River conservation in a changing world: invertebrate diversity and spatial prioritisation in south-eastern coastal Australia E. Turak A,B,H , R. Marchant C , L. A. Barmuta D , J. Davis E , S. Choy F and L. Metzeling G A NSW Department of Environment, Climate Change and Water, PO Box A290, Sydney South, NSW 1232, Australia. B Australian Museum, Sydney, NSW 2000, Australia. C Museum Victoria, PO Box 666, Melbourne, Vic. 3001, Australia. D School of Zoology, University of Tasmania, Private Bag 5, Hobart, Tas. 7001, Australia. E School of Biological Sciences, Monash University, Clayton, Vic. 3800, Australia. F Queensland Department of Environment and Resource Management, GPO Box 2454, Brisbane, Qld 4001, Australia. G EPA Victoria, Ernest Jones Drive, Macleod, Vic. 3085, Australia. H Corresponding author. Email: eren.turak@environment.nsw.gov.au Abstract. Concentration of human populations with likely impacts of climate change present major challenges for river conservation in the south-eastern coastal region of Australia. Quantitative methods for spatial prioritisation of conservation actions can play a major role in meeting these challenges. We examined how these methods may be applied to help plan for potential impacts of climate change in the region, using macroinvertebrate assemblages as surrogates of river biodiversity. Environmental gradients explaining broad-scale patterns in the composition of macroinvertebrate assemblages are well represented in protected areas; however, their effectiveness for conserving river biodiversity with climate change depends on linking management inside and outside protected areas. Projected increases in temperature and sea level may be used to prioritise conservation to counter likely major impacts in high-altitude zones and the coastal fringes, whereas elsewhere, considerable uncertainty remains in the absence of better downscaled projections of rainfall. Applying such spatial prioritisations using biodiversity surrogates could help river-focussed conservation around the world. Additional keywords: climate change, freshwater conservation planning. Introduction Serious global decline in river biodiversity is occurring (Dud- geon et al. 2006). For example, 75% of fish species could face extinction by 2070 in rivers with reduced discharges (Xenopoulos et al. 2005). In Australia, the condition of inland aquatic systems, especially ephemeral and intermittent ones, is likely to decline, with many animal species at risk of extinction over the next 30–50 years under current rates of economic growth and patterns of land use and water management (Lake and Bond 2007). The biodiversity of rivers of the south-eastern coastal region of Australia may be at high risk because of con- centrated human settlement. In 2006, the South-East Coast Drainage Division (Fig. 1), occupying o 3.5% of Australia’s surface area, had just over 51% of the country’s population (Bureau of Rural Services 2010). This subjects the biodiversity of rivers and streams of the region to high levels of pollution, disruption of natural hydrological regimes, reduction in aquatic and riparian habitats, instream barriers and invasive species (Cullen 2003; Lake and Bond 2007). Such pressures will increase, given the growth projections in human populations. For example, Sydney’s population could increase by 63% and Melbourne’s population by 81% by 2056 (Australian Bureau of Statistics 2008). Climate change also threatens riverine biodiversity in the region. Rising temperatures, coupled with changes in hydrology and sea-level rise, will make instream environments unsuitable for many species. Temperature rises will be deleterious to high- altitude streams where cold stenotherms will probably lose their thermal refuges (Heino et al. 2009; Milner et al. 2009; Tierno de Figueroa et al. 2010). Projections for rainfall patterns in the region vary widely (Chiew and McMahon 2002), producing uncertain changes in river hydrology. A major reduction in total rainfall and increases in summer rainfall in the southern part of the region seem likely (Chiew and McMahon 2002), decreasing CSIRO PUBLISHING Marine and Freshwater Research, 2011, 62, 300–311 www.publish.csiro.au/journals/mfr Ó CSIRO 2011 10.1071/MF09297 1323-1650/11/030300