| |
| |
|
|
|
|
| |
 |
Biogeochemistry in oligotrophic ocean gyres
|
| |
|
|
Correlation analyses of marine nitrogen fixers and dissolved iron in the global ocean
P-M2-08-S
Zuo Haoyue* , Zhejiang University
Presenter Email: 3150100177@zju.edu.cn |
| Iron (Fe) is a widely hypothesized limiting factor on the marine nitrogen fixation. In this study, we analyzed the relationship between abundance of nitrogen fixers (diazotroph) and Fe concentration in the global ocean. Both modeled (CESM) and in-situ measured Fe concentration was used in this study. NifH-gene copies were used to represent diazotroph abundance, including those of Trichodesmium, unicellular cyanobacteria (UCYN) groups A, B and C, and heterocystous groups (Richelia and Calothrix). The diazotroph biomass was also estimated from nifH copies. Simple linear regression was conducted between Fe concentration and these 7 variables. Contradictory to the previous hypothesis, most of our results using global ocean data do not reveal positive correlations between diazotroph and Fe concentration. Trichodesmium nifH, UCYN-B nifH and total diazotrophic biomass even had negative relationships with modeled Fe. Only UCYN-C nifH abundance in surface 50 m showed positive correlation with measured Fe concentration data. Analyses in North Atlantic often showed weak correlation between diazotrophs and Fe, except for Trichodesmium nifH and total diazotrophic biomass which had negative correlations with modeled Fe. In Pacific, analyses usually revealed strong negative correlations between modeled Fe and diazotrophs, except for UCYN-A nifH which had positive correlation with Fe. Our study raise a question whether Fe limits growth of diazotrophs in the real marine environment. |
|
|
|
|
|
|
|
|