Optimal thermal conditions for corals extend poleward with oceanic warming

The capacity for poleward range expansions beyond the tropics in corals hinges on ecophysiological constraints and resulting responses to climatic variability. We applied thermal physiological constraints of corals adapted to extreme seasonality in Hong Kong, specifically the minimum annual temperature and the proportion of time annually spent at seasonal extremes, to ask how warming will affect habitat suitability at the poleward range edges of these foundational species in the Northwest Pacific. Climate model projections reveal an easing of thermal constraints on the leading edge of coral ecophysiological limits with an expansion of thermally suitable habitat poleward by 2-7 degrees in latitude depending on the coral species and model considered. We also highlight a potential divergence of present and future thermal regimes that may lead to a mismatch in suitability for corals currently inhabiting high-latitude reefs. Understanding the thermal constraints on coral range expansions and defining the potential range of corals is critical for adaptive management that focuses on coral conservation and ensuring ecosystem function of existing subtropical and temperate ecosystems.