodology
We developed models of surface water extent and of daily streamflow to represent spatio-temporal variation in surface water extent and hydrological connectivity within river networks of eastern Australia over a 107-year period. We also assembled spatially-explicit freshwater fish species distribution data as targets for refugia prioritisation and elicited estimates of their relative mobility potential within river networks. We then applied a systematic prioritisation algorithm to identify areas that provide all resident fish species with access to a minimum number of aquatic refuges while maximizing the length of stream potentially accessible for recolonisation after dry periods.
Original data and results
Simulated long-term variations in streamflow intermittency and surface water extent were highly dynamic through space and time over the past century. A subset of highly irreplaceable aquatic refuges for freshwater fish were identified that were widely-distributed throughout the river networks, encompassing main stems to headwater streams. A set of on-ground conservation management actions to maintain the refugial-values of these areas is recommended to minimize disturbance from livestock and feral animals, pollution, water extraction, local aquifer drawdown, and other threats.
Conclusion
Our study presents a novel and practical approach to identify priority aquatic refuges for targeted conservation management to enhance the resistance and resilience of freshwater biodiversity in intermittent stream ecosystems.