1. Phytoplankton bloom – there is no officially recognized threshold level –range from 10,000s – 1,000,000s of cells per ml

2. Primary Production: Definitions and P vs. I Outline Review Light Beer’s Law Pigments Photoadaptation Photosynthesis Primary Productivity P vs. I Curves

4. More Aquatic Habitats (Vertical) Continental Shelf Continental Slope Abyss … Trench 1% Light Depth NeriticOceanic Coastal Euphotic zone Permanent Thermocline Bathypelagic mesopelagic EPIpelagic 25m 100m 1000m 200m Abyssopelagic Not shown: Seasonal Thermocline (varies, 10 – 400 m, depending on season and location)

6. What happens to absorbed light? Photosynthetically active radiation (PAR) 400 – 700 nm or visible light Absorbed PAR

7. Scattered back out into the atmosphere Can be detected by sensors in air or orbit

8. What happens to absorbed light? Photosynthetically active radiation (PAR) 400 – 700 nm or visible light Absorbed PAR Scattered back out into the atmosphere Can be detected by sensors in air or orbit Absorbed by water Heats it up

9. What happens to absorbed light? Photosynthetically active radiation (PAR) 400 – 700 nm or visible light Absorbed PAR Scattered back out into the atmosphere Can be detected by sensors in air or orbit Absorbed by water Heats it up Absorbed by plant pigments Photosynthesis

10. What happens to absorbed light? Photosynthetically active radiation (PAR) 400 – 700 nm or visible light Absorbed PAR Scattered back out into the atmosphere Can be detected by sensors in air or orbit Absorbed by water Heats it up Absorbed by plant pigments Photosynthesis Absorbed by dissolved materials Photochemistry

11. Attenuation = a decrease in the energy of light due to absorption and scattering in the water column Attenuation coefficient (K) = describes the exponential decay of light with depth within the water column

12. Irradiance in the Ocean I z = irradiance at depth z I 0 = irradiance at surface k = attenuation coefficient (m -1 ) (k also called absorption or extinction coefficient) I z = I 0 e -kz Beers Law I z

13. Phytoplankton Pigments Pigments Organic compounds (or organometals) that absorb light. Pigment – protein (complexes) Include chromophores (pigment molecules) bound covalently to protein structures.

14. Roles of Pigments Absorb light energy for photosynthesis (Light Harvesting) Intercept or dissipate harmful light energy (Photoprotection) Convert light energy into chemical energy (Photochemistry)

15. Classes of Pigments in Marine Plants Chlorophylls Carotenoids Biliproteins

16. Pigment analysis Fluorometer Shine blue light Fluoresces red Chromatography HPLC machine

17. Classes of Pigments in Marine Plants Chlorophylls - Porphoryn rings, magnesium in center (light harvesting and photochemistry) –Chl a –Chl b –Chl c

18. Classes of Pigments in Marine Plants Chlorophylls - Porphoryn rings, magnesium in center (light harvesting and photochemistry) –Chl a –Chl b –Chl c Carotenoids – carotenes simple chains of carbon and hydrogen (photoprotection) –Xanthophylls 400-500 nm gives brown color to marine plants –Beta-carotene does not feed energy in but absorbs light for plants (sunscreen) protects phototrap from receiving too many electrons –Fucoxanthin 510-525 nm give diatoms brown, olive-green color

19. Classes of Pigments in Marine Plants Chlorophylls - Porphoryn rings, magnesium in center (light harvesting and photochemistry) –Chl a –Chl b –Chl c Carotenoids – carotenes simple chains of carbon and hydrogen (photoprotection) –Xanthophylls 400-500 nm gives brown color to marine plants –Beta-carotene does not feed energy in but absorbs light for plants (sunscreen) protects phototrap from receiving too many electrons –Fucoxanthin 510-525 nm give diatoms brown, olive-green color Biliproteins water soluble accessory pigments (reds, blues, purples) (photosynthetic light harvesting only) –Phycoerythrin 500-570 nm, Phycocyanin 550-650 nm (red orange)

21. Absorption of light by Phytoplankton Pigments 400 500 600 700 Visible (PAR)

22. Absorption Spectra

23. Photoadaptation phytoplankton manufacture more chlorophyll –Increase umbrella to catch more of the sun's rays phytoplankton manufacture accessory pigments –expand the color range over which light can be captured phytoplankton manufacture a set of pigments called protective pigments (carotenoids) –prevent intense sunlight from damaging the photosynthetic apparatus, wide absorption bands that capture light energy and turn it into heat = photoinhibition

24. Antenna Complicated array of accessory pigments (carotenes, xanthophylls, phycobilins) Why do we care about pigments?

25. Some planktonic algae have large amounts of accessory pigments as well as Chl. What would the benefit be to that cost?

26. Biogeochemical Perspective on Biological Oceanography Rate Processes: Chemical transformations in the environment Primary productivity (Photosynthesis and Respiration) Remineralization Concept: Control of rate processes Concept: Limitation of rate processes

27. Primary Production (PP) The amount of autotrophic biomass produced per unit area (or vol) per unit time. PP  P – R PP rate is independent of biomass eaten by grazers, lost to sinking, etc. range from 1-5 g C/ m-2/ year-1 (central gyres) to 200-400 g C/ m-2/ year-1 (upwelling areas)

28. 1 m Biomass (B) - The amount of living matter per area or volume g C m -2, mg Chl a m -3 1 m

29. Photosynthesis 6CO 2 + 6H 2 O → C 6 H 12 O 6 + 6 O 2 LIGHT & pigments Respiration 6CO 2 + 6H 2 O ← C 6 H 12 O 6 + 6 O 2

30. Photosynthesis 6CO 2 + 6H 2 O → C 6 H 12 O 6 + 6 O 2 Respiration 6CO 2 + 6H 2 O ← C 6 H 12 O 6 + 6 O 2 Expressed as the RATE per VOLUME of the BIOMASS produced (mg C m-3 h-1) the BIOMASS-SPECIFIC rate: (mg C mg Chl a-1 h-1) <- Assimilation Number Photosynthesis can be expressed as: Amount of carbon fixed OR Amount of oxygen released

31. IMPORTANT NOTE: Photosynthesis is not equal to Primary Production Example: Organisms also do RESPIRATION (R) CH 2 O + O 2 → CO 2 + H 2 O + Energy

32. Gross Primary Productivity (P g ) –Total PP Net Primary Productivity (P n ) –Gross PP – plant respiration

33. Primary Productivity (PP) rate Respiration (R) rate Photosynthesis (P) rate = mass/area or volume/time mg O 2 /l/t

34. Estimating Primary Productivity In a bottle of known volume, incubate for a whole day. P and R → ← R 1) Measure the increase in oxygen over a given period of time 2) Measure the uptake of labeled carbon ( 14 C) by the phytoplankton. GROSS Primary Production Rate NET Primary Production Rate P g – R = P n

35. Measuring Primary Production (PP) photoinhibition

36. Photosynthesis Is a function of VISIBLE LIGHT Photosynthetically Available Radiation (PAR) Quantity of light that stimulates photosynthesis The relationship between Photosynthesis and Irradiance (PAR) is called the P-I CURVE

37. Photosynthesis – Irradiance Curve P is the photosynthesis rate (matter / volume*time) I is the irradiance, light intensity (cal cm -2 min -1 ) 1 cal cm -2 min -1 (PAR) =3.15x10 -4 μmol m -2 s -1 P Irradiance (I or E)

38. Photosynthesis – Irradiance Curve P max is the maximal rate of photosynthesis I k is the irradiance saturation parameter (varies for different plants)  is the initial slope of the P vs. I curve P Irradiance (I or E) P max  IkIk

39. Photosynthesis – Irradiance Curve I b is the irradiance at which photoinhibition occurs  is the decrease in P with increasing irradiance under photoinhibition. P Irradiance (I or E) PmPm  IkIk IbIb 

40. Photosynthesis – Irradiance Curve Changes in  reflect changes in the light harvesting capacity and efficiency of the light reactions of photosynthesis (cellular properties) Changes in P m reflect changes in the enzymatic capacity (e.g. the dark reactions of photosynthesis). P Irradiance (I or E) PmPm  IkIk IbIb 

41. Photosynthesis – Irradiance Curve Photoinhibition reflects damage (reversible or irreversible) to the photosynthetic system … can be caused by UV damage and excessive visible light flux, modulated by time of exposure. P Irradiance (I or E) PmPm  IkIk IbIb 