1. Eddy-driven changes in phytoplankton community composition and biogeochemical cycling in the Sargasso Sea NASA A regional eddy-resolving carbon cycle model surrounding the Bermuda Atlantic Time-Series Study (BATS) site: analysis of remotely sensed and in situ observations http://science.whoi.edu/users/mcgillic/tpd/anim.html NSF EDdy Dynamics, MIxing, Export, and Species composition http://science.whoi.edu/users/mcgillic/eddies/Eddies_Project.html VIMS

2. New Production in the Open Ocean

3. H 1 : Eddy-induced upwelling, in combination with diapycnal mixing in the upper ocean, introduces new nutrients into the euphotic zone. H 2 : The increase in inorganic nutrients stimulates a physiological response within the phytoplankton community. H 3 : Differing physiological responses of the various species bring about a shift in community structure. H 4 : Changes in community structure lead to increases in export from, and changes in biogeochemical cycling within, the upper ocean. Hypotheses

4. Three types of eddies in the Sargasso Sea Conceptual model: Cyclones and Mode-Water Eddies will cause plankton blooms as they form and intensify. Depth

5. Objectively Mapped Sea Level Anomaly Real time data feed: Bob Leben, CCAR http://www-ccar.colorado.edu/realtime/nwatlanticreal-time_ssh).

6. Cyclone C1 SLA and shipboard ADCP Temp. Sal. Fluor. O 2 Sat Hydro Section: 0-250m

7. C1 Phytoplankton Species Composition CHORS HPLC + Letelier et al. (1993)

8. Cyclone C1 oxygen profiles Outside Survey 1 Inside Survey 2 Inside Survey 1 Implied remineralization: 1-3 X ANP BATS Envelope

9. Target Feature A4 Sea Level Anomaly Cross Section

10. A4 Chl Peak vs. BATS 1988-2003 BATS: mean=.28; std=0.14; max=1.15 A4 Peak = 1.4 Shipboard cell counts: Chaetoceros spp. 8000 colonies l -1 15 cells per colony = ~10 5 cells l -1 Typical diatom conc: 1-10 cells l -1 A4 enhancement: 4-5 orders of magnitude above background CHORS HPLC: diatoms>60% total Chl a μg Chl a l -1 # Observations

11. MODIS Image of A4 August 6, 2005 Chlorophyll SST

12. A4 Productivity vs. BATS 1988-2003 Primary Production (mg C m -3 d -1 )

13. A4 Deep Oxygen Anomaly Implied remineralization = 1.6 X ANP BATS envelope

14. A Regional Hindcast Model Around BATS Valery Kosnyrev http://science.whoi.edu/users/mcgillic/tpd/tpd.html

15. BATS Retrospective Analysis 1993-1995 Blue: Cyclones Red: Anticyclones Pink: Mode-water Eddies BATS HPLC + Letelier et al. (1993) % total Chl Sweeney et al. (2003)

16. Why are Mode-water eddies so productive? 1.Enhanced mixing: trapping and amplification of near-inertial motions (Kunze, 1985) 2.Upwelling due to eddy-wind interactions (Martin and Richards, 2001)

17. Martin and Richards

18. Upwelling calculations for A4 QSCAT Ship Vertical velocity w ave =0.27 m d -1

19. CycloneMode-Water Eddy Upper therm. disp.Upward MacronutrientsEnhancement Eddy-wind int.DownwellingUpwelling MixingEnhanced Revisions to the conceptual model Diatoms Picoplankton

20. EDDIES data document extreme variability Chl a, 14 C Productivity, O 2 Cyclones and MWEs produce phytoplankton blooms MWEs: extraordinary (relative to BATS) sustained diatom biomass MWEs favor enhanced nutrient supply enhanced mixing upwelling (wind + heating) Export flux can be inferred from O 2 anomalies in the aphotic zone C1 signal: 1-3 x ANP: “The Smoking Gun” Conclusions

21. WHOI LANL Dennis McGillicuddy Mat Maltrud Larry Anderson Rick Smith Scott Doney A High Resolution Model of the North Atlantic Cyclones + MWEs; τ (u a,u o ); diatoms + picoplankton

22. End

23. ADCP Shear: C5, A4, C3 (OC415)

24. Cyclone C1 oxygen profiles Outside, Survey 1 Inside, Survey 2 Inside, Survey 1 Implied remineralization: 1-3 X ANP

25. A4 Productivity vs. BATS 1988-2003 BATS: blue dots 14 C Productivity Inside A4 Core PP (mg C m -3 d -1 ) Depth (m)

26. BATS Retrospective Analysis 1993-1995 Blue: Cyclones Red: Anticyclones Pink: Mode-water Eddies BATS HPLC + Letelier et al. (1993) % total Chl Sweeney et al. (2003)