1. This is a presentation created by Prof. Karen Orcutt (Univ of Southern Mississippi, Dept of Marine Sciences) for the NSTA workshop titled 'COSEE: The Oceans, They Are A-Changin': How Might This Affect You?' on Sat, March 21, 2009. The target audience was middle and high school science educators. Prof. Orcutt focused the often misunderstood concept of nitrogen fixation by open ocean primary producers - in particular the contribution of planktontic filamentous cyanobacteria called Trichodesmium that live in colonies and contribute significantly to the global nitrogen cycle by "fixing" nitrogen gas (N2) into more biologically useful nitrogen-containing compounds (e.g., NH3, ammonia). She also describes the roles of other oceanic biological pump and microbial loop "players" such as heterotrophic bacteria, dinoflagellates and diatoms.

3. Nitrogen Fixation

4. Marine Nitrogen Fixation N 2 + 8H + + 8e - + 16ATP 2NH 3 + H 2 + 16 ADP + 16 P i

5. Important source of N to the oceanImportant source of N to the ocean

6. Marine Nitrogen Fixation N 2 + 8H + + 8e - + 16ATP 2NH 3 + H 2 + 16 ADP + 16 P i Important source of N to the oceanImportant source of N to the ocean Requires energy (P)Requires energy (P) Important source of N to the oceanImportant source of N to the ocean Requires energy (P)Requires energy (P)

7. Marine Nitrogen Fixation N 2 + 8H + + 8e - + 16ATP 2NH 3 + H 2 + 16 ADP + 16 P i Important source of N to the oceanImportant source of N to the ocean Requires energy (P)Requires energy (P) Needs Fe ≈ 34 Fe atomsNeeds Fe ≈ 34 Fe atoms Important source of N to the oceanImportant source of N to the ocean Requires energy (P)Requires energy (P) Needs Fe ≈ 34 Fe atomsNeeds Fe ≈ 34 Fe atoms

8. Puff Tuft T. thiebautii Morphologies of Trichodesmium http://www.whoi.edu/science/B/people/ewebb/Tricho.html

9. Trichodesmium form large surface accumulations that can be seen from ships …. http://www.marine.uq.edu.au/marbot/marineplants/cyanobacteria2.htm http://www.futura-sciences.com/fr/news/t/oceanographie-1/d/les-tresors-biologiques-de- locean_9300/

10. ……and seen from aircraft……..

11. Photo: NASA ……..and from space! Photo NASA

12. Katagnymene pelagicum now Trichodesmium Photo: Annette Hynes

13. Photo: Ed Carpenter Katagnymene spiralis now Trichodesmium

15. Aphanizomenon flos-aquae Nodularia sp. (N. spumigena) N 2 fixation Heterocysts http://www.fimr.fi/en/tietoa/algaline_s euranta/lajistoraportit/lajistoraporttiar kisto/2006/en_GB/3705/ http://www.soes.soton.ac.uk/staff/tt/nf /structure/nodspum.htm

16. Richelia inside Hemiaulus sp. Photo by Dr. Dave Caron

17. Unicellular cyanobacteria nitrogen fixers Crocosphaera watsonii (WH8501) 2-6 µm http://www.whoi.edu /science/B/people/e webb/ Photo Kjell Gundersen

18. Photo: Dr. Frank J. Jochem AGU Ocean Sciences Meeting 2000, San Antonio, Texas, January 2000 Heterotrophic bacteria (  and  -Proteobacteria))

19. Capone 2008

20. CO 2 Deep Surface Bacterial remineralisation Phytoplankton photosynthesis CO 2 + Nutrients CO 2 + Nutrients Fe N P N2N2 © KAREN M. ORCUTT CO 2

21. Diatoms - Bacillariophyceae http://www.olympusmicro.com/primer/technique s/hoffmangallery/diatom.html ASLO image library www.aslo.org

22. Dinoflagelltes - Dinophyceae ASLO image library www.aslo.org http://ux.brookdalecc.edu/staff/sa ndyhook/plankton/summer.htm http://www.biologycorner.com/bio1/no tes_plantlikeprotists.html

23. http://www.whoi.edu/science/B/peopl e/ewebb/Tricho.html

24. NASA/Goddard Space Flight Center The SeaWiFs Project and ORBIMAGE Scientific Visualization Studio.

25. http://cosee.umaine.edu/cfuser/index.cfm