A hierarchical risk assessment framework for ecosystem based management

There is general agreement that assessment of risk in the marine environment needs to move toward an ecosystem approach to account for the single and cumulative impacts from multiple sectors that operate within the world’s oceans.

Despite there being fewer marine activities than in terrestrial environments, marine systems are challenging to manage on an ecosystem basis as a result of their complexity, high degree of connectivity and difficulties associated with observing ocean processes, flora and fauna. These challenges can make it difficult for researchers to know how to make best-use of available scientific information to inform policy makers about options for ecosystem management. A broad range of scientific tools and approaches have emerged to attempt to meet these differing needs and together these challenges and choices have stymied decision makers.
There is a clear need to develop a process that can assist governments and other decision makers to reduce the uncertainty around the risks of significant impacts in ecosystem based management. An important consideration in developing a framework for risk-based approach to ecosystem management is clarifying the terminology associated with the assessment, this is particularly important for facilitating collaboration between researchers and policy makers.

We suggest that a productive way to approach this would be to use a hierarchical approach where a range of tools can be used to identify activities that have a high risk of significant impact. We use values (eg conservation, resource or community) that have been described through an expert process to identify the relevant subsystem for management. The first level builds a conceptual model of the relevant subsystem and identifies the pressures that act on that subsystem. The second level uses mathematical qualitative models to refine the understanding of the system and to reduce the uncertainty around the system structure. The final level uses quantitative and qualitative models to identify specific thresholds, management trigger points and scenarios. Each level reduces the uncertainty in decisions but increase the costs and time taken.

The hierarchical framework proposed in this paper provides scientists and policy makers with guidance and a common lexicon for assessing cumulative risks and estimating impacts to marine ecosystems. The framework provides for a cost-effective and consistent approach to assessments, accommodating a broad range of marine environment assessment cases, leading to priorities for action. The approach acknowledges the importance of ecosystem models for estimating cumulative risks and provides a frame for understanding how they can be cost-effectively and consistently applied to estimate impacts and improve understanding.


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