Connecting the dots in the Gulf of the Farallones : linking physical ocean conditions to the ecological success of planktivorous predators

Pelagic ecosystem links are typically studied separately with predator response often invoked from climate change, while intermediary alteration in nutrients and plankton production are inferred as the root cause. More specifically, we explored how Pacific climate forces regional upwelling, drives oceanography, nutrients, plankton production and translated into observed predator abundances in the Gulf of the Farallones. We determined key pathways of those drivers with using a spatiotemporal approach to path analysis for a suite of mid and upper trophic level consumers. We found offshore ocean conditions predicted abundance of boreal/cold water copepods and these conditions also support krill abundance. We modeled three krill-predators in the offshore region: blue whales, Chinook salmon, and Cassin’s auklet. We found blue whales and salmon associated with krill biomass, however Cassin’s auklets associated with environmental conditions that influenced krill availability. Although these predators depend on the same prey, they responded differently to environmental drivers and biological resources, highlighting the need to study individual species responses to environmental change. Understanding how these drivers influence responses of upper trophic level species is important in supporting adaptive ecosystem management in the face of rapidly changing climate.