Behavioral responses across a mosaic of ecosystem states restructure a sea otter-urchin trophic cascade

Consumer and predator foraging behavior can impart profound trait-mediated constraints on community regulation that scale-up to influence the structure and stability of ecosystems. Here we demonstrate how the behavioral response of an apex predator to changes in prey behavior and condition can dramatically alter the role and relative contribution of top-down forcing, depending on the spatial organization of ecosystem states. In this study, a rapid and dramatic decline in the abundance of a meso-predator (Pycnopodia helianthoides) and primary producer (Macrocystis pyrifera, ‘kelp’) coincided with a fundamental change in purple sea urchin (Strongylocentrotus purpuratus) foraging behavior and condition, resulting in a spatial mosaic of kelp forests interspersed with patches of sea urchin barrens. We show that this mosaic of adjacent alternative ecosystem states led to an increase in the number of sea otters (Enhydra lutris nereis) specializing on urchin prey, a population-level increase in...