WAMSI Node 4.3.2 - Ecosystem Modelling - Overall

Researchers: Beckley, Lynnath (Author) ,  Brooker, Michelle (Author) ,  Dambacher, Jeffrey, Dr (Author) ,  Davis, John (Author) ,  Fretzer, Sarah (Author)
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Brief description Two modelling approaches are being used in this study, i.e. a quantitative modelling and a qualitative modelling approach. They are being developed for the estuarine ecosystems of the Swan River, Peel-Harvey and Leschenault estuaries will be used to explore how environmental changes arising from both anthropogenic and non-anthropogenic factors are likely to affect those ecosystems. The models will also be used to assess the potential to ameliorate adverse impacts through management actions

Lineage Statement: Two modelling approaches are being used in this study, i.e. a quantitative modelling and a qualitative modelling approach. In the first of these approaches, the estuarine ecosystem is represented by an Ecopath model, i.e. a mass-balance model, which describes the trophic interactions among the different functional groups into which the biota of the estuarine ecosystem have been classified. The dynamics of the resulting model may be explored using Ecosim, while Ecospace may be used to explore aspects of the system's behaviour that relate to the spatial distribution of the functional groups within the Estuary, which are determined by the distribution of different habitat types within the system. The estimates of biomass, production, and consumption and the composition of the diets of the various functional groups have been determined by undertaking an extensive review of the scientific literature and reports of studies relating to the estuary and its catchment, and by conducting workshops with stakeholders, managers, community representatives and scientists. The information obtained from this data gathering exercise is collated and synthesised to produce the data that are input to Ecopath. Where data from the Peel-Harvey Estuary are not available, data from the same or similar functional groups in other ecosystems are used to provide the values that are input to the model. After balancing and tuning, and extension to describe the distribution of the functional groups with respect to habitat, the resulting Ecosim and Ecospace models provide tools to explore the consequences of changes to the ecosystem. For the second method, the estuarine ecosystem is represented in a qualitative model using a set of variables that depict the more important biological, social and economic components of the aspect of the system that is being explored. The interactions between these variables are represented as a set of bidirectional links. The variables and interactions are identified by undertaking an extensive review of the scientific literature and reports of studies relating to the estuary and its catchment, and by conducting workshops with stakeholders, managers, community representatives and scientists. The information is used to define one (or more) digraphs representing the major interactions and variables. Through use of loop analysis, the stability of the system can be assessed, feedback loops identified, and the way in which other variables are affected when a press perturbation is applied to a selected variable may be assessed. The resulting model is a valuable tool for exploring the response of the ecosystem to management intervention.

Lineage Statement: No new data are collected. The modelling process collates, integrates and synthesises existing data. The ecosystems models are developed using published data and information gained through workshop discussions and interviews with key managers, stakeholders and scientists, the results of which are represented in the ecosystem models that are developed and described in the reports that are produced to describe the modelling results.

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