Applying portfolio effects to the Gulf of Alaska ecosystem: Did multi-scale diversity buffer against the Exxon Valdez oil spill?

Understanding how ecosystems respond to environmental variability and large perturbations is a central problem in ecology. The Exxon Valdez oil spill was an extremely large perturbation to the Gulf of Alaska (GOA) ecosystem. However, because species and populations differ in the timing and magnitude of response to perturbations, the effects of the oil spill may be difficult to detect. We propose an NCEAS working group centered on the application of portfolio theory in the GOA using novel spatiotemporal modeling approaches. We will synthesize time-series from the GOA ecosystem and fisheries. Our goals are to: 1. Synthesize the temporal and spatial scales of biomass, growth, and recruitment variability for herring, salmon, groundfish, and crabs, and compile existing studies on climate forcing on these taxa in the GOA 2. Examine the role of diversity in stabilizing a) temporal dynamics of plankton and focal fish species, and b) catch portfolios in the GOA pre- and post-oil spill 3. Investigate evidence for changing species interactions and community resilience using multispecies models applied to plankton, fish, and Steller sea lions in Prince William Sound and the GOA We will use recently developed multivariate spatiotemporal models to build on previous syntheses of GOA data and investigate the role of climate drivers and ecological interactions. We will evaluate the effects of the oil spill after accounting for these other drivers. Our synthesis will improve understanding of the role of multiple sources of variability in structuring GOA communities and advance new methods in spatiotemporal modeling. The methodology we develop will be broadly applicable to exploited marine ecosystems around the world.