Coeval Eocene blooms of the freshwater fern Azolla in and around Arctic and Nordic seas

Judith Barke; Johan van der Burgh; Johanna H.A. van Konijnenburg-van Cittert; Margaret E. Collinson; Martin A. Pearce; Jonathan Bujak; Claus Heilmann-Clausen; Eveline N. Speelman; Monique M.L. van Kempen; Gert-Jan Reichart; André F. Lotter; Henk Brinkhuis

doi:10.1016/j.palaeo.2012.04.002

Coeval Eocene blooms of the freshwater fern Azolla in and around Arctic and Nordic seas

Judith Barke, Johan van der Burgh, Johanna H.A. van Konijnenburg-van Cittert^*, Margaret E. Collinson, Martin A. Pearce, Jonathan Bujak, Claus Heilmann-Clausen, Eveline N. Speelman, Monique M.L. van Kempen, Gert-Jan Reichart, André F. Lotter, Henk Brinkhuis

^*Corresponding author for this work

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

For a short time interval (c. 1.2. Myr) during the early middle Eocene (~. 49. Myr), the central Arctic Ocean was episodically densely covered by the freshwater fern Azolla, implying sustained freshening of surface waters. Coeval Azolla fossils in neighboring Nordic seas were thought to have been sourced from the Arctic. The recognition of a different Azolla species in the North Sea raised doubts about this hypothesis. Here we show that no less than five Azolla species had coeval blooms and spread in the Arctic and NW European regions. A likely trigger for these unexpected Azolla blooms is high precipitation prevailing by the end of the warmest climates of the Early Eocene Climatic Optimum (EECO).

Original language	English
Pages (from-to)	108-119
Number of pages	12
Journal	Palaeogeography, Palaeoclimatology, Palaeoecology
Volume	337-338
DOIs	https://doi.org/10.1016/j.palaeo.2012.04.002
Publication status	Published - 15 Jun 2012

Funding

We thank L. Bik and N. Welters for their great support. We would like to thank J. van Tongeren in Utrecht and B.J. van Heuven in Leiden for technical support with the SEM work; and T. Brain in Kings College London for his extensive support with both TEM and SEM work during this study. We thank Nora Radionova for discussion of the palaeogeography of Western Siberia. JB thanks Arthur R. Sweet for many fruitful discussions. The samples and accompanying data for Azolla arctica ( Collinson et al., 2009 ), were provided by the Integrated Ocean Drilling Program (IODP). We thank Statoil and the Canadian Geological Survey for providing samples for this study. We thank the Darwin Centre , LPP Foundation and Statoil for their financial support.

Keywords

Arctic ocean
Azolla
Early middle eocene
EECO (early eocene climatic optimum)
Fresh ocean surface waters
Nordic seas

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10.1016/j.palaeo.2012.04.002

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Barke, J., van der Burgh, J., van Konijnenburg-van Cittert, J. H. A., Collinson, M. E., Pearce, M. A., Bujak, J., Heilmann-Clausen, C., Speelman, E. N., van Kempen, M. M. L., Reichart, G.-J., Lotter, A. F., & Brinkhuis, H. (2012). Coeval Eocene blooms of the freshwater fern Azolla in and around Arctic and Nordic seas. Palaeogeography, Palaeoclimatology, Palaeoecology, 337-338, 108-119. https://doi.org/10.1016/j.palaeo.2012.04.002

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abstract = "For a short time interval (c. 1.2. Myr) during the early middle Eocene (~. 49. Myr), the central Arctic Ocean was episodically densely covered by the freshwater fern Azolla, implying sustained freshening of surface waters. Coeval Azolla fossils in neighboring Nordic seas were thought to have been sourced from the Arctic. The recognition of a different Azolla species in the North Sea raised doubts about this hypothesis. Here we show that no less than five Azolla species had coeval blooms and spread in the Arctic and NW European regions. A likely trigger for these unexpected Azolla blooms is high precipitation prevailing by the end of the warmest climates of the Early Eocene Climatic Optimum (EECO).",

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doi = "10.1016/j.palaeo.2012.04.002",

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Barke, J, van der Burgh, J, van Konijnenburg-van Cittert, JHA, Collinson, ME, Pearce, MA, Bujak, J, Heilmann-Clausen, C, Speelman, EN, van Kempen, MML, Reichart, G-J, Lotter, AF & Brinkhuis, H 2012, 'Coeval Eocene blooms of the freshwater fern Azolla in and around Arctic and Nordic seas', Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 337-338, pp. 108-119. https://doi.org/10.1016/j.palaeo.2012.04.002

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AU - Barke, Judith

AU - van der Burgh, Johan

AU - van Konijnenburg-van Cittert, Johanna H.A.

AU - Collinson, Margaret E.

AU - Pearce, Martin A.

AU - Bujak, Jonathan

AU - Heilmann-Clausen, Claus

AU - Speelman, Eveline N.

AU - van Kempen, Monique M.L.

AU - Reichart, Gert-Jan

AU - Lotter, André F.

AU - Brinkhuis, Henk

PY - 2012/6/15

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AB - For a short time interval (c. 1.2. Myr) during the early middle Eocene (~. 49. Myr), the central Arctic Ocean was episodically densely covered by the freshwater fern Azolla, implying sustained freshening of surface waters. Coeval Azolla fossils in neighboring Nordic seas were thought to have been sourced from the Arctic. The recognition of a different Azolla species in the North Sea raised doubts about this hypothesis. Here we show that no less than five Azolla species had coeval blooms and spread in the Arctic and NW European regions. A likely trigger for these unexpected Azolla blooms is high precipitation prevailing by the end of the warmest climates of the Early Eocene Climatic Optimum (EECO).

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ER -

Coeval Eocene blooms of the freshwater fern Azolla in and around Arctic and Nordic seas

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