LAUSR

Significance As climate change increasingly stresses Earth’s biosphere, assessment of biotic responses is critical to human welfare. Although species-level changes have been researched for decades, studies focused at the multispecies level are infrequent, and those testing dynamical responses (species interactions, recovery from disturbance) even rarer. In the well-studied, iconic rocky intertidal ecosystem, annually repeated disturbance experiments in 2012–2019 revealed that the resilience of communities weakened (recovery rates slowed) and variability in recovery rates increased. These changes were associated with increased thermal stresses and shifts in upwelling currents, which can alter growth, decrease colonization rates, and kill organisms. Climate change threatens to destabilize ecological communities, potentially moving them from persistently occupied “basins of attraction” to different states. Increasing variation in key ecological processes can signal impending state shifts in ecosystems. In a rocky intertidal meta-ecosystem consisting of three distinct regions spread across 260 km of the Oregon coast, we show that annually cleared sites are characterized by communities that exhibit signs of increasing destabilization (loss of resilience) over the past decade despite persistent community states. In all cases, recovery rates slowed and became more variable over time. The conditions underlying these shifts appear to be external to the system, with thermal disruptions (e.g., marine heat waves, El Niño–Southern Oscillation) and shifts in ocean currents (e.g., upwelling) being the likely proximate drivers. Although this iconic ecosystem has long appeared resistant to stress, the evidence suggests that subtle destabilization has occurred over at least the last decade.