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Sternberg D.,Griffith University | Kennard M.J.,Griffith University | Kennard M.J.,National Environmental Research Program Northern Australia Hub | Balcombe S.R.,Griffith University
Global Ecology and Biogeography | Year: 2014

Aim This study aims (1) to quantify the broad-scale patterns of functional diversity and life-history strategies of freshwater fish in relation to environmental variation across Australian river basins and (2) to identify key life-history traits associated with species extinction risk in order to determine how fish communities and extinction-prone species may respond to future environmental change. Location One hundred and twenty-three river basins across eastern Australia. Methods Based on 10 key life-history traits for 194 freshwater fish we used a novel analytical approach to quantify multivariate life-history indices in relation to environmental variation within a spatio-phylogenetic framework. We assessed the utility of our analytical framework by contrasting final models against all candidate models, both with and without an eigenvector filtering procedure, and quantified the degree of autocorrelation in all model residuals. Results Temperature, habitat heterogeneity/availability, flow variability and primary productivity accounted for between 55 and 80% of the variation in lifehistory indices. Best-performing models were all derived from the addition ofspatial and phylogenetic covariates to the analytical framework which consistently produced more parsimonious final models with higher explanatory power and insignificant levels of autocorrelation in the model residuals. Main conclusion The life-history functional diversity of fish assemblages and the composition of life-history strategies across Australian river basins is in part determined by environmental variability, stability and seasonality, highlighting both the importance of environmentally driven community assembly processes and thepotential changes to freshwater fish biodiversity in response to climate change. A spatio-phylogenetic analytical framework is a key component in the effective management of autocorrelation in ecological data and the derivation of more rigorous trait-environment relationships. © 2014 John Wiley & Sons Ltd. Source


King A.J.,National Environmental Research Program Northern Australia Hub | King A.J.,Charles Darwin University | Townsend S.A.,National Environmental Research Program Northern Australia Hub | Douglas M.M.,National Environmental Research Program Northern Australia Hub | And 3 more authors.
Freshwater Science | Year: 2015

Balancing the freshwater needs of humans and ecosystems is a fundamental challenge for the management of rivers worldwide. River regulation and water extraction can affect all components of the natural flow regime, yet few studies have investigated the effects on the low-flow end of the hydrograph. Low-flow periods are hydrologically distinctive and ecologically important, varying in nature among climatic zones. Tropical savannah rivers are characterized by highly seasonal and predictable flow regimes, but with high interannual variation in the magnitude, timing, and duration of low flows. Many tropical savannah rivers are relatively intact, especially in northern Australia, but many are now receiving increasing attention for water-resource development through surface- and groundwater extraction. We identified the hydroecological effects of water extraction on 3 phases of the seasonal flow regime: the wet-dry transition, dry season, and dry-wet season transition for perennial and intermittent rivers in tropical savannah climates. We propose a conceptual model and 7 predictions that describe the ecological implications of dry-season water extraction in tropical savannah river systems worldwide. The predictions address: 1) connectivity, 2) availability of in-stream habitat, 3) dry-season persistence of in-channel refugia, 4) water quality during dry-wet and wet-dry transition periods, 5) decoupling of wet- and dry-season flows, and the cumulative effects on 6) groundwater-dependent species and 7) whole-ecosystem shifts. We used northern Australia as a case study to review the current level of evidence in support of these predictions and their potential ecological consequences, and used this review to propose key priorities for future research that are globally applicable. © 2015 by The Society for Freshwater Science. Source

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