Research
Theme 1
www.darwincenter.nl
Program 1070

The DARWIN Azolla project – (palaeo) ecology and biogeochemistry of the freshwater fern Azolla and its importance in global biogeochemical cycles
Program coordinator(s): Prof. dr. H. Brinkhuis, Prof. dr. A. F. Lotter
Theme(s): 1
Funding date: 11-jan-06

Abstract
Through analysis of unique central Arctic drill cores we have recently shown that enormous quantities of the free floating, freshwater fern Azolla grew and reproduced in situ in the mid Eocene (~48,5 Ma) Arctic Ocean, timed precisely at the junction from Greenhouse to Icehouse Earth. Since extant Azolla ranks among the fastest growing plants of the planet, this phenomenon may have influenced global C, N and P cycles. From a biogeochemical cycling as well as from a global climate change perspective we identify a strong need for better constraining the capability of Azolla as a sink for atmospheric CO2 in a fresh and anoxic Eocene Arctic Ocean, and assess its potential role as a regulator of regional and global nutrient cycles. We thus propose three strongly interrelated topical DARWIN research avenues via: a study of extant Azolla species using experimental approaches involving varying environmental gradients that mimic the Arctic Eocene (PhD, RU Bio) a study into the palaeobotanical, (palaeo)ecological and (palaeo)biogeographical aspects of the Eocene Northern Hemisphere case, and comparison with modern analogues (PhD UU Bio) an overarching study investigating and modeling the biogeochemistry of modern and fossil Azolla (PhD, UU Geo) in relation to global biogeochemical cycles.

This program contains the following projects:
1071: Subproject 1, the ecophysiological (actuo) component
1072: Subproject 2, the palaeoecological component
1073: Subproject 3, the biogeochemical component

Publications
Speelman, E.N., van Kempen, M.M.L., Barke, J., Brinkhuis, H., Reichart, G.J., Smolders, A.J.P., Roelofs, J.G.M., Sangiorgi, F., de Leeuw, J.W., Lotter, A.F., Sinninghe Damsté, J.S. (2009). The Eocene Arctic Azolla bloom: environmental conditions, productivity and carbon drawdown . Geobiology7 (2): 155-170.
Darwin Center authors: Barke J., Brinkhuis H., van Kempen M. M. L., Lotter A. F., Reichart G. J., Roelofs J. G. M., Sinninghe Damsté J. S., Speelman E. N.

Speelman, E.N., Reichart, G.-J., de Leeuw, J.W., Rijpstra, W.I.C., Sinninghe Damsté, J.S. (2009). Biomarker lipids of the freshwater fern Azolla and its fossil counterpart from the Eocene Arctic Ocean . Organic Geochemistry40 (5): 628-637.
Darwin Center authors: Reichart G. J., Sinninghe Damsté J. S., Speelman E. N.

Margaret E. Collinson, Judith Barke, Johan van der Burgh, Johanna H.A. van Konijnenburg-van Cittert (2009). A new species of the freshwater fern Azolla (Azollaceae) from the Eocene Arctic Ocean. Review of Palaeobotany and Palynology155: 1-14.
Darwin Center authors: Barke J.

Margaret E. Collinson, Judith Barke, Johan van der Burgh, Johanna H.A. van Konijnenburg-van Cittert, Claus Heilmann-Clausen, Lauren E. Howard, Henk Brinkhuis (2010). Did a single species of Eocene Azolla spread from the Arctic Basin to the southern North Sea?. Review of Palaeobotany and Palynology159: 152-165.
Darwin Center authors: Barke J., Brinkhuis H.

Eveline Speelman (2010). Reconstruction of the Arctic Ocean environment during the Eocene Azolla interval using geochemical proxies and climate modeling.
Darwin Center authors: Speelman E. N.

Judith Barke (2010). Palaeoecological and palaeoclimatological implications of the Eocene Northern Hemisphere Azolla phenomenon.
Darwin Center authors: Barke J.

Bauersachs, T., Speelman, E.N., Hopmans, E.C., Reichart, G.J., Schouten, S., Sinninghe Damsté, J.S. (2010). Fossilized glycolipids reveal past oceanic N2 fixation by heterocystous cyanobacteria. Proceedings of the National Academy of Sciences USA (PNAS)107: 19190-19194.
Darwin Center authors: Bauersachs T., Hopmans E. C., Reichart G. J., Schouten S., Sinninghe Damsté J. S., Speelman E. N.

Eveline N. Speelman, Jacob O. Sewall, David Noone, Matthew Huber, Anna von der Heydt, Jaap Sinninghe Damsté, Gert-Jan Reichart (2010). Modeling the influence of a reduced equator-to-pole sea surface temperature gradient on the distribution of water isotopes in the Early/Middle Eocene. Earth and Planetary Science Letters298: 57-65-
Darwin Center authors: Reichart G. J., Sinninghe Damsté J. S., Speelman E. N.

Barke, J., Abels, H.A., Sangiorgi, F., Greenwood, D.R., Sweet, A.R., Donders, T., Reichart, G.-J. , Lotter, A.F., Brinkhuis, H. (2011). Orbitally forced Azolla blooms And Middle Eocene Arctic hydrology: Clues from palynology . GeologyVolume 39, Issue 5: 427-430.
Darwin Center authors: Barke J., Brinkhuis H., Lotter A. F., Reichart G. J.

Monique M.L. van Kempen, Alfons J.P. Smolders, Leon P.M. Lamers and Jan G.M.Roelofs (2012). Micro-Halocline Enabled Nutrient Recycling May Explain Extreme Azolla Event in the Eocene Arctic Ocean. PLOS ONE1-6.
Darwin Center authors: van Kempen M. M. L., Lamers L. P. M., Roelofs J. G. M.

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 (2012). Coeval Eocene blooms of the freshwater fern Azolla in and around Arctic and Nordic seas. Palaeogeography, Palaeoclimatology, Palaeoecology337-338: 108-119.
Darwin Center authors: Barke J., Brinkhuis H., van Kempen M. M. L., Lotter A. F., Reichart G. J., Speelman E. N.

Monique M.L. van Kempena, Alfons J.P. Smolders, Gerard M. Bögemann, Leon L.M. Lamers, Eric J.W. Visser, Jan G.M. Roelofs (2013). Responses of the Azolla filiculoides Stras.–Anabaena azollae Lam. association to elevated sodium chloride concentrations: Amino acids as indicators for salt stress and tipping point. Aquatic Botany106: 20-28.
Darwin Center authors: van Kempen M. M. L., Lamers L. P. M., Roelofs J. G. M.