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Alkenone Distributions and Hydrogen Isotope Ratios Show Changes in Haptophyte Species and Source Water in the Holocene Baltic Sea

Weiss, Gabriella M. and Massalska, Barbara and Hennekam, Rick and Reichart, Gert‐Jan and Damsté, Jaap S. Sinninghe and Schouten, Stefan and Van der Meer, Marcel T. J. (2020) Alkenone Distributions and Hydrogen Isotope Ratios Show Changes in Haptophyte Species and Source Water in the Holocene Baltic Sea. Geochemistry, Geophysics, Geosystems, 21 (2). Art. No. e2019GC008751. ISSN 1525-2027. doi:10.1029/2019gc008751.

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The Baltic Sea, a dynamic, marginal marine basin, experienced a number of large changes in salinity during the Holocene as a result of fluctuations in global and local sea level related to melting of glacial ice sheets and subsequent isostatic rebound. These changes likely had pronounced effects on the species composition of haptophytes, a common phytoplankton group found in the Baltic Sea. This dynamic environment provides the ideal setting to study how species change impacts distribution and hydrogen isotope ratios of long‐chain alkenones (δ²H_(C37)), haptophyte‐specific biomarkers. Here we analyzed the aforementioned parameters in Holocene sediments covering the contrasting hydrological phases of the Baltic Sea. Alkenone distributions changed with different Baltic Sea salinity phases, suggesting that species shifts coincide with salinity change. δ²H_(C37) values show two major shifts: one in the middle of the freshwater Ancylus Lake phase (10.6 to 7.7 ka) and a second at the transition from the brackish Littorina Sea phase (7.2 to 3 ka) into the fresher Modern Baltic (3 ka to the present). The first shift represents a significant enrichment of 50‰, which cannot be explained by salinity or species changes only. At this time, the isotopically depleted ice sheets had melted, and only the relatively enriched freshwater source remained. The second shift, coincident with a change in distribution, is likely caused by a change in species composition alone. These findings show that hydrogen isotope ratios of long‐chain alkenones, combined with their relative distribution, can be used to reconstruct changes in source water.

Item Type:Article
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URLURL TypeDescription ItemData
Weiss, Gabriella M.0000-0002-9571-2558
Hennekam, Rick0000-0002-8823-4519
Reichart, Gert‐Jan0000-0002-7256-2243
Additional Information:© 2020 The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Received 10 OCT 2019; Accepted 17 JAN 2020; Accepted article online 08 FEB 2020. The captain and crew of the RV Pelagia are thanked for their help with obtaining the piston core used in the present investigation. We thank Editor Adina Paytan, Dr. Jaime Toney, and an anonymous reviewer for their comments which improved the manuscript. This study received funding from the Netherlands Earth System Science Center (NESSC) though a Gravitation grant (024.002.001) from the Dutch Ministry for Education, Culture and Science. All acquired data are stored in the Royal Netherlands Institute for Sea Research (NIOZ) database which can be accessed at (DOI: 10.25852/nioz/7b.b.q).
Funding AgencyGrant Number
Netherlands Earth System Science Center024.002.001
Ministerie van Onderwijs, Cultuur en WetenschappenUNSPECIFIED
Subject Keywords:hydrogen isotopes; alkenones; haptophytes; Baltic Sea
Issue or Number:2
Record Number:CaltechAUTHORS:20200408-151648418
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Official Citation:Weiss, G. M., Massalska, B., Hennekam, R., Reichart, G.‐J., Sinninghe Damsté, J. S., Schouten, S., & van der Meer, M. T. J. (2020). Alkenone distributions and hydrogen isotope ratios show changes in haptophyte species and source water in the Holocene Baltic Sea. Geochemistry, Geophysics, Geosystems, 21, e2019GC008751.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102411
Deposited By: Tony Diaz
Deposited On:08 Apr 2020 22:52
Last Modified:16 Nov 2021 18:11

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