Responses of fish assemblages to flooding of the Narran Lakes ecosystem, August 2008: Final Report to the New South Wales Department of Environment and Climate Change

Flow variability in floodplain semi-arid river systems has a fundamental influence on the aquatic environment that fish assemblages inhabit. To persist in these environments, fish must tolerate extreme hydrological variability at a range of spatial and temporal scales, and the associated availability of critical habitats (Balcombe et al. 2006). As such, their lifehistory must be able to accommodate rapid responses to varying flow events, in both their behaviour and through other means such as their spawning physiology. However, there is currently considerable debate amongst fish biologists as to the specific role of flow variability and its influence on the recruitment and maintenance of fish populations and assemblages in Australian floodplain rivers (Humphries et al. 1999; Mallen-Cooper and Stuart 2003; 2006). Clearly, a more rigorous understanding is required of the nature of any flow-related responses among these species, particularly given their lifehistory diversity (e.g. Growns 2004) and the structural and hydrological complexity of these river systems (Walker et al. 1995; Puckridge et al. 1998; Growns & Marsh, 2000). To achieve this, it will be necessary to use carefully designed event-based sampling programs to detect flow-related responses in their population and assemblage structure. In turn, this will ensure that conservation management practices are refined to maintain these unique environments and their fauna (Puckridge et al. 1998).