1. 13-17 May 201345th Liege Colloquium 1 Ocean Productivity: A Personal Perspective John Marra Brooklyn College, City University of New York

2. I missed the 1 st Liege Colloquium (1969) 13-17 May 201345th Liege Colloquium 2 What’s happened over the last 44 years?

3. And now I live in Brooklyn… 13-17 May 201345th Liege Colloquium 3

4. A Review 13-17 May 201345th Liege Colloquium 4 1970s Eppley’s Temp. vs Growth Nutrient kinetics ‘Patchiness’ Information theory 1980s Method issues? Emergence of bio-optics Microbial loop 1990s Biogeochemistry (JGOFS) Ocean Color! Picoplankton Iron hypothesis 2000s Global scales -omics Pumps: biological and microbial

5. Plankton Rate Processes in Oligotrophic OceanS (PRPOOS) 13-17 May 201345th Liege Colloquium 5 Spring, 1983

6. But through it all, there has been one theme, one goal: 13-17 May 201345th Liege Colloquium 6 “…determination of time-varying plankton productivity in the world ocean…” -Barber and Hilting (2002) (emphasis mine)

7. 13-17 May 201345th Liege Colloquium 7 14 Carbon 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 14 CO 2 + H 2 O -> 14 CH 2 O + O 2

8. 13-17 May 201345th Liege Colloquium 8 What We Don’t Know: Lingering Problems The depth of the Euphotic 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

9. 13-17 May 201345th Liege Colloquium 9 AUTOTROPHICBACTERIAL, HETEROTROPHIC RESPIRATION DISSOLVED ORGANIC MATTER EUPHOTIC DEPTH

10. 13-17 May 201345th Liege Colloquium 10 The Productive Layer of the Ocean Horizontal extent of is OK Vertical extent is unknown

11. 13-17 May 201345th Liege Colloquium 11 The Compensation Depth (where P=R) defines the Euphotic Zone… …but it is never measured.

12. 13-17 May 201345th Liege Colloquium 12 Compensation Depth and the Critical Depth

13.  Models for Water Column Productivity and the Compensation Depth 13-17 May 201345th Liege Colloquium 13 Falkowski, 1981  =  B /4.6 Requires an accurate definition of the euphotic zone (or productive layer)! Platt, 1986

14. 13-17 May 201345th Liege Colloquium Phytoplankton Respiration from 14 C Assimilation If 14 C uptake measures net primary production (dawn to dusk); If 14 C is at intracellular isotopic equilibrium by the end of the day; and If daytime R = nighttime R, Then, Phytoplankton R = f x the Dark Loss of C (where f is a multiplier based on day:night hours, typically, 2 for 12:12) 14 Marra and Barber, 2004, GRL 31, L09314

15. 13-17 May 201345th Liege Colloquium Summary of 14 C-based Rp Estimates Grazing effects? Diel changes in release of DOC? Observational error? R in the light? Day-night differences in R? Mehler reaction? 15 Marra, 2009, AME

16. The Compensation Depth (where P=R) 13-17 May 201345th Liege Colloquium 16 ONDEQUE program, NW Atlantic, 2008 Marra et al., submitted 1%Eo P=R P=R is at a depth that Encompasses auto. Biomass, Equals 1% Ed(490) (satellite connection?)

17. …but in the North Pacific… 13-17 May 201345th Liege Colloquium 17 Ed(z) = Ed(0)e (-Kdz) The compensation depth is probably determined by biology, not light depth

18. 13-17 May 201345th Liege Colloquium 18 AUTOTROPHICBACTERIAL, HETEROTROPHIC RESPIRATION DISSOLVED ORGANIC MATTER EUPHOTIC DEPTH

19. 13-17 May 201345th Liege Colloquium 19 Phytoplankton Primary Production DOM CO 2 Bacterial remineralization extracellular release, grazing, lysis, solubilization inorganic compounds CO 2 Bacterial Remineralization Advection Lateral transport bioavailability 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 –O 2 evolution/CO 2 consumption will include it, – 14 C uptake may not –Won’t be measured in particle production methods Export to deeper waters & sediments through aggregate and particulate sinking Source Fate Communication?

20. 13-17 May 201345th Liege Colloquium 20 AUTOTROPHICBACTERIAL, HETEROTROPHIC RESPIRATION DISSOLVED ORGANIC MATTER EUPHOTIC DEPTH …in a dynamic water column

21. 13-17 May 201345th Liege Colloquium Plueddemann et al., 1995, JGR The view of the seasonal re-stratification from a mooring at 60N/20W in the North Atlantic (south of Iceland) 21

22. 13-17 May 201345th Liege Colloquium Changes in thermal structure & phytoplankton from shipboard Phaeocystis 3-4 mg Chl l -1 Diatoms.2-.3 mg Chl l -1 22

23. 13-17 May 201345th Liege Colloquium 23 The kind of ‘container’ Physically very dynamic in situ volumeVery non-dynamic volume

24. 13-17 May 201345th Liege Colloquium 24 AUTOTROPHICBACTERIAL, HETEROTROPHIC RESPIRATION DISSOLVED ORGANIC MATTER EUPHOTIC DEPTH Primary Production in the Ocean: From the Synoptic to the Global Scale

25. You can´t know without the Production Love Respiration Loss 13-17 May 2013 25 45th Liege Colloquium

26. Remembering Two Greats 13-17 May 201345th Liege Colloquium 26 1933-20121927-2012

27. Merci! 13-17 May 201345th Liege Colloquium 27

28. Extras 13-17 May 201345th Liege Colloquium 28

29. ONDEQUE, PP and R p for stations in the NW Atlantic 13-17 May 201345th Liege Colloquium 29

30. 13-17 May 201345th 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, P b max, will be ≤ 25 (Falkowski, 1981) 3. The quantum yield. 8 quanta of light are required to evolve 1 mol O 2, thus, the quantum yield will be < 0.1 (in practice) (e.g., Bannister and Weidemann, 1983)

31. 13-17 May 201345th Liege Colloquium 31

32. 13-17 May 201345th Liege Colloquium 32 Global Ocean Productivity Through the ‘Ages’

33. 13-17 May 201345th 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

34. 13-17 May 201345th Liege Colloquium 34 Carbon CO 2 + H 2 O -> CH 2 O + O 2 It’s carbon! (no worries about value of the the photosynthetic quotient), but… Precision is too low for most open ocean work

35. 13-17 May 201345th Liege Colloquium 35  modeling: Northern Gulf of Mexico

36. 13-17 May 201345th Liege Colloquium 36 “…the results of the 14 C 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)

37. Primary Productivity “Let me count the ways…” 13-17 May 201345th Liege Colloquium 37

38. 13-17 May 201345th Liege Colloquium 38 Comparing Fluxes: In Situ and in Containers

39. 13-17 May 201345th 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 (234 Th estimates are about half the trap flux.) m

40. 13-17 May 201345th Liege Colloquium 40 Synthesis of Energy from Light

41. 13-17 May 201345th Liege Colloquium 41 Productivity Measurements Two choices: –Fluxes from in situ dynamics –Fluxes occurring in bottles Each has advantages and disadvantages