Article

Environmental Management

, Volume 50, Issue 1, pp 1-10

Putting the “Ecology” into Environmental Flows: Ecological Dynamics and Demographic Modelling

  • Will ShentonAffiliated withAustralian Centre for Biodiversity, School of Biological Sciences, Monash University
  • , Nicholas R. BondAffiliated withAustralian Centre for Biodiversity, School of Biological Sciences, Monash UniversityAustralian Rivers Institute, Griffith University
  • , Jian D. L. YenAffiliated withAustralian Centre for Biodiversity, School of Biological Sciences, Monash University
  • , Ralph Mac NallyAffiliated withAustralian Centre for Biodiversity, School of Biological Sciences, Monash University Email author 

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Abstract

There have been significant diversions of water from rivers and streams around the world; natural flow regimes have been perturbed by dams, barriers and excessive extractions. Many aspects of the ecological ‘health’ of riverine systems have declined due to changes in water flows, which has stimulated the development of thinking about the maintenance and restoration of these systems, which we refer to as environmental flow methodologies (EFMs). Most existing EFMs cannot deliver information on the population viability of species because they: (1) use habitat suitability as a proxy for population status; (2) use historical time series (usually of short duration) to forecast future conditions and flow sequences; (3) cannot, or do not, handle extreme flow events associated with climate variability; and (4) assume process stationarity for flow sequences, which means the past sequences are treated as good indicators of the future. These assumptions undermine the capacity of EFMs to properly represent risks associated with different flow management options; assumption (4) is untenable given most climate-change predictions. We discuss these concerns and advocate the use of demographic modelling as a more appropriate tool for linking population dynamics to flow regime change. A ‘meta-species’ approach to demographic modelling is discussed as a useful step from habitat based models towards modelling strategies grounded in ecological theory when limited data are available on flow-demographic relationships. Data requirements of demographic models will undoubtedly expose gaps in existing knowledge, but, in so doing, will strengthen future efforts to link changes in river flows with their ecological consequences.

Keywords

Demographic models Environmental flows Demographic modelling Habitat-suitability models Meta-species