Regulation of the Respiration Quotient Across Ocean Basins. Issue 5 (29th September 2022)

• Record Type: Journal Article
• Authors: Moreno, Allison R.; Larkin, Alyse A.; Lee, Jenna A.; Gerace, Skylar D.; Tarran, Glen A.; Martiny, Adam C.
• Is Part Of: AGU advances. Volume 3:Issue 5(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-09-29
• Subjects: Redfield ratio -- respiration quotient -- oxygen -- nutrient stressors -- elemental stoichiometry; Earth sciences -- Periodicals; Space sciences -- Periodicals; 550
• DOI: 10.1029/2022AV000679
• Languages: English
• ISSNs: 2576-604X

Abstract

Abstract: A key uncertainty for predicting future ocean oxygen levels is the response and feedback of organic matter respiration demand. One poorly constrained component of the respiration demand is the oxygen‐to‐carbon remineralization ratio—the respiration quotient. Currently, multiple biological hypotheses can explain variation in the respiration quotient of organic matter produced in the surface ocean. To test these hypotheses, we directly quantified the particulate respiration quotient in 715 samples along a meridional section of the Atlantic Ocean and compared to previous Pacific Ocean observations. We demonstrate significant regional shifts in the respiration quotient and a two‐basin average of 1.16. Possible diel oscillations were also observed in the respiration quotient. Basin and regional variation in the respiration quotient were positively linked to temperature, N versus P stress, and plankton size structure. These observations suggest a complex regulation of the respiration quotient with important implications for the regional coupling of carbon and oxygen cycling. Plain Language Summary: Decreasing ocean oxygen levels due to climate change have serious consequences for marine life. Biological oxygen demand is impacted by the respiration quotient, but the mean and regional variation of this key ocean biogeochemical parameter a still poorly understood. Using direct chemical measurements of particulate organic matter in multiple ocean basins, we test proposed hypotheses for how the respiration quotient is regulated. We show evidence that the respiration quotient changes systematically with a hierarchy of temperature, nutrient stress, and phytoplankton community structure. These observations imply that a varying respiration quotient can an important driver of current and future ocean oxygen levels. Key Points: The respiration quotient ratios vary along latitudinal and meridional gradients A hierarchy of environmental conditions regulate the respiration quotient A varying oxygen‐to‐carbon remineralization ratio is important for connecting ocean biogeochemical cycles