Award: OCE-1458967

Climate and physiology shape biogeography, yet species? range limits can rarely be ascribed to fundamental organismal traits. We analyzed metabolic and temperature-dependent hypoxia traits across diverse species of marine animals to evaluate the hypothesis that aerobic energy demand imposes pervasive barriers to ocean habitat. Metabolic O2 demand and its temperature sensitivity are strongly compensated by the efficacy of O2 acquisition, reflecting selective pressure for hypoxia tolerance while reducing its inter-specific range. The remaining diversity of hypoxia traits yields habitat niches that span the world?s oceans, from shallow tropical to deep high latitudes, as observed in species distributions. Thermal and hypoxic limits of all species are substantially reduced by the energetic demands of ecological activity, a trait whose inter-specific frequency is identical for marine and terrestrial taxa. Active temperature-dependent hypoxia thus links the biogeography of diverse marine species to fundamental energetic requirements shared across the animal kingdom. Temperature-dependent hypoxia traits have strong and direct implications for the response of ecosystems to the warming of Earth?s climate. The rising temperature and declining oxygen of the subsurface ocean are projected to reduce the upper ocean?s metabolic index by ~20% globally and by ~50% in northern high-latitude regions, forcing poleward and vertical contraction of metabolically viable habitats and species ranges. Last Modified: 04/24/2019 Submitted by: Curtis Deutsch