Research Document 2024/024

Cumulative Impact Mapping and Vulnerability of Canadian Marine Ecosystems to Anthropogenic Activities and Stressors

By Murray, C.C., Kelly, N.E., Nelson, J.C., Murphy, G.E.P., and Agbayani, S.

Abstract

The consideration of cumulative effects, in efforts ranging from environmental assessment to marine spatial planning, continues to pose challenges for both scientists and managers. The assessment of cumulative effects is a rapidly evolving field with a diversity of approaches and methodologies. Cumulative impact mapping is one established method for representing the spatial impacts of multiple activities and stressors. Since its first publication by Ben Halpern and colleagues in 2008, cumulative impact mapping has been applied at various spatial scales in regions around the world, including Canada. It is an established, semi-quantitative model that spatially represents the additive effects of human activities and stressors on marine ecosystems. The cumulative impact mapping model involves compilation and standardization of high-quality spatially explicit marine data. Three sets of data are required:

1. Spatial representation of human activities and/or stressors,
2. Spatial representation of habitats (or species), and
3. A matrix of scores to represent the relative vulnerability of each habitat to each activity or stressor.

Impact scores are summed across all habitats and activities for each grid cell to produce a map of relative cumulative impact. The results of the model allow visualisation of the relative cumulative impact within the target region, highlighting areas most and least affected by human activities. In this paper, we give an overview of the cumulative impact mapping method and its application in Canadian waters. We present the results of an expert review of the vulnerability matrices for Pacific and Atlantic Canada and the suggested changes for use in cumulative impact mapping efforts going forward. Finally, we discuss the limitations and assumptions of the method and its applicability for various management contexts.

Research Document 2024/024 (PDF, 1,520 KB)

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