Identifying Climate Refuges for Freshwater Biodiversity Across Australia: identification and characterisation of freshwater refuges in the face of climate change

Severe climatic changes are predicted for Australia before the close of this century. Climate change threatens biodiversity in all ecosystems; a management and conservation priority is to identify areas and habitats — refuges — that could shelter species from the worst impacts. Freshwater ecosystems contain high biodiversity, but are especially vulnerable to climatic changes due to their limited extent and connectivity. In much of Australia, they are highly susceptible to drying resulting from high variability in temperatures and rainfall. Identifying, protecting and managing refuges in freshwater systems must therefore be a key component of future conservation planning and policy. Using a variety of approaches, we explore the history and definitions of refuges in freshwater systems, assess the relatively stability and general refugial value of large-scale regions across the Australian continent and provide three case studies demonstrating applications of the continental analysis to inform more local adaptation strategies. A review of existing concepts of refuges for biodiversity highlights a number of issues that contribute to confusion and imprecision surrounding their definition, and we offer a new, simplified concept of refuges with respect to climate change in freshwater systems. Projected climate changes are highly spatially and seasonally variable, and this project has identified freshwater regions which will remain stable in the future, and those which will likely not. Many regions will likely experience climates and events well outside their current range of variability, and we predict significant changes in community structure and ecosystem assemblages. In these areas of instability, we propose that refuges will be of high priority, for example areas where temperature changes are buffered by vegetation or topographic shading. We show that some current protected areas will fail to offer refuge and protection under projected climatic changes. We further highlight significant changes in perenniality of streams and waterholes, particularily in the south-western region of Australia. Finally, our research identified a number of knowledge gaps which currently hinder climate change adaptation research in freshwater systems. We provide a discussion of these gaps and outline the future research directions required to ultimately benefit species and habitat conservation