1. Chapter 13 Biological Productivity and Energy Transfer
Essentials of Oceanography
7th Edition

2. Primary productivity
Primary productivity is the amount of carbon (organic matter) produced by organisms
Mostly through photosynthesis
Energy source = solar radiation
Also includes chemosynthesis
Energy source = chemical reactions

3. Photosynthetic productivity
Figure 13-1

4. Oceanic photosynthetic productivity
Controlling factors affecting photosynthetic productivity:
Availability of nutrients
Nitrates
Phosphates
Iron
Amount of sunlight
Varies daily and seasonally
Sunlight strong enough to support photosynthesis occurs only to a depth of 100 meters (euphotic zone)

5. Locations of maximum photosynthetic productivity
Margins of the oceans
Abundant supply of nutrients from land
Water shallow enough for light to penetrate all the way to the sea floor
Upwelling areas
Currents hoist cool, nutrient-rich deep water to the sunlit surface

6. Coastal upwelling
Figure 13-3

7. The electromagnetic spectrum and light penetration in seawater
Figure 13-4

8. Water color and life in the ocean
Ocean color is influenced by:
The amount of turbidity from runoff
The amount of photosynthetic pigment, which corresponds to the amount of productivity
Yellow-green = highly productive water
Found in coastal and upwelling areas (eutrophic)
Clear indigo blue = low productivity water
Found in the tropics and open ocean (oligotrophic)

9. Satellite view of world productivity
Figure 13-6

10. Photosynthetic marine organisms: Plants
Seed-bearing plants
Eelgrass (Zostera)
Surf grass (Phyllospadix)
Surf grass
Figure 13-7

11. Photosynthetic marine organisms: Macroscopic algae
Brown algae
Sargassum (top left)
Macrocystis (top right)
Green algae
Codium (bottom left)
Red algae
Lithothamnion (bottom right)
Figure 13-8

12. Photosynthetic marine organisms: Microscopic algae
Microscopic algae include:
Golden algae
Diatoms (silica test resembles a pillbox)
Coccolithophores (calcite plates form a spherical test)
Dinoflagellates
Produce a test made of keratin
Posses a whip-like flagella
Bioluminescence
Exist in great abundance, creating red tides (harmful algae blooms)

13. Dinoflagellates and red tides
Figure 13C

14. Regional productivity
Photosynthetic productivity varies due to:
Amount of sunlight
Availability of nutrients
Thermocline (a layer of rapidly changing temperature) limits nutrient supply
Examine three open ocean regions:
Polar oceans (>60° latitude)
Tropical oceans (<30° latitude)
Temperate oceans (30-60° latitude)

15. Productivity in polar oceans
Sunlight peaks in summer
Nutrients available nearly year-round (only weak seasonal thermocline develops)
Productivity:
Peaks in spring
Limited by sunlight
Figure 13-10a

16. Productivity in tropical oceans
Sunlight strong year-round
Nutrients limited by strong, permanent thermocline
Productivity:
Steady, low rate
Limited by nutrients
Exceptions:
Upwelling areas
Coral reefs
Figure 13-11

17. Productivity in temperate oceans
Sunlight varies seasonally
Nutrients limited by thermocline
Productivity:
Spring bloom limited by nutrients
Fall bloom limited by sunlight
Figure 13-12

18. Productivity in tropical, temperate, and polar oceans
Figure 13-13

19. Energy flow in marine ecosystems
Categories of organisms:
Producers
Consumers
Decomposers
Figure 13-14

20. Biogeochemical cycling of matter
Figure 13-16

21. Ecosystem energy flow and efficiency
Energy is passed between trophic (feeding) levels
Transfer efficiencies:
Algae = 2%
Other levels = 10%
Figure 13-18

22. Comparison between a food chain and a food web
Figure 13-19

23. Biomass pyramid At each step up the pyramid, there is/are:
Larger organisms
Fewer individuals
A smaller total biomass
Figure 13-20

24. Ecosystems and fisheries
Fishery = fish caught from the ocean by commercial fishers
Largest proportion of marine fish are taken from shallow shelf and coastal waters
Figure 13-21

25. Fisheries and overfishing
World total marine fish production has increased dramatically
Overfishing occurs when adult fish are harvested faster than their natural rate of reproduction
Figure 13-22

26. Fisheries and bycatch
Some fishing practices produce large amounts of incidental catch (bycatch):
Purse seine nets set for tuna can trap dolphins
Driftnets (gill nets) take many unwanted species
Spotted dolphin
Figure 13-23

27. Fisheries management
Fisheries management seeks to maintain a long-term fishery by:
Assessing ecosystem health
Determining fish stocks
Analyzing fishing practices
Enforcing catch limits
Fisheries management does not regulate the number of fishing vessels
Figure 13-25

28. Essentials of Oceanography 7th Edition
End of Chapter 13
Essentials of Oceanography
7th Edition