title: Climate-forced variability of ocean hypoxia.
abstract: Oxygen (O(2)) is a critical constraint on marine ecosystems. As oceanic O(2) falls to hypoxic concentrations, habitability for aerobic organisms decreases rapidly. We show that the spatial extent of hypoxia is highly sensitive to small changes in the ocean's O(2) content, with maximum responses at suboxic concentrations where anaerobic metabolisms predominate. In model-based reconstructions of historical oxygen changes, the world's largest suboxic zone, in the Pacific Ocean, varies in size by a factor of 2. This is attributable to climate-driven changes in the depth of the tropical and subtropical thermocline that have multiplicative effects on respiration rates in low-O(2) water. The same mechanism yields even larger fluctuations in the rate of nitrogen removal by denitrification, creating a link between decadal climate oscillations and the nutrient limitation of marine photosynthesis.
authors.affiliation: Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA 90095, USA. cdeutsch@atmos.ucla.edu
authors.forename: Curtis
authors.initials: C
authors.lastname: Deutsch
authors.forename: Holger
authors.initials: H
authors.lastname: Brix
authors.forename: Taka
authors.initials: T
authors.lastname: Ito
authors.forename: Hartmut
authors.initials: H
authors.lastname: Frenzel
authors.forename: LuAnne
authors.initials: L
authors.lastname: Thompson
mesh_terms: D000693:Anaerobiosis; D057231:Climate Change; D003198:Computer Simulation; D058440:Denitrification; D017753:Ecosystem; D009584:Nitrogen / Q000378:metabolism; D009792:Oceans and Seas; D010100:Oxygen / Q000032:analysis* / Q000378:metabolism; D010140:Pacific Ocean; D012623:Seawater / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors; D014872:Water Movements
chemical_list: D009584:Nitrogen; D010100:Oxygen