Surface South Pacific ecosystems reflect the availability of the nutrients iron, nitrate and phosphate

Thanks to a high resolution section across the South Pacific (150°E-150°W, GEOTRACES GP13 cruise), Ellwood and co-workers (2018, see reference below) identify that the gradient of sources and fates of the 3 nutrients iron (Fe), nitrogen (N) and phosphorus (P) is explaining the observed ecosystem west-east gradient. In the west, phytoplankton able to fix atmospheric nitrogen (diazotroph species) is abundant while it is the opposite in the eastern end of the section. As shown in the figure, such drop of the diazotroph species is due to the low abundance of Fe in the most remote part of the section.

18 Ellwood figure

Figure: Cartoon showing the input fluxes for iron (Fe), nitrogen (N) and phosphorus (P) into surface ocean across the GP13 zonal section. In the west, diazotrophs are abundant while it is the opposite in the eastern end of the section due to the low abundance of Fe, in the most remote part of the section. Click here to view the figure larger.

Reference:

Ellwood, M. J., Bowie, A. R., Baker, A., Gault-Ringold, M., Hassler, C., Law, C. S., Maher, W. A., Marriner, A., Nodder, S., Sander, S., Stevens, C., Townsend, A., van der Merwe, P., Woodward, E. M. S., Wuttig, K., Boyd, P. W. (2018). Insights Into the Biogeochemical Cycling of Iron, Nitrate, and Phosphate Across a 5,300 km South Pacific Zonal Section (153°E-150°W). Global Biogeochemical Cycles, 32(2), 187–207. http://doi.org/10.1002/2017GB005736

Latest highlights

A detailed investigation of iron complexation by organic ligands in the Western Tropical South Pacific Ocean

Léo Mahieu and his co-workers present the conditional concentration and binding-strength of iron-binding ligands during the GEOTRACES TONGA cruise.

New algorithm unclogs major bottleneck in ocean geochemical and biogeochemical modelling

Numerical models are some of the principal tools for understanding the cycling of geochemical and biogeochemical tracers in the ocean…

The tumultuous life of the Antarctic Circumpolar Current over 5,3 million years, including focus on the glacial-interglacial forcing!

To reconstruct the strength of the Antarctic Circumpolar Current, the authors used sediment records from the pelagic central and remote South Pacific.

North-South radium-228 section in the Pacific Ocean

Moore and colleagues present results from radium-228 along the U.S. GEOTRACES Pacific Meridional Transect (GP15).

Rechercher