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ORIGINAL RESEARCH article

Front. Mar. Sci.
Sec. Marine Biogeochemistry
Volume 12 - 2025 | doi: 10.3389/fmars.2025.1529163

Hypoxia lowers cell carbon and nitrogen content and accelerates sinking of a marine diatom Thalassiosira pseudonana

Provisionally accepted
Bokun Chen Bokun Chen 1Hui Song Hui Song 1*Ge Xu Ge Xu 2Hongli Ji Hongli Ji 1Xue Yang Xue Yang 1Gang Li Gang Li 3*
  • 1 Shandong University, Jinan, China
  • 2 Marine Environmental Monitoring Centre of Ningbo, East China Sea Bureau of Ministry of Natural Resources, Ningbo, China
  • 3 Daya Bay Marine Biology Research Station, Chinese Academy of Sciences, Shenzhen, China

The final, formatted version of the article will be published soon.

    The positive or negative effect of a decrease in dissolved O 2 on the photophysiology of phytoplankton is determined by the duration of light exposure. To uncover the underlying mechanisms, the marine model diatom Thalassiosira pseudonana was cultured under three dissolved O 2 levels (8.0 mg L -1 , Ambient O 2 ; 4.0 mg L -1 , Low O 2 ; and 1.3 mg L -1 , Hypoxia) to compare its growth, cell composition and physiology between the light and dark periods. The results showed that the growth rate under ambient O 2 was 0.60 ± 0.02 d -1 , which was half of the growth rate during light period and 15-fold of growth rate during dark period. Decreasing O 2 increased the growth rate during light period but decreased it during dark period, and decreased cell pigment content in both the light and dark periods. In the light, low O 2 increased cell carbon (C) content, while hypoxia decreased it, with the degree of increase and decrease being greater in the dark. Low O 2 had no significant effect on cell nitrogen (N) content, but hypoxia decreased it. Low O 2 had no significant effect on photosynthetic efficiency, but decreased the dark respiration rate. In darkness, low O 2 had no significant effect on cell C loss rate, but decreased N loss rate, leading to an increase in the POC:PON ratio. In addition, hypoxia exacerbated the cell mortality and sinking, suggesting that diatomderived carbon burial may be accelerated due to marine deoxygenation in the future.

    Keywords: lowering O 2, Light and dark, diatom, Cell composition, Sinking rate

    Received: 19 Nov 2024; Accepted: 15 Jan 2025.

    Copyright: © 2025 Chen, Song, Xu, Ji, Yang and Li. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Hui Song, Shandong University, Jinan, China
    Gang Li, Daya Bay Marine Biology Research Station, Chinese Academy of Sciences, Shenzhen, China

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