Turn off MathJax
Article Contents
Hua Wang, Ya-Wei Luo. Top-down control on major groups of global marine diazotrophs[J]. Acta Oceanologica Sinica. doi: 10.1007/s13131-021-1956-2
Citation: Hua Wang, Ya-Wei Luo. Top-down control on major groups of global marine diazotrophs[J]. Acta Oceanologica Sinica. doi: 10.1007/s13131-021-1956-2

Top-down control on major groups of global marine diazotrophs

doi: 10.1007/s13131-021-1956-2
Funds:  The National Natural Science Foundation of China under contract Nos 41890802 and 42076153.
More Information
  • Corresponding author: E-mail: ywluo@xmu.edu.cn
  • Received Date: 2021-07-16
  • Accepted Date: 2021-10-20
  • Available Online: 2022-04-14
  • Di-nitrogen (N2) fixed by a group of prokaryotes (diazotrophs) is the dominant process adding bioavailable nitrogen into the ocean. Although it has been intensively studied how N2 fixation is controlled by resources (bottom-up factors), it is unclear whether the grazing (top-down control) effectively impact growth and distribution of different diazotroph groups. In this study, we evaluate this question by conducting log-log regression of diazotroph biomass onto corresponding N2 fixation rates in the global ocean. The slope of regression for Trichodesmium is ~0.8, indicating that a small portion of the increase of N2 fixation does not accumulate as its biomass. That leads to a conclusion that Trichodesmium is under a substantial top-down control, although bottom-up control still dominates. We also analyze the residuals of the regression in the North Atlantic, concluding that free trichomes of Trichodesmium is subject to stronger top-down control than its colonies. The weak correlation between the biomass and N2 fixation of unicellular cyanobacterial diazotrophs indicates that the degree of top-down control on this type of diazotrophs varies greatly. The analyses obtain unrealistic results for diatom-diazotroph assemblages due to complicate nitrogen sources of these symbioses. Our study reveals the variability of top-down control among different diazotroph groups across time and space, suggesting its importance in improving our understandings of ecology of diazotrophs and predictions of N2 fixation in biogeochemical models. Measurements of size-specific N2 fixation rates and growth rates of different diazotroph groups can be useful to more reliably analyze the top-down control on these key organisms in the global ocean.
  • loading
  • 加载中

Catalog

    通讯作者: 陈斌, bchen63@163.com
    • 1. 

      沈阳化工大学材料科学与工程学院 沈阳 110142

    1. 本站搜索
    2. 百度学术搜索
    3. 万方数据库搜索
    4. CNKI搜索

    Article Metrics

    Article views (109) PDF downloads(15) Cited by()
    Proportional views
    Related

    /

    DownLoad:  Full-Size Img  PowerPoint
    Return
    Return