The Eocene Arctic Azolla bloom: environmental conditions, productivity and carbon drawdown.

@article{Speelman2009TheEA,
  title={The Eocene Arctic Azolla bloom: environmental conditions, productivity and carbon drawdown.},
  author={Eveline N. Speelman and M M L van Kempen and Judith Barke and Henk Brinkhuis and Gert‐Jan Reichart and Alfons J. P. Smolders and Jan G. M. Roelofs and Francesca Sangiorgi and Jan Willem de Leeuw and Andr{\'e} F. Lotter and J. Sinninghe Damst{\'e}},
  journal={Geobiology},
  year={2009},
  volume={7 2},
  pages={
          155-70
        }
}
Enormous quantities of the free-floating freshwater fern Azolla grew and reproduced in situ in the Arctic Ocean during the middle Eocene, as was demonstrated by microscopic analysis of microlaminated sediments recovered from the Lomonosov Ridge during Integrated Ocean Drilling Program (IODP) Expedition 302. The timing of the Azolla phase (approximately 48.5 Ma) coincides with the earliest signs of onset of the transition from a greenhouse towards the modern icehouse Earth. The sustained growth… 
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Did a single species of Eocene Azolla spread from the Arctic Basin to the southern North Sea
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The salt resistance limit of 90 mM NaCl corresponds well to climate model predictions of salinity levels of ancestral habitats of Azolla in the Eocene Arctic Ocean and can therefore be used to predict the tipping point concentration.
Coeval Eocene blooms of the freshwater fern Azolla in and around Arctic and Nordic seas
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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
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The salt resistance limit of 90 mM NaCl corresponds well to climate model predictions of salinity levels of ancestral habitats of Azolla in the Eocene Arctic Ocean and can therefore be used to predict the tipping point concentration.
Evidence from shark teeth for a brackish Arctic Ocean in the Eocene greenhouse
Temperatures are rising at an unprecedented rate in the Arctic, and affecting the sensitive hydrological cycle with increased freshwater inputs to the marine environment. A deep-time analogue often
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A Siliceous Microfossil View of Middle Eocene Arctic Paleoenvironments
Integrated Ocean Drilling Program (IODP) Expedition 302, “The Arctic Coring Expedition” (ACEX), unearthed the most significant find of Paleogene siliceous microfossils in nearly 2 decades. 100 m of
Episodic fresh surface waters in the Eocene Arctic Ocean
TLDR
Palaeogene sediments obtained during the Arctic Coring Expedition are analysed, showing that large quantities of the free-floating fern Azolla grew and reproduced in the Arctic Ocean by the onset of the middle Eocene epoch and that onset and termination of the Azolla phase depended on the degree of oceanic exchange between Arctic Ocean and adjacent seas.
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We have reconstructed the surface water environment of the Arctic Ocean over the last ∼ 50,000 years using measurements of the organic nitrogen and carbon isotope ratios, carbonate and total organic
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TLDR
It would appear that atmospheric CO 2 enrichment may be capable of preventing the deaths of some plant species in situations where their demise is normally brought about by either the direct effects of unduly high temperatures or by associated debilitating diseases.
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Eocene bipolar glaciation associated with global carbon cycle changes
The transition from the extreme global warmth of the early Eocene ‘greenhouse’ climate ∼55 million years ago to the present glaciated state is one of the most prominent changes in Earth's climatic
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TLDR
Eocene sediments recovered from the Lomonosov Ridge in the central Arctic Ocean contain high amounts of fossil remains of the free floating freshwater fern Azolla, and a suite of long-chain, mid-chain ω20 hydroxy wax constituents is described for the first time.
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TLDR
Direct measurements of 15N2 fixation by small diazotrophs in various parts of the Pacific Ocean, including the waters off Hawaii where the unicellular diazOTrophs were first characterized, show that N1 fixation by unicells can support a significant fraction of total new production in oligotrophic waters.
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