1. Coastal Upwelling Equatorward winds along a coastline lead to offshore Ekman transport Mass conservation requires these waters replaced by cold, denser waters Brings nutrients to the surface increasing rates of primary production Creates dynamic height gradients - currents

2. Coastal Upwelling

3. CalCoFI Cruise 9804

4. Coastal Upwelling Changes Density Line 90

5. Density & Currents for Line 90 Negative currents to south

6. Primary Production Phytoplankton h CO 2 O2O2 PlantsNUTS Light, carbon & nutrients make plants & O 2

7. Respiration & Remineralization remineralizers h CO 2 O2O2 PlantsNUTS Biological processes consume plants & O 2 to make CO 2 & nutrients

8. Euphotic Zone Euphotic Zone – PP happens Aphotic Zone - Respiration & Remineralization Depth of Euphotic Zone is f(water clarity) 100% Light1% Light

9. Euphotic Zone Defined as the depth where the light = 1% of the surface value A function of plant biomass or chlorophyll concentration Varies from 10 to 130 m Typically, Z eu = 3 * Secchi depth

10. CalCoFI Light Profiles % surface light Depth (m) Secchi = 7 m Secchi = 18 m

11. Primary Production Phytoplankton h CO 2 O2O2 PlantsNUTS Light, carbon & nutrients make plants & O 2

12. Facts & Predictions CO 2 will not be limiting In euphotic zone … – NUTS will be consumed – O 2 & plants will grow (high chlorophyll) In aphotic zone … – Remineralization produces CO 2 & NUTS – Consumes O 2 & plants

13. Facts & Predictions KEY: Upper layer biology is controlled by supply of nutrients to euphotic zone Upwelling is dominate process regulating primary production

14. Density & Currents for Line 90 Negative currents to south

15. NUTS for Line 90

17. Line 90 Results In euphotic zone … – NUTS are low – O 2 & plants are high (O 2 is supersaturated) In aphotic zone … – NUTS are high – O 2 & plants are low Pattern follows physical inflow

18. CalCoFI Cruise 9804

19. Link to Physical Process April 1978 AVHRR - SST CZCS Chlorophyll SST Chl

20. Coastal Upwelling

22. The Upwelling Conveyor Belt Highest NUTS & CO 2 High NUTSLow NUTS High ChlLow ChlLower Chl Sinking Flux of Carbon

23. Biological Water Masses Residence time in euphotic zone controls nutrient concentrations Source characteristics are also important

25. Primary Production Simple light-NUT model explains basic features regulating primary production Physical processes drive nutrient supply to euphotic zone & primary production Concept of “upwelling conveyor belt” Water mass characteristics