California Current

Ranking and Mapping Human Threats to Marine Ecosystems in the California Current

Supported by the Gordon and Betty Moore Foundation

Cumulative Impacts Model

California Current:  Data


Quantitative assessment of spatial patterns of all human uses of the oceans and their cumulative effects is needed for implementing ecosystem-based management, marine protected areas, and ocean zoning.

Researchers applied methods developed to map cumulative impacts globally to the California Current using more comprehensive and higher-quality data for 25 human activities and 19 marine ecosystems.

They first surveyed experts in six sub-regions of the California Current to explore geographic variation in the effects of threats. A workshop was held to use decision theory to evaluate the tradeoffs of using expert opinion to assess threats and associated impacts. Data on ecosystems and threats were gathered at resolutions of approximately one square kilometer. By synthesizing information and inferences regarding anticipated impacts of threats, project participants developed a spatially-explicit understanding of the distribution and magnitude of human threats in the California Current. The analysis indicates where protection and threat mitigation are most needed in the California Current and reveals that coastal ecosystems near high human population density and the continental shelves off Oregon and Washington are the most heavily impacted. Climate change is the top threat, and impacts from multiple threats are ubiquitous. Remarkably, these results were highly spatially correlated with the global results for this region (R2=.92), suggesting that the global model provides guidance to areas without local data or resources to conduct similar regional-scale analyses.

Project collaborators are based at University of California, Santa Cruz; The Nature Conservancy; University of California, Santa Barbara; and the Monterey Bay National Marine Sanctuary.

Sponsor's Role: The Gordon and Betty Moore Foundation participates in general oversight of the project.

Ben Halpern
Carrie Kappel
Fio Micheli
Kim Selkoe

Mapping Cumulative Human Impacts to California Current Marine Ecosystems
Benjamin S. Halpern, Carrie V. Kappel, Kimberly A. Selkoe et al.
Conservation Letters  Online: April 17, 2009

Press Release at NSF

Interview on KCLU-FM