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Biogeochemical Controls and Feedbacks on the Ocean Primary Production

Biogeochemical Controls and Feedbacks on the Ocean Primary Production. Carbon Cycle. Marine Biota. Export Production. Export Production of Organic Carbon. Ocean Ecosystem Structure. Trophic levels and dynamics. Ocean Ecosystem Structure. Example of a more complex Food Web.

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Biogeochemical Controls and Feedbacks on the Ocean Primary Production

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  1. Biogeochemical Controls and Feedbacks on the Ocean Primary Production

  2. Carbon Cycle Marine Biota Export Production

  3. Export Production of Organic Carbon

  4. Ocean Ecosystem Structure Trophic levels and dynamics

  5. Ocean Ecosystem Structure Example of a more complex Food Web

  6. Ocean Ecosystem Structure Energy Transfer between Trophic Levels is not efficient

  7. Trophic levels and dynamics Food Web Energy

  8. ENERGY

  9. How about Mass Transfer?

  10. How do we measure Biomass?

  11. Alaska

  12. Large scale Eddies 200 km

  13. A useful way to keep track of biomass in the lower trophic levels is to follow the path of MACRONUTRIENTS Carbon C Nitrogen N Phosphorus P

  14. Redfield Ratio C : N : P 106 : 16 : 1 Redfield A.C.,On the proportions of organic derivations in seawater and their relation to the composition of plankton. In James Johnson Memorial Volume. (ed. R.J. Daniel). University Press of Liverpool, pp. 177-192.

  15. C : N : P source 1) atmosphere source 1) from N2 atmosphere gas2) ocean subsurface3) remineralization of dead organic matter 4) biological (e.g. excretions) source 1) not biological, not atmospheric2) fluvial Nitrogen appears to be the limiting factorin ocean productivity in todays oceans

  16. A simplified diagram of an NPZD Ecosystem Z P D N

  17. Description of the oceanic ecosystem based on Nitrogen exchanges Fixation N2 Nitrification Mineralization NH4 NO3 Uptake Phytoplankton Grazing Mix Layer depth Chlorophyll Zooplankton Mortality Large detritus Water column Susp. particles Nitrification N2 NH4 NO3 Denitrification Aerobic mineralization Organic matter Sediment

  18. A simplified diagram of an ecosystem

  19. Carbon Cycle Marine Biota Export Production

  20. Export Production of Organic Carbon

  21. A simplified diagram of an ecosystem

  22. What are the controls on Export Production? Nutrient Sources for Primary Production The fluxed of organic carbon must be sustained by an adeguate flux of macronutrients If macronutrients are unavailable then the CO2 flux is reduced!

  23. What are the controls on Export Production? • Ocean nutrient inventory • 2) Utilization of nutrients in HNLC • 3) Change Redfield Ratio

  24. Surface CHL-A 1) Central Gyres 2) Upwelling Regions

  25. What are the controls on Export Production? • Ocean nutrient inventory Nitrogen appears to be the control duringmodern time. (but was not always this way e.g. duringlat glacial maxima)

  26. Modern TIME N2 fixation Denitrification N = 25790 N* = N – 16 P (Gruber & Sarmiento 1997)

  27. What are the controls on Export Production? 2) Utilization of nutrients in HNLC

  28. High Nutrient, Low (Medium) Chlorophyll Regions Why aren’t the nutrients being completely utilized by phytoplankton? Phosphorous Chlorophyll Conkright et al., 1994 µm SeaWiFs

  29. What are the controls on Export Production? 3) Change Redfield Ratio Do not know much about this!

  30. END of Lecture

  31. Southern Ocean HNLC

  32. Biologically Mediated Exchange of CO2 Between the Ocean and Atmosphere The fluxed of organic carbon must be sustained by an adeguate flux of macronutrients

  33. Phytoplankton Blooms Bands of the dionflagellate Lingulodinium polyedrum moving onshore over the troughs of a series of internal waves

  34. Trophic levels and dynamics Food Web Energy

  35. How about Cyanobacteria?

  36. Hydrothermal vents and Chemosynthetic bacteria

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