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The Use of Ecosystem Modelling for the Evaluation of Marine Protected Areas (MPAs) - the Great Barrier Reef - a Case Study
Queensland Department of Primary Industries Fisheries, CAIRNS, AUSTRALIA
Theme: TH5
The purpose of a Marine Protected Area (MPA) is to ensure the conservation and sustainability of the multi-species assemblage within that particular area; as representative of a habitat type or bioregion, for its own unique conservation values, or to ensure undisturbed recruitment or replenishment refugia for harvested species. Evaluation of potential MPAs, or assessing the effectiveness of those already in place, require tools that are sophisticated enough to describe the likely impact on a complex interrelated web of species that make up even the simplest of these assemblages. Ecosystem models, particularly those that are spatially explicit, have this capability. An ECOPATH model of the northern Great Barrier Reef was generalised and used as a tool to evaluate both theoretical MPAs and the series of Marine Representative Areas established by the Great Barrier Reef Marine Park Authority. Both the ECOSYM and ECOSPACE routines were used for temporal and spatial simulations of closing specific areas to commercial and recreational fishing to create conservation refugia. The additional scenario of closing areas to enhance commercial harvest in adjacent areas was also simulated. The results were in line with the Intermediate Disturbance Theory, where reduction in disturbance (fishing) reduced biodiversity as the ecosystem was allowed to stabilise at its 'climax' stage. Communities under low disturbance tend to be dominated by a few species of good competitors rather than by many species of colonisers.
