Testing the generality of sea otter‐mediated trophic cascades in seagrass meadows

The presence and strength of trophic cascades can be a function the local abiotic environment relative abundance key species. reintroduction expansion sea otters Enhydra lutris , known keystone species in kelp ecosystems, southeast Alaska provides rare natural experiment to test generality apex‐predator – seagrass across broad spatial scale. We conducted an in‐depth community survey at 21 sites spanning ~100 km with variable otter for patterns alternating direct relationships between indicative cascades. Our analysis revealed some predicted by apex predator–seagrass theory, including strong negative relationship crabs many expected nitrate, seagrass, epiphytes epifauna. Other within cascade, however, were not supported no epifauna, critical link cascade. Given lack evidence all hypothesized relationships, we conclude that mediated cascade may present could due scale factors heterogeneity, low resource availability non‐linear food chains communities. However, correlation analyses suggest further interactions among biological environmental variables communities, positive biomass. These results effects recovering populations generalizable regions scales, highlighting need assessment on ecology management these populations.