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Updated: Jun 16, 2026
10:28
Investigating the Relationship between Sea Surface Chlorophyll and Major Features of the South China Sea with Satellite Information
Published on: June 13, 2020
The Global Ocean Selenium Cycle Shaped by Phytoplankton Uptake and Community Structure
Peipei Wu1, Gregory A Cutter2, Amina T Schartup1
1Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92037, United States.
Environmental Science & Technology
|June 13, 2026
Summary
Marine phytoplankton, especially cyanobacteria, significantly impact ocean selenium (Se) cycling and distribution. This study reveals previously unknown Se utilization by these microbes, affecting nutrient availability and food webs.
Area of Science:
- Marine chemistry and biogeochemical cycles.
- Oceanography and microbial ecology.
- Essential micronutrient dynamics in marine ecosystems.
Background:
- Selenium (Se) is vital for human health, with oceans as a key source, but its marine biogeochemical cycling is poorly understood.
- Phytoplankton are known to influence nutrient profiles, but their role in selenium speciation and distribution requires further investigation.
- Cyanobacteria, dominant in oligotrophic regions, were previously not considered significant selenium users.
Purpose of the Study:
- To develop the first global 3-D ocean model for selenium speciation and distribution.
- To identify key processes controlling marine selenium cycling.
- To investigate the role of phytoplankton, particularly cyanobacteria, in selenium uptake and depletion.
Main Methods:
- Development of a global 3-D ocean model for selenium.
- Constraining the model with field observations and laboratory experiments.
- Analyzing selenium speciation (selenite Se(IV) and selenate Se(VI)) and distribution patterns.
Main Results:
- Biological uptake by phytoplankton is the primary driver of horizontal and vertical inorganic selenium gradients.
- Oligotrophic regions with cyanobacteria show significant inorganic selenium depletion, indicating unrecognized Se utilization.
- The model shows a short residence time for selenite (Se(IV)) in the euphotic zone, suggesting potential limitation and a shift towards selenate (Se(VI)) uptake.
- A rapid cycling mechanism involving Se(VI) assimilation, organic Se production, and Se(IV) regeneration facilitates selenium availability.
Conclusions:
- Phytoplankton community composition critically controls ocean selenium cycling and speciation.
- Unrecognized selenium utilization by cyanobacteria impacts nutrient dynamics in vast ocean regions.
- Oceanographic changes affecting phytoplankton communities will alter selenium availability, microbial resilience, and marine food webs.
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