Browsing by Author "Pitcher, Grant C."

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    Declining oxygen in the global ocean and coastal waters
    (American Association for the Advancement of Science, 2018-01-05) Breitburg, Denise; Levin, Lisa A.; Oschlies, Andreas; Grégoire, Marilaure; Chavez, Francisco P.; Conley, Daniel J.; Garçon, Véronique; Gilbert, Denis; Gutiérrez, Dimitri; Isensee, Kirsten; Jacinto, Gil S.; Limburg, Karin E.; Montes Torres, Ivonne; Naqvi, S. W. A.; Pitcher, Grant C.; Rabalais, Nancy N.; Roman, Michael R.; Rose, Kenneth A.; Seibel, Brad A.; Telszewski, Maciej; Yasuhara, Moriaki; Zhang, Jing
    Oxygen is fundamental to life. Not only is it essential for the survival of individual animals, but it regulates global cycles of major nutrients and carbon. The oxygen content of the open ocean and coastal waters has been declining for at least the past half-century, largely because of human activities that have increased global temperatures and nutrients discharged to coastal waters. These changes have accelerated consumption of oxygen by microbial respiration, reduced solubility of oxygen in water, and reduced the rate of oxygen resupply from the atmosphere to the ocean interior, with a wide range of biological and ecological consequences. Further research is needed to understand and predict long-term, global- and regional-scale oxygen changes and their effects on marine and estuarine fisheries and ecosystems.
    Palabras clave:OxygenClimate changeOceanography
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    System controls of coastal and open ocean oxygen depletion
    (Elsevier, 2021-09-09) Pitcher, Grant C.; Aguirre-Velarde, Arturo; Breitburg, Denise; Cardich, Jorge; Carstensen, Jacob; Conley, Daniel J.; Dewitte, Boris; Engel, Anja; Espinoza-Morriberón, Dante; Flores, Georgina; Garçon, Véronique; Graco, Michelle; Grégoire, Marilaure; Gutiérrez, Dimitri; Hernandez-Ayon, José Martin; Huang, Huai-Hsuan May; Isensee, Kirsten; Jacinto, María Elena; Levin, Lisa; Lorenzo, Alberto; Machu, Eric; Merma, Lander; Montes Torres, Ivonne; Naqvi, S. W. A.; Paulmier, Aurelien; Roman, Michael; Rose, Kenneth; Hood, Raleigh; Rabalais, Nancy N.; Salvanves, Anne Gro V.; Salvatteci, Renato; Sánchez, Sonia; Sifeddine, Abdelfettah; Tall, Abdoul Wahab; van der Plas, Anja K.; Yasuhara, Moriaki; Zhang, Jing; Zhu, Z. Y.
    The epoch of the Anthropocene, a period during which human activity has been the dominant influence on climate and the environment, has witnessed a decline in oxygen concentrations and an expansion of oxygen-depleted environments in both coastal and open ocean systems since the middle of the 20th century. This paper provides a review of system-specific drivers of low oxygen in a range of case studies representing marine systems in the open ocean, on continental shelves, in enclosed seas and in the coastal environment. Identification of similar and contrasting responses within and across system types and corresponding oxygen regimes is shown to be informative both in understanding and isolating key controlling processes and provides a sound basis for predicting change under anticipated future conditions. Case studies were selected to achieve a balance in system diversity and global coverage. Each case study describes system attributes, including the present-day oxygen environment and known trends in oxygen concentrations over time. Central to each case study is the identification of the physical and biogeochemical processes that determine oxygen concentrations through the tradeoff between ventilation and respiration. Spatial distributions of oxygen and time series of oxygen data provide the opportunity to identify trends in oxygen availability and have allowed various drivers of low oxygen to be distinguished through correlative and causative relationships. Deoxygenation results from a complex interplay of hydrographic and biogeochemical processes and the superposition of these processes, some additive and others subtractive, makes attribution to any particular driver challenging. System-specific models are therefore required to achieve a quantitative understanding of these processes and of the feedbacks between processes at varying scales.
    Palabras clave:VentilationStratificationGlobal warming