Carbon geochemistry of plankton-dominated samples in the Laptev and East Siberian shelves: Contrasts in suspended particle composition

Tommaso Tesi*, Marc C. Geibel, Christof Pearce, Elena Panova, Jorien E. Vonk, Emma Karlsson, A. Joan Salvado, Martin Krusä, Lisa Bröder, Christoph Humborg, Igor P. Semiletov, Örjan Gustafsson

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


Recent Arctic studies suggest that sea ice decline and permafrost thawing will affect phytoplankton dynamics and stimulate heterotrophic communities. However, in what way the plankton composition will change as the warming proceeds remains elusive. Here we investigate the chemical signature of the plankton-dominated fraction of particulate organic matter (POM) collected along the Siberian Shelf. POM (> 10μm) samples were analysed using molecular biomarkers (CuO oxidation and IP25) and dual-carbon isotopes (δ13C and Δ14C). In addition, surface water chemical properties were integrated with the POM (< 10μm) dataset to understand the link between plankton composition and environmental conditions. ä13C and 114C exhibited a large variability in the POM (< 10μm) distribution while the content of terrestrial biomarkers in the POM was negligible. In the Laptev Sea (LS), (δ13C and Δ14C) of POM (< 10μm) suggested a heterotrophic environment in which dissolved organic carbon (DOC) from the Lena River was the primary source of metabolisable carbon. Within the Lena plume, terrestrial DOC probably became part of the food web via bacteria uptake and subsequently transferred to relatively other heterotrophic communities (e.g. dinoflagellates). Moving eastwards toward the sea-ice-dominated East Siberian Sea (ESS), the system became progressively more autotrophic. Comparison between δ13C of POM (< 10μm) samples and CO2aq concentrations revealed that the carbon isotope fractionation increased moving towards the easternmost and most productive stations. In a warming scenario characterised by enhanced terrestrial DOC release (thawing permafrost) and progressive sea ice decline, heterotrophic conditions might persist in the LS while the nutrient-rich Pacific inflow will likely stimulate greater primary productivity in the ESS. The contrasting trophic conditions will result in a sharp gradient in δ13C between the LS and ESS, similar to what is documented in our semi-synoptic study.

Original languageEnglish
Pages (from-to)735-748
Number of pages14
JournalOcean Science
Issue number5
Publication statusPublished - 18 Sept 2017


Acknowledgements. We thank the I/B Oden crew and the Swedish Polar Research Secretariat staff. This study was supported by the Knut and Alice Wallenberg Foundation (KAW contract 2011.0027), the Swedish Research Council (VR contract 621-2007-4631 and 621-2013-5297) and the European Research Council (ERC-AdG CC-TOP project #695331 to Örjan Gustafsson). Tommaso Tesi additionally acknowledges EU financial support as Marie Curie fellow (contract no. PIEF-GA-2011-300259). Joan A. Salvado acknowledges EU financial support through a Marie Curie grant (contract no. FP7-PEOPLE-2012-IEF; project 328049). Igor Semiletov acknowledges financial support from the Russian Government (grant no. 14, Z50.31.0012/03.19.2014) and the Russian Foundation for Basic Research (nos. 13-05-12028 and 13-05-12041), and Elena Panova from the Russian Scientific Foundation (grant no. 15-17-20032). We thank the Arctic Great Rivers Observatory (NSF-1107774) for providing DOC and POC river data ( This is ISMAR publication ID n.1940.

FundersFunder number
Russian GovernmentZ50.31.0012/03.19.2014
Russian Scientific Foundation15-17-20032
Seventh Framework Programme300259, 328049, 695331
Marie CurieFP7-PEOPLE-2012-IEF, PIEF-GA-2011-300259
European Commission
European Research Council
Russian Foundation for Basic Research13-05-12041, 13-05-12028
Knut och Alice Wallenbergs Stiftelse
Vetenskapsrådet621-2007-4631, 621-2013-5297


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