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Ocean Productivity: A Personal Perspective

Ocean Productivity: A Personal Perspective. John Marra Brooklyn College, City University of New York. I missed the 1 st Liege Colloquium (1969). What’s happened over the last 44 years?. And now I live in Brooklyn…. A Review. 1990s. 1980s. Biogeochemistry (JGOFS) Ocean Color!

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Ocean Productivity: A Personal Perspective

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  1. Ocean Productivity: A Personal Perspective John Marra Brooklyn College, City University of New York 45th Liege Colloquium

  2. I missed the 1st Liege Colloquium (1969) What’s happened over the last 44 years? 45th Liege Colloquium

  3. And now I live in Brooklyn… 45th Liege Colloquium

  4. A Review 1990s 1980s • Biogeochemistry (JGOFS) • Ocean Color! • Picoplankton • Iron hypothesis • Method issues? • Emergence of bio-optics • Microbial loop 1970s 2000s • Eppley’s Temp. vs Growth • Nutrient kinetics • ‘Patchiness’ • Information theory • Global scales • -omics • Pumps: biological and microbial 45th Liege Colloquium

  5. Plankton Rate Processes in Oligotrophic OceanS (PRPOOS) Spring, 1983 45th Liege Colloquium

  6. But through it all, there has been one theme, one goal: “…determination of time-varying plankton productivity in the world ocean…” -Barber and Hilting (2002) (emphasis mine) 45th Liege Colloquium

  7. 14Carbon 14CO2 + H2O -> 14CH2O + O2 • Basis of virtually all satellite algorithms for productivity • Incubation from dawn-dusk very close to Net Primary Production • Characteristics invite methodological abuse and carelessness • Easy • Extremely Sensitive • Always gives a ‘positive’ answer 45th Liege Colloquium

  8. What We Don’t Know: Lingering Problems • The depth of theEuphotic Zone, or Productive Layer • Respiration and its components • Production and dynamics of dissolved organic matter (DOM) • How do we determine primary production in dynamic water columns 45th Liege Colloquium

  9. AUTOTROPHIC BACTERIAL, HETEROTROPHIC RESPIRATION DISSOLVED ORGANIC MATTER EUPHOTIC DEPTH 45th Liege Colloquium

  10. The Productive Layer of the Ocean Horizontal extent of is OK Vertical extent is unknown 45th Liege Colloquium

  11. The Compensation Depth (where P=R) defines the Euphotic Zone… …but it is never measured. 45th Liege Colloquium

  12. Compensation Depth and the Critical Depth 45th Liege Colloquium

  13. Y Models for Water Column Productivityand the Compensation Depth Y = aB/4.6 Falkowski, 1981 Platt, 1986 Requires an accurate definition of the euphotic zone (or productive layer)! 45th Liege Colloquium

  14. Phytoplankton Respirationfrom 14C Assimilation • If 14C uptake measures net primary production (dawn to dusk); • If 14C is at intracellular isotopic equilibrium by the end of the day; and • If daytime R = nighttime R, Then, Phytoplankton R = fx the Dark Loss of C (where f is a multiplier based on day:night hours, typically, 2 for 12:12) Marra and Barber, 2004, GRL 31, L09314 45th Liege Colloquium

  15. Summary of14C-based Rp Estimates • Grazing effects? • Diel changes in release of DOC? • Observational error? • R in the light? • Day-night differences in R? • Mehler reaction? Marra, 2009, AME 45th Liege Colloquium

  16. The Compensation Depth (where P=R) ONDEQUE program, NW Atlantic, 2008 Marra et al., submitted 1%Eo • P=R is at a depth that • Encompasses auto. Biomass, • Equals 1% Ed(490) • (satellite connection?) P=R 45th Liege Colloquium

  17. …but in the North Pacific… Ed(z) = Ed(0)e(-Kdz) The compensation depth is probably determined by biology, not light depth 45th Liege Colloquium

  18. AUTOTROPHIC BACTERIAL, HETEROTROPHIC RESPIRATION DISSOLVED ORGANIC MATTER EUPHOTIC DEPTH 45th Liege Colloquium

  19. CO2 CO2 Communication? Source Fate Phytoplankton Primary Production Bacterial Remineralization Bacterial remineralization inorganic compounds extracellular release, grazing, lysis, solubilization bioavailability DOM Lateral transport Export to deeper waters & sediments through aggregate and particulate sinking Advection • Estimated that 50% of primary production routed through dissolved fraction • DOM production cannot be captured by satellite sensors • Utilization of labile DOC will be as rapid as photosynthetic production • Not typically measured in productivity experiments • O2 evolution/CO2 consumption will include it, • 14C uptake may not • Won’t be measured in particle production methods 45th Liege Colloquium

  20. AUTOTROPHIC BACTERIAL, HETEROTROPHIC RESPIRATION DISSOLVED ORGANIC MATTER EUPHOTIC DEPTH …in a dynamic water column 45th Liege Colloquium

  21. The view of the seasonal re-stratification from a mooring at 60N/20W in the North Atlantic (south of Iceland) Plueddemann et al., 1995, JGR 45th Liege Colloquium

  22. Changes in thermal structure & phytoplankton from shipboard Diatoms .2-.3 mg Chl l-1 Phaeocystis 3-4 mg Chl l-1 45th Liege Colloquium

  23. The kind of ‘container’ Physically very dynamic in situ volume Very non-dynamic volume 45th Liege Colloquium

  24. Primary Production in the Ocean: From the Synoptic to the Global Scale AUTOTROPHIC BACTERIAL, HETEROTROPHIC RESPIRATION DISSOLVED ORGANIC MATTER EUPHOTIC DEPTH 45th Liege Colloquium

  25. You can´t knowwithout the Love Production Loss Respiration 45th Liege Colloquium

  26. Remembering Two Greats 1927-2012 1933-2012 45th Liege Colloquium

  27. Merci! 45th Liege Colloquium

  28. Extras 45th Liege Colloquium

  29. ONDEQUE, PP and Rpfor stations in the NW Atlantic 45th Liege Colloquium

  30. Productivity has known limits 1. Growth rate as a function of temperature (Eppley,1972) 2. The maximum rate of photo-synthesis normalized to chlorophyll-a and per hour, Pbmax, will be ≤ 25 3. The quantum yield. 8 quanta of light are required to evolve 1 mol O2, thus, the quantum yield will be < 0.1 (in practice) (Falkowski, 1981) (e.g., Bannister and Weidemann, 1983) 45th Liege Colloquium

  31. 45th Liege Colloquium

  32. Global Ocean Productivity Through the ‘Ages’ 45th Liege Colloquium

  33. Biomass: Changes in POC • Good for estimating particle production • Doesn’t measure DOC production • There are many more optically-based measurements of production in development 45th Liege Colloquium

  34. Carbon CO2+ H2O -> CH2O + O2 • It’s carbon! (no worries about value of the the photosynthetic quotient), but… • Precision is too low for most open ocean work 45th Liege Colloquium

  35. modeling: • Northern Gulf of Mexico 45th Liege Colloquium

  36. “…the results of the 14C method fall somewhere between the net phytoplankton production and total photosynthesis, but exact evaluation of the meaning of the experiments will require an extensive experimental programme” G. A. Riley (ca. 1954) 45th Liege Colloquium

  37. Primary Productivity “Let me count the ways…” 45th Liege Colloquium

  38. Comparing Fluxes: In Situ and in Containers 45th Liege Colloquium

  39. The JGOFS North Atlantic Bloom Experiment, Spring 1989 Over 13 days (mixed layer): • Production = 970 mmols C m-2 • Total increase in POC = 520 mmols C m-2 • Trap flux = 507 mmols C m-2 • (234Th estimates are about half the trap flux.) m 45th Liege Colloquium

  40. Synthesis of Energy from Light 45th Liege Colloquium

  41. Productivity Measurements • Two choices: • Fluxes from in situ dynamics • Fluxes occurring in bottles • Each has advantages and disadvantages 45th Liege Colloquium

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