This preprint is currently under review for the journal BG.
Impact of metabolic pathways and salinity on the hydrogen isotope ratios of haptophyte lipids
Gabriella M. Weiss1,David Chivall1,a,Sebastian Kasper1,Hideto Nakamura2,3,b,Fiz da Costa4,c,Philippe Soudant4,Jaap S. Sinninghe Damsté1,5,Stefan Schouten1,5,and Marcel T. J. van der Meer1Gabriella M. Weiss et al. Gabriella M. Weiss1,David Chivall1,a,Sebastian Kasper1,Hideto Nakamura2,3,b,Fiz da Costa4,c,Philippe Soudant4,Jaap S. Sinninghe Damsté1,5,Stefan Schouten1,5,and Marcel T. J. van der Meer1
1Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research and Utrecht University, Den Burg, the Netherlands
2Department of Earth and Planetary Sciences, Faculty of Science, Hokkaido University, N10W8, Kita-ku, Sapporo 060-0810, Japan
3CREST, Japan Science and Technology Agency (JST), N10W8, Kita-ku, Sapporo 060-0810, Japan
4Laboratoire des Sciences de l'Environnement Marin (LEMAR UMR 6539CNRS/UBO/IRD/Ifremer), IUEM, rue Dumont d’Urville, 29280 Plouzané, France
5Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, the Netherlands
apresent address: Oxford Radiocarbon Accelerator Unit, University of Oxford, Oxford OX1 3TG, UK
bpresent address: Department of Biology and Geosciences, Osaka City University, Sugimoto 3-3-138, Sumiyoshi-ku, Osaka, 558-8585, Japan
cpresent address: Centro de Investigación Mariña, Universidade de Vigo,Illa de Toralla s/n, 36331, Vigo, Spain
1Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research and Utrecht University, Den Burg, the Netherlands
2Department of Earth and Planetary Sciences, Faculty of Science, Hokkaido University, N10W8, Kita-ku, Sapporo 060-0810, Japan
3CREST, Japan Science and Technology Agency (JST), N10W8, Kita-ku, Sapporo 060-0810, Japan
4Laboratoire des Sciences de l'Environnement Marin (LEMAR UMR 6539CNRS/UBO/IRD/Ifremer), IUEM, rue Dumont d’Urville, 29280 Plouzané, France
5Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, the Netherlands
apresent address: Oxford Radiocarbon Accelerator Unit, University of Oxford, Oxford OX1 3TG, UK
bpresent address: Department of Biology and Geosciences, Osaka City University, Sugimoto 3-3-138, Sumiyoshi-ku, Osaka, 558-8585, Japan
cpresent address: Centro de Investigación Mariña, Universidade de Vigo,Illa de Toralla s/n, 36331, Vigo, Spain
Abstract. Hydrogen isotope ratios of biomarkers have been shown to reflect water isotope ratios, and in some cases correlate significantly with salinity. The δ2H-salinity relationship is best studied for long-chain alkenones, biomarkers for haptophyte algae, and is known to be influenced by a number of different environmental parameters. It is not fully known why δ2H ratios of lipids retain a correlation to salinity, and whether this is a general feature for other lipids produced by haptophyte algae. Here, we analyzed δ2H ratios of three fatty acids, brassicasterol, long-chain C37 alkenones and phytol from three different haptophyte species grown over a range of salinities. Lipids synthesized in the cytosol, or relying on precursors of cytosolic origin, show a correlation between their δ2H ratios and salinity. In contrast, biosynthesis in the chloroplast, or utilizing precursors created in the chloroplast, yields lipids that do not show a correlation between δ2H ratios and salinity. This leads to the conclusion that location of metabolism is the first-order control on the salinity signal retained in δ2H ratios of certain lipids. Additionally, we found that δ2H ratios of alkenones from batch cultures of the Group II haptophyte species Tisochrysis lutea correlate positively with temperature, contrary to findings from cultures of Group III haptophytes, but retain a similar response to nutrient availability in line with other Group III haptophytes.
In this study, we used four different haptophyte species and six different organic compounds to investigate the relationship between organic matter synthesis and salinity. We showed that creation in different parts of the cell (chloroplast versus cytosol) determined which compounds retain a correlation between their hydrogen isotopes and salinity. This is important for using hydrogen isotopes to reconstruct salinity in the geologic record.
In this study, we used four different haptophyte species and six different organic compounds to...
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