Articles | Volume 22, issue 19
https://doi.org/10.5194/bg-22-5257-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-22-5257-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
02 Oct 2025
Research article |
| 02 Oct 2025
| 02 Oct 2025
Photosynthetic electron, carbon, and oxygen fluxes within a mosaic of Fe limitation in the California Current upwelling system
Department of Earth, Oceans and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada
Kate Schuler
Department of Earth, Oceans and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada
Emily Speciale
Earth Marine and Environmental Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
Adrian Marchetti
Earth Marine and Environmental Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
Claire Till
Department of Chemistry, California State Polytechnic University, Humboldt, Arcata, CA, USA
Ralph Till
Department of Chemistry, California State Polytechnic University, Humboldt, Arcata, CA, USA
Philippe Tortell
Department of Earth, Oceans and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada
Department of Botany, University of British Columbia, Vancouver, BC, Canada
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We investigated how hyperspectral optical data collected in the North Pacific can be used to determine the phytoplankton community composition. We used the optically derived infomation of the phytoplankton community to examine the phytoplankton sizes, oceanographic controls and links to other biogeochemical variables. This work was motivated by the upcoming launch of the PACE satellite by NASA and the increased availability of hyperspectral optical measurements in oceanographic studies.
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Marine heat waves (MHWs) are a frequent event in the northeast Pacific, with a large impact on the region's ecosystems. Large phytoplankton in the North Pacific Transition Zone are greatly affected by decreased nutrients, with less of an impact in the Alaskan Gyre. For small phytoplankton, MHWs increase the spring small phytoplankton population in both regions thanks to reduced light limitation. In both zones, this results in a significant decrease in the ratio of large to small phytoplankton.
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The trace gas dimethyl sulfide (DMS) plays an important role in the ocean sulfur cycle and can also influence Earth’s climate. Our study used two statistical methods to predict surface ocean concentrations and rates of sea–air exchange of DMS in the northeast subarctic Pacific. Our results show improved predictive power over previous approaches and suggest that nutrient availability, light-dependent processes, and physical mixing may be important controls on DMS in this region.
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The oceans are a net source of the major greenhouse gases; however there has been little coordination of oceanic methane and nitrous oxide measurements. The scientific community has recently embarked on a series of capacity-building exercises to improve the interoperability of dissolved methane and nitrous oxide measurements. This paper derives from a workshop which discussed the challenges and opportunities for oceanic methane and nitrous oxide research in the near future.
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Short summary
We recorded three metrics of photosynthesis in the California Current. Real-time observations of microalgae physiology and productivity revealed signs of iron limitation where the continental shelf rapidly dropped off. Iron limitation influenced how efficiently light was absorbed and used for carbon fixation but did not appear to affect net photosynthetic oxygen production. Our results offer useful insights into efforts to model carbon fixation rates from microalgae optical properties.
We recorded three metrics of photosynthesis in the California Current. Real-time observations of...
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