Climate change threatens freshwater ecosystems, both directly and by intensifying stressors such as expansion of invasive species. Historical extreme climate events like Australia's last glacial maximum show the lasting effects when ecosystems surpass crucial thresholds.
In dryland rivers, waterholes act as drought refuges, essential for native fish survival. Loss of waterholes represents a critical ecological threshold. Fish require networks of waterholes to endure droughts with more individuals surviving where there are more waterholes. Yet, water resource developments that extend no-flow periods and sedimentation that reduces waterhole depth threaten these vital refuges. But what is the impact of climate change?
We assessed representative waterholes using relevant global circulation models to forecast their future persistence by 2050, considering different possible carbon emission pathways.
Under climate change scenarios evaporation rates were higher and droughts longer, with severity varying across global circulation models and carbon emission pathways. However, trends were consistent for climate change to cause more extensive and more frequent waterhole failures, placing even permanent refuges at risk.
If these predictions are realised climate change will lead to significant population and species losses of native fishes in dryland rivers, emphasising the likely need for active management of these ecosystems amid evolving climate conditions.