1. Biological Productivity in the Ocean
Part I

2. Overview
Productivity is related to photosynthesis, which is affected by sunlight and nutrients.
Productivity is globally and seasonally variable.
Feeding relationships are represented by food chains and food webs.
Oceans are being overfished.

3. Primary Productivity
Primary productivity = storage of energy in organic matter that comes from a non-organic source like the sun (not from other plants or animals)
Photosynthesis uses solar radiation.
Chemosynthesis uses chemical reactions.
99.9% of the ocean’s biomass relies directly or indirectly on photosynthesis for food.

4. Energy to Food: Photosynthesis

5. Cyanobacteria

6. Cyanobacteria
Diatoms

7. Cyanobacteria
Dinoflagellates
Diatoms

8. Seagrass
Dinoflagellates
Diatoms

9. Seagrass
Dinoflagellates
Kelp

10. Seagrass
Mangroves
Kelp

11. Photosynthesis vs. Respiration
Photosynthesis: Creates food & releases O2, daylight only
Respiration: Burns food, releases CO2, day and night

12. Measurement of Primary Productivity
Directly – capture plankton in plankton nets
Measure radioactive carbon in seawater
Monitor ocean color with satellites
Green pigment chlorophyll
SeaWiFS

13. Ocean Chlorophyll – SeaWiFS Satellite

14. Factors Affecting Primary Productivity
Nutrient availability
Nitrate, phosphorous, iron, silica
Most from river runoff
Productivity high along continental margins
Redfield ratio – C:N:P proportions usually 106:16:1 for most phytoplankton

15. Factors Affecting Primary Productivity
Solar radiation
Uppermost surface seawater and shallow seafloor
Compensation depth – net photosynthesis becomes zero (O2 produced = CO2 produced)
Euphotic zone—from surface to about meters (330 feet)

16. Light Transmission in Ocean Water
Blue wavelengths penetrate deepest
Longer wavelengths (red, orange) absorbed first

17. Transmission of Light in Seawater

19. Color in the Ocean
Color of ocean ranges from deep blue to yellow- green
Factors
Turbidity from runoff
Photosynthetic pigments (chlorophyll)
Eutrophic (high CHL)
Oligotrophic (low CHL)
Secchi Disk – measures water transparency

20. Upwelling and Nutrient Supply
Cooler, deeper seawater is nutrient-rich.
Areas of coastal upwelling are sites of high productivity.

21. Types of Photosynthetic Marine Organisms
Anthophyta
Seed-bearing plants
Macroscopic (large) algae
Microscopic (tiny) algae
Photosynthetic bacteria

22. Anthophyta Only in shallow coastal waters
Primarily grasses and mangroves
Eelgrass

23. Surfgrass

24. Young Mangroves

25. Young Lemon Shark in mangrove roots

26. Upside-down Jelly in
Mangrove roots

27. Anthophyta
Mangrove
seed pods

28. Mangrove Swamps in Florida Keys

29. Macroscopic Algae
“Seaweeds”
Brown algae
Green algae
Red algae

30. Macroscopic Algae
Southern Sea Palm
Elk Kelp

31. Giant Kelp

32. Giant Kelp Attach to rocks with holdfasts Unlike roots
• Do not absorb nutrients
• Do not take in water
• Sole function is to hold
plant in place

33. Giant Kelp & Urchin Predators

34. Microscopic Algae Produce food for 99% of marine animals
Most are planktonic (“free-floating”)
Diatoms – tests (shells) made of silica
Coccolithophores – plates of calcium carbonate
Dinoflagellates – tail-like flagella

35. Microscopic Algae Diatoms silica-shelled organisms
dominant in colder water
diatomaceous ooze

36. Microscopic Algae Coccolithophores carbonate-shelled organisms
dominant in warmer waters

37. Microscopic Algae Coccolithophores carbonate-shelled organisms
dominant in warmer waters

38. Microscopic Algae Dinoflagellates Two whip-like flagella
for propulsion

39. Microscopic Algae Dinoflagellates “Red tides” Toxic algal blooms
Phosphorescence
But most not harmful
Lingulodinium
polyedrum

40. Microscopic Algae Dinoflagellates Lingulodinium polyedrum,
San Diego County

41. Microscopic Algae Dinoflagellates Zooanthellae
photosynthesize inside corals
and provide nutrients:
Symbiotic relationship

42. Photosynthetic Bacteria
Cyanobacteria
Extremely small
May be responsible for half of total photosynthetic biomass in oceans
Very important: bring new nitrogen into marine ecosystems

43. Photosynthetic Bacteria