Climate change and its implications for Australia's freshwater fish

Abstract

Abstract. Freshwater environments and their fishes are particularly vulnerable to climate change because the persistence and quality of aquatic habitat depend heavily on climatic and hydrologic regimes. In Australia, projections indicate that the rate and magnitude of climate change will vary across the continent. We review the likely effects of these changes on Australian freshwater fishes across geographic regions encompassing a diversity of habitats and climatic variability. Commonalities in the predicted implications of climate change on fish included habitat loss and fragmentation, surpassing of physiological tolerances and spread of alien species. Existing anthropogenic stressors in more developed regions are likely to compound these impacts because of the already reduced resilience of fish assemblages. Many Australian freshwater fish species are adapted to variable or unpredictable flow conditions and, in some cases, this evolutionary history may confer resistance or resilience to the impacts of climate change. However, the rate and magnitude of projected change will outpace the adaptive capacities of many species. Climate change therefore seriously threatens the persistence of many of Australia's freshwater fish species, especially of those with limited ranges or specific habitat requirements, or of those that are already occurring close to physiological tolerance limits. Human responses to climate change should be proactive and focus on maintaining population resilience through the protection of habitat, mitigation of current anthropogenic stressors, adequate planning and provisioning of environmental flows and the consideration of more interventionist options such as managed translocations.

High-resolution projections of surface water availability for Tasmania, Australia

“…The projected decreases in DJF runoff over western Tasmania are caused by a reduction in the mean westerly circulation , associated with an expansion of the Hadley cell and a poleward movement of the mid-latitude storm tracks (Yin, 2005), including a poleward movement and strengthening of the subtropical ridge of high pressure and an increase in the high phase of the southern annular mode (Kushner et al, 2001). Even though reduced DJF streamflows in the west have little impact on annual streamflow volumes, these changes are likely to have deleterious effects on endemic freshwater fish (Morrongiello et al, 2011).…”

A review of on-ground recovery actions for threatened freshwater fish in Australia

“…knee-jerk reactions to increase stockenhancement activities for recreationally desirable species) (Lintermans and Cottingham 2007). Extreme events are likely to increase in frequency in Australia with climate change (Alexander and Arblasterc 2009;Morrongiello et al 2011), and incorporating into recovery planning the lessons from the past decade should be a priority.…”

Projected climate change in Australian marine and freshwater environments

“…Seasonal differences are also apparent, with winter rainfall declining over most of the country, whereas summer rainfall may increase in some parts of northern Australia (Suppiah et al 2007;see www.climatechangeinaustralia.gov.au, 24 August 2011). Salinity problems, which can occur throughout lower parts of a river system and are problematic in south-western Australia and the Murray-Darling regions, may be exacerbated by changes in rainfall, temperature and stream flows (Morrongiello et al 2011;Pratchett et al 2011). Lower flows and higher temperatures may also reduce water quality within the catchment.…”

“…Some inland 'freshwater' habitats in Australia are already considered hypersaline (e.g. Lake Eyre basin) and the fauna that inhabit them possess characteristics that promote tolerance of such extreme environments (see discussion in Morrongiello et al 2011). However, critical thresholds for most species are unknown.…”