Ecospace Model Research Articles

Spatial optimization of protected area placement incorporating ecological, social and economical criteria

We describe two approaches for spatial optimization of protected area placement, both based on maximizing an objective function that incorporates ecological, social, and economical criteria. Of these, a seed cell selection procedure works by evaluating potential cells for protection one by one, picking the one that maximizes the objective function, adding seed cells. This continues to full protection of the project area. The other is a Monte Carlo approach, which uses a likelihood sampling procedure based on weighted importance layers of conservation interest to evaluate alternative protected area sizing and placement. This is similar to the objective function of Marxan, a priority-selection decision-support tool based on optimization algorithms using geographic information system data. The two approaches are alternative options in a common spatial optimization module, which uses the time- and spatial-dynamic Ecospace model for the evaluations. The optimizations are implemented as components of the Ecopath with Ecosim approach and software. In a case study, we find that there can be protected area zoning that will accommodate economical and social factors, without causing ecological deterioration. We also find a tradeoff between including cells of special conservation interest, and the economic and social interests. While this does not need to be a general feature, it emphasizes the need to use modeling techniques to evaluate the tradeoff.

Modeling the trophic effects of marine protected area zoning policies: A case study

Marine protected areas (MPAs) are increasingly being recognized as an alternative management tool for conserving marine resources and ecosystems. By integrating organism dispersal rates, ecosystem interactions and fishing effort dynamics, ECOSPACE, a spatially explicit ecosystem-based modeling tool, allowed us to compare the ecological consequences of alternative MPA zoning policies within the proposed Gwaii Haanas National Marine Conservation Area, located off the west coast of British Columbia, Canada. The desired effects of MPAs include higher fishery yields, the conservation of biodiversity, and/or the preservation of intact ecosystems. However, ECOSPACE predicts that when MPAs are small, species interactions and movements may make these objectives difficult to achieve. ECOSPACE suggests that the effects of MPAs are reduced at their boundaries where fishing effort is predicted to concentrate. Furthermore, top predators may become more abundant within MPAs, which could lead to a depression of their prey species and a subsequent increase of species at even lower trophic levels. Trophic cascade patterns and density gradients across boundaries are nontrivial departures from our simple expectations of how MPAs protect areas and will force us to reconsider what constitutes effective conservation. Our ECOSPACE model indicates that the establishment of multi-use buffer zones may help alleviate these realistic but worrisome ecological predictions. When coupled with an overall reduction in harvest pressure, ECOSPACE suggests that a MPA with a large core `no-take' zone and large buffer will result in the greatest increase in organism biomass. The use of marine zoning may be an effective management tactic to reduce social conflict and conserve marine ecosystems.

Dynamic energy budgets in biological systems

The deployment of offshore structures for renewable energy generation (wind/wave/tidal) will lead to the alteration of access to the area of installation for several users of the sea including: shipping, fishing, tourism and recreational users. Arguably, the largest impact will be upon the fishing industry where access loss may lead to displacement and reduced catch per unit effort in turn leading to conflict. To prevent conflict, it is important to understand mitigating factors. Marine renewable energy devices (MREDs) and associated infrastructure will be placed on the seabed, affecting benthic infauna and epifauna, important sources of food for many species including those of commercial importance, potentially providing benefits to the fishing industry and mitigating the causes of conflict. Two key plausible benefits of MREDs are the ‘artificial reef effect’ and the ‘exclusion zone effect’. This study investigated the utility of the Ecopath with Ecosim and Ecospace modelling software to address the implications of these ‘effects’. Two case study models were developed, one at the whole west coast of Scotland shelf scale and one at a smaller single installation scale. Our results suggested that the Ecospace model could potentially predict the effects of MRED installations, but revealed that there are a number of considerations which should be taken into account before attempting to do this. Key considerations include data availability (an issue in all modelling), spatial scale and resolution. Other limitations to this particular study such as the ability to make changes over time are currently being addressed by ongoing developments of the software. Despite the considerations and limitations, these case studies reveal the usefulness of spatial ecosystem modelling, particularly Ecospace, to investigate this issue.