Part two of a two part talk describing a remarkable event that occurred in the Arctic 50 million years ago, when a unique floating freshwater plant called Azolla repeatedly covered the surface of the ocean for almost a million years. Due to its phenomenal growth, Azolla sequestered enormous quantities of the greenhouse gas carbon dioxide, and changed the Earth's climate from a greenhouse world towards our modern icehouse climate with its permanent ice and snow at both poles. 'The Arctic Azolla Event' was discovered by the Arctic Coring Expedition (ACEX) when it recovered sediments beneath the North Pole in 2004. The discovery was featured in the New York Times (November 20, 2004) and National Geographic (May 2005), and its validity has now been confirmed by international teams of scientists who have investigated and published on the cores, including a series of papers in the scientific journal ‘Nature’.

1. THE AZOLLA STORY
HOW AN AMAZING PLANT CHANGED
OUR CLIMATE 50 MILLION YEARS AGO
(SECOND HALF OF THE TALK)
DR JONATHAN BUJAK

2. PART 5
the Arctic Coring Expedition (ACEX)

3. IODP Leg 302 aka the Arctic Coring Expedition (ACEX)
the drillship Vidar Viking sailed into the Arctic
supported by Norwegian and Russian icebreakers

4. ACEX was a great success
It cored the
Lomonosov Ridge
close to the North Pole
ACEX
Lomonosov Ridge
North Pole
ACEX

5. …..recovering
420m of cored section
including the crucial
50 million year old interval
when CO2 fell so abruptly

6. and the results
amazed everyone!

7. more than 90% of the
50 million year old section
was filled with the
remains of Azolla

8. and the Azolla fossils
occur as undisturbed
laminated layers

9. mudstone layer
Azolla layer
Azolla layer
layers of undisturbed Azolla remains that gently sank to the sea floor

10. and they also occur within
a succession of marine rocks….

11. …..but Azolla is a freshwater plant
how could it grow
in the middle of the Arctic Ocean?

12. what do we know about Azolla?

13. PART 6
we meet Azolla

14. Azolla is a floating aquatic freshwater fern
the oldest 70 million year old fossils from the Late Cretaceous have identical
morphology to modern forms indicating similar biology and habitat

15. they have small spongy leaves
and tendrils dangling beneath the leaves in the water

16. Azolla is one of the fastest growing plant on the planet
doubling its biomass in just 2 to 3 days

17. and it is widely used in the Far East
as a green biofertilizer to increase rice production

18. Azolla being grown outdoors in India for cattle fodder
as well as a livestock feed in India and the Far East

19. but why is it used as a biofertilizer?

20. and how can it grow so rapidly free-floating
on water without any nutrients from the soil?

21. the key is Azolla’s
leaf structure

22. Azolla’s leaves
contain cavities that are
filled with nitrogen
source: Carrapiço, 2002

23. these provide an enclosed
micro-environment
for the nitrogen-fixing
cyanobacterium Anabaena
source: Carrapiço, 2002

24. enabling the two organisms to have a mutually beneficial symbiosis
Azolla provides a home for the cyanobacterium Anabaena
which sequesters the nitrogen needed to fertilize Azolla
nitrogen
micro-environment

25. Azolla’s sporophyte
sporocarps
megasporocarp
megasporocarp’s chamber
megasporocarp’s chamber
fertilization
new sporophyte
and the two organisms remain together during Azolla’s reproductive cycle
so that Anabaena is passed to successive generations via Azolla’s spores

26. Azolla’s sporophyte
sporocarps
megasporocarp
megasporocarp’s chamber
megasporocarp’s chamber
fertilization
new sporophyte
with the result that they have co-evolved for more than 70 million years
making the Azolla-Anabaena symbiosis extremely efficient

27. for example, Azolla and Anabaena have complementary photosynthesis
and are therefore able to utilize light from most of the visible spectrum
Azolla contains chlorophyll-a,
chlorophyll-b and coratinoids
whereas Anabaena contains
chlorophyll-a, phycocyanin,
allophycocyanin and phycoerythrin

28. Azolla-Anabaena is the only known symbiosis in which
the two organisms remain together during the plant’s reproductive cycle
and it was designated a ‘Superorganism’
by Francisco Carrapiço in 2009 *
* Carrapiço, F. 2009. ‘Azolla as a superorganism. Its implication in the symbiotic studies’. In: “Stress Biology”. Seckbach, J. and Grube, M. (Eds). Springer.

29. cyanobacteria were widespread three billion years ago when the Earth’s atmosphere
was devoid of oxygen – but they had to go ‘underground’ and colonize
anaerobic enviroments when the atmosphere became oxygenated
stromatolites composed of cyanobacteria three billion years ago

30. Azolla and Anabaena established their symbiotic relationship 70 million years ago –
the oldest evidence is from the Cretaceous Bearpaw Formation of the
Canadian Mackenzie Delta which was characterized by subtropical swamps

31. dinosaurs rummaging in the soil may have
inadvertently triggered the original symbiosis –
the most successful plant-cyanobacterial
partnership that is know today

32. resulting in Azolla-Anabaena’s ability
to fix more than 1000 kg of
atmospheric nitrogen per acre per year *
providing a natural biofertilizer in the water
for rice production
* Barke et al. unpublished data

33. with the nitrogen becoming
available for rapid growth of Azolla
which can then fix up to 6000 kg
of atmospheric carbon per acre per year *
free-floating on water
* unpublshed data, various sources

34. recent studies also show that
• Azolla can tolerate salinities of up to 5 psu **
(practical salinity units)
• Azolla’s optimum growth is in 20 hours of daylight *
• and its growth is increased by elevated CO2 **
*Barke et al. in press; **Speelman et al. (2009)

35. so how does this relate
to Arctic events 50 million years ago?

36. PART 7
THE ARCTIC AZOLLA EVENT

37. during the Paleocene and early Eocene the Arctic Ocean had an
open marine connection to the Tethyan Ocean via the Turgay Strait
illustration from Barke & Bujak, NATURE, in press

38. but the connection was severed when the strait closed due to
tectonic uplift at the end of the early Eocene 50 million years ago
50 Ma
illustration from Barke & Bujak, NATURE, in press

39. resulting in enclosure of the Arctic Ocean,
basin stratification and bottom-water anoxia
50 Ma
illustration from Barke & Bujak, NATURE, in press

40. similar to today’s Black Sea
illustration from Barke & Bujak, NATURE, in press

41. today’s Arctic Ocean has relatively low salinity compared to the world’s oceans

42. due to freshwater input from its large catchment area…..

43. …..and 50 million years ago higher temperatures and rainfall increased river discharge
resulting in surface freshwater plumes and low salinity across the basin
illustration from Barke & Bujak, NATURE, in press

44. with a net runoff into the Arctic Ocean estimated
at 15 million cubic kilometres per year
Source: Speelman (2010)

45. this freshened surface waters across the entire Arctic Ocean
to values of 0 to 6 psu*
overlapping Azolla’s maximum salinity tolerance of 5 psu**
* Barke & Bujak (in press); ** Speelman (2010)
Azolla

46. so Azolla was able to rapidly spread across the surface
of the Arctic Ocean due to its symbiosis with Anabaena…..
Azolla

47. CO2 drawdown
…..Anabaena provided the nitrogen needed to fertilize Azolla
enabling it to sequester large volumes of CO2 into its plant biomass

48. and bottom-water anoxia resulted in the absence of benthic organisms
that normally recycle organic material up through the water column
anoxia

49. so that the Azolla plants with their sequestered CO2
were deposited on the sea floor as a succession of
undisturbed laminated sediments

50. local anoxia
geochemical studies indicate that the Azolla interval
is a petroleum source rock that may extend beneath the entire Arctic Ocean*
CO2 drawdown
petroleum source rock
* Ruediger Stein, Alfred Wegener Institute, 2006

51. local anoxiapetroleum source rock
…..so that Azolla has the potential to provide
a gas-prone source of energy beneath Arctic

52. and a biofuel from modern Azolla

53. the Azolla event lasted for almost a million years
It ended when the Turgay Strait re-opened
providing us with an model for the Azolla Event
illustration from Barke & Bujak, NATURE, in press

54. 50 million years ago
Azolla sequestered
enormous quantities
of atmospheric carbon

55. triggering
the onset
of climatic
cooling

56. which resulted in today’s icehouse world
with glaciation at both poles
as atmospheric CO2 progressively fell…..

57. during the Azolla event (50 Ma)

58. though the Miocene (14 Ma)

59. into the Pliocene (2 Ma)

60. and the Pleistocene - including the Last Glacial Maximum (14,000 BP)

61. and today’s Holocene interglacial…..

62. …..as featured in National Geographic May 2005
“The Great Green North: Was the icy Arctic once a warm soup of life?”
Azolla

63. as well as NATURE
June 2006
“The Cenozoic Arctic Ocean:
from greenhouse to icehouse
in 55 million years” *
* Brinkhuis, Bujak et al., 2006

64. …..and the New York Times in November 2004
Need a picture of NYT page

65. So did a single plant called Azolla
really change the Earth’s climate from a
greenhouse to icehouse state?

66. the answer has implications for past
and present climate change
which is crucially important today

67. Contact Dr Jonathan Bujak
for more details about modern and fossil Azolla
and its potential to help us
mitigate climate change today
info@azollabiosystems.co.uk