Recent Ecosystem Disturbance in the Northern California Current

An extended marine heat wave occurred across the North Pacific during 2014-2016, including the formation of the warm Blob followed by a strong El Nino in 2016. Coincident with this marine heat wave, we documented unprecedented biological changes in plankton and nekton in the Northern California Current (NCC) within pelagic surveys conducted over 20 years (1998-2017). The recent warm period was dominated by warmwater gelatinous invertebrates and fishes, some of which were previously either extremely rare or absent. Mixing of organisms originating from more southern or western regions with those previously present in the NCC may have resulted in novel and unpredictable trophic interactions that produced some of the observed changes in relative abundance. Continued long-term monitoring is needed to determine whether this is a temporary ecosystem disturbance or a fundamental change in the very productive NCC upwelling region.