1. Marine Ecosystems and Food Webs

2. Carbon Cycle Marine Biota Export Production

3. Export Production of Organic Carbon

4. Trophic levels and dynamics Ocean Ecosystem Structure

5. Trophic levels and dynamics Ocean Ecosystem Structure

6. Trophic levels and dynamics Ocean Ecosystem Structure

7. Trophic levels and dynamics Ocean Ecosystem Structure

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

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

10. Trophic levels and dynamics Food Web Energy

11. ENERGY

13. How about Mass Transfer?

18. How do we measure Biomass? Mass transfers are more easy to keep track than energy transfers

19. Alaska

20. 200 km Large scale Eddies

22. Color sensor satellites: MODIS, SeaWiFS, MERIS, OCTS, and CZCS http://oceancolor.gsfc.nasa.gov/SeaWiFS

23. A simplified diagram of an ecosystem

24. 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

25. 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, 1934. This works stems from his participation as a physiologist in the voyages of WHOI's first research vessel Atlantis. Atlantis in 1934 and today

26. source 1) atmosphere source 1) not biological, not atmospheric 2) fluvial C : N : P source 1) from N2 atmosphere gas 2) ocean subsurface 3) remineralization of dead organic matter 4) biological (e.g. excretions) At large Nitrogen appears to be the limiting factor in ocean productivity in today ’ s oceans

27. What is the explanation for the Redfield ratio? Redfield (1958) “biological control of chemical factors" in the ocean: living organisms in the ocean evolved to have a N:P ratios of about 16 → when N is not limiting then N and P but also C and O interact to produce this relation. Very stable in deep ocean Not so stable between phytoplankton species. Perhaps only general average?

28. N D P Z h S(N o -N ) Simple Nitrogen Model N=nitrogen P=phytoplank. Z=zooplank. D=detritus ~1 Pg C (0.2 % of photosynthetic biomass) NPP Net Primary Production (NPP) ~45 Pg C/yr Phytoplankton biomass turns over in about a week!

29. NO 3 Chlorophyll Large detritus Organic matter N2N2 NH 4 NO 3 Water column Sediment Phytoplankton NH 4 Mineralization Uptake Nitrification Grazing Mortality Zooplankton Susp. particles Aerobic mineralization Denitrification N2N2 Fixation Mix Layer depth Description of the oceanic ecosystem based on Nitrogen exchanges

30. Carbon Cycle Marine Biota 45 GIC/yr Export Production

31. What are the controls on Primary Production?  Ocean Circulation (e.g. gyres, coastal upwelling, eddy fluxes) modulates the fluxes of essential nutrients  Ocean nutrient inventory  Utilization of nutrients in HNLC (High Nutrients Low Chlorophyll regions)  Changes in Redfield Ratio

32. Export Production of Organic Carbon

33.  Ocean Circulation (e.g. gyres, coastal upwelling, eddy fluxes) modulates the fluxes of essential nutrients  Ocean nutrient inventory  Utilization of nutrients in HNLC (High Nutrients Low Chlorophyll regions)  Changes in Redfield Ratio What are the controls on Primary Production?

34. Nutrient Sources for Primary Production The flux of organic carbon must be sustained by an adequate flux of macronutrients If macronutrients are unavailable then primary production is reduced! What are the controls on Primary Production?

35. Surface CHL-A 1) Central Gyres2) Upwelling Regions

36. Phytoplankton Blooms and Physical Environment Bands of the dionflagellate Lingulodinium polyedrum moving onshore over the troughs of a series of internal waves

37. Nonlinear Internal Waves and Phytoplankton Isopycnals

38.  Ocean Circulation (e.g. gyres, coastal upwelling, eddy fluxes) modulates the fluxes of essential nutrients  Ocean nutrient inventory  Utilization of nutrients in HNLC (High Nutrients Low Chlorophyll regions)  Changes in Redfield Ratio What are the controls on Primary Production?

39.  Ocean Circulation (e.g. gyres, coastal upwelling, eddy fluxes) modulates the fluxes of essential nutrients  Ocean nutrient inventory Nitrogen appears to be the limiting factor for growth in modern time. C : N : P 106 : 16 : 1 What are the controls on Primary Production?

40. N* = N – 16 P (Gruber & Sarmiento 1997) N = 25790 N 2 fixation Denitrification Modern TIME

41.  Ocean Circulation (e.g. gyres, coastal upwelling, eddy fluxes) modulates the fluxes of essential nutrients  Ocean nutrient inventory  Utilization of nutrients in HNLC (High Nutrients Low Chlorophyll regions)  Changes in Redfield Ratio What are the controls on Primary Production?

43. Southern Ocean HNLC Map of annual average nitrate concentrations in the surface waters of the oceans. Data from Levitus, World Ocean Atlas, 1994.

44.  Ocean Circulation (e.g. gyres, coastal upwelling, eddy fluxes) modulates the fluxes of essential nutrients  Ocean nutrient inventory  Utilization of nutrients in HNLC (High Nutrients Low Chlorophyll regions)  Changes in Redfield Ratio What are the controls on Primary Production?

45.  Ocean Circulation (e.g. gyres, coastal upwelling, eddy fluxes) modulates the fluxes of essential nutrients  Ocean nutrient inventory  Utilization of nutrients in HNLC (High Nutrients Low Chlorophyll regions)  Changes in Redfield Ratio What are the controls on Primary Production? Climate Variability and Change