Persistence of trophic hotspots and relation to human impacts within an upwelling marine ecosystem

Human impacts (e.g., fishing, pollution, and shipping) on pelagic ecosystemsare increasing, causing concerns about stresses on marine food webs. Maintaining predator–prey relationships through protection of pelagic hotspots is crucial for conservation and management of living marine resources. Biotic componentsof pelagic, plankton-based, ecosystemsexhibit high variability in abundance in time and space (i.e., extreme patchiness), requiring investigation of persistence of abundance across trophic levelsto resolve trophic hotspots. Using a 26-yr record of indicators for primary production, secondary (zooplankton and larval fish), and tertiary ( seabirds) consumers, we show distributions of trophic hotspots in the southern California Current Ecosystemresult from interactions between a strong upwelling center and a productive retention zone with enhanced nutrients, which concentrate prey and predators across multiple trophic levels. Trophic hotspots also overlap with human impacts, including fisheries extraction of coastal pelagic and groundfishspecies, as well as intense commercial shipping traffic. Spatial overlap of trophic hotspots with fisheries and shipping increases vulnerability of the ecosystemto localized depletion of forage fish, ship strikes on marine mammals, and pollution. This study represents a critical step toward resolving pelagic areas of high conservation interest for planktonic ecosystemsand may serve as a model for other ocean regions where ecosystem-based managementand marine spatial planningof pelagic ecosystemsis warranted.