Table 2. List of environmental variables included in the models, with their category, unit of measurement, time period over which environmental data were calculated, justification for inclusion, references supporting inclusion and source of environmental data.
| Variable | Category | Units | Calculation period | Justification | Supporting references | Source |
|---|---|---|---|---|---|---|
| Annual mean accumulated soil water surplus | Flow | ML | 1970–2008 | Proxy for flow; considered a ‘master variable' likely to be correlated with habitat size, habitat complexity and physicochemical properties of rivers | (Poff et al., 1997; Stein et al., 2002; Bond et al., 2011) | NESAD |
| Coefficient of variation of annual totals of accumulated soil water surplus | Flow | NA | 1970–2008 | Proxy for variability in flows across years; should reflect long-term stability of water availability | (Bond et al., 2011) | NESAD |
| Mean accumulated soil water surplus for summer | Flow | ML | 1970–2008 | Proxy for summer flows; should reflect annual stability of water availability | (Bond et al., 2010; Bond et al., 2011) | NESAD |
| Flow regime disturbance index | Flow | Index scored between zero and one | 1989–1997 | Indicative of disruption to the natural flow regime; should reflect extent of flow regulation in rivers | (Bond et al., 2010; Koehn et al., 2014) | NESAD |
| Barrier free flow path length | Connectivity | % | 1990 | Measure of connectedness of streams; reflects number of dams and weirs that may pose barriers to fish movement | (Rathert et al., 1999; Lintermans et al., 2005) | NESAD |
| Baseline annual mean net primary productivity | Energy | tC ha−1 | 1788 | Proxy for long-term energy availability; should reflect long-term productivity of rivers | (Guégan et al., 1998) | NESAD |
| Stream and valley percentage extant forest cover | Habitat | % | 2001–2004 | Type and extent of vegetation surrounding stream; may influence the amount and type of overhanging vegetation and in-stream woody habitat | (Lintermans et al., 2005) | NESAD |
| Stream and valley percentage extant woodland cover | Habitat | % | 2001–2004 | Type and extent of vegetation surrounding stream; may influence the amount and type of overhanging vegetation and in-stream woody habitat | (Lintermans et al., 2005) | NESAD |
| Fish condition index | Habitat | Index scored between zero and one | 2008–2010 | Index that should predict healthy recruitment of native fish species | (MDBA, 2012) | SRA |
| Mean spring temperature | Temperature | °C | 1961–1990 | Proxy for water temperature | (Rowland, 1989; Lintermans et al., 2005; Koehn and Harrington, 2006) | BOM |
| Fish nativeness score | Invasive species | Index scored between zero and one | 2008–2010 | Score reflects abundance, biomass and species present that are native relative to alien | (Lintermans et al., 2005) | SRA |
Abbreviations: BOM, Bureau of Meteorology; ML, mega litre; NA, not applicable; NESAD, Sustainable Rivers Audit; SRA, Sustainable Rivers Audit; tC ha−1, tons of carbon per hectare.
Data were sourced from the NESAD v1.1.5 (available at: http://www.ga.gov.au/), SRA (MDBA, 2012) and the BOM (available at: http://www.bom.gov.au).