1. …in the Ocean…
Biological Productivity

2. We know what the ocean zones are and who lives there…but HOW do they live there together?
TROPHIC STRUCTURE:
Flow of energy or matter through an ecosystem, a “feeding” or trophic system
Primary, Secondary etc. PRODUCERS AND CONSUMERS
Food web/chain/pyramid

3. Ecosystems function by the exchange of matter and energy.
An ecosystem is the totality of the environment encompassing all parts:
Chemical
Physical
Geological
Biological
Ecosystems function by the exchange of matter and energy.

4. Plants use chlorophyll in photosynthesis:
to convert inorganic material into organic compounds
to store energy for growth and reproduction
Plants are autotrophs and the primary producers in most ecosystems.

5. Herbivores eat plants and carnivores eat animals; omnivores eat both.
All other organisms are heterotrophs, the consumers and decomposers in ecosystems.
Herbivores eat plants and carnivores eat animals; omnivores eat both.
Material is constantly recycled in the ecosystem.
Energy gradually dissipates as heat and is lost.

6. Ecosystem Model

7. The word “trophic” refers to nutrition
Trophic dynamics is the study of the nutritional interconnections among organisms within an ecosystem.
Trophic level is the position of an organism within the trophic structure of an ecosystem.
Autotrophs form the first trophic level.
Herbivores are the second trophic level.
Carnivores occupy the third and higher trophic levels.
Decomposers form the terminal level.

9. A food chain is the succession of organisms within an ecosystem based upon trophic dynamics.
Who is eaten by whom.
Fnft: Simple Food Chain

10. A food web consists of interconnected and interdependent food chains
Fnft: Food Web

11. An energy pyramid represents a food chain in terms of the energy contained at each trophic level.
The size of each level in an energy pyramid is controlled by the size of the level immediately below.
Fnft: Energy Pyramid

12. Figure 12.8
A generalized trophic pyramid. How many kilograms of primary producers are necessary to maintain 1 kilogram of tuna, a top carnivore? What is required for an average tuna sandwich? Using the trophic pyramid model shown here, you can see that 1 kilogram of tuna at the fifth trophic level (the fifth feeding step of the pyramid) is supported by 10 kilograms of midsize fish at the fourth, which in turn is supported by 100 kilograms of small fish at the third, which have fed on 1,000 kilograms of zooplankton (primary consumers) at the second, which have eaten 10,000 kilograms of phytoplankton (small autotrophs, primary producers) at the first. The quarter-pound tuna sandwich has a long and energetic history. (These figures have been rounded off to illustrate the general principle. The actual measurements are difficult to make and quite variable.)

13. Food chains transfer energy from one trophic level to another
Biomass is the quantity of living matter per unit area or per volume of water.
With each higher trophic level:
the size of organisms generally increases
the reproductive rate decreases
The number of organisms decreases
the total biomass decreases

14. The two major food chains in the ocean are:
the grazing food chain
the detritus food chain (non-living wastes form the base of the food chain)
Only about 10-20% of energy is transferred between trophic levels.
This produces a rapid decline in biomass at each successive trophic level.

15. Energy Transfer Between Trophic Levels
Fnft: Energy Transfer Between Tropic Levels

16. As the primary producers, plants require for photosynthesis :
Sunlight
Nutrients
Water
Carbon dioxide
The formula for photosynthesis is:
6CO2 + 6H2O + solar energy  C6H12O6 (sugar) + 6 O2

17. Sun Light energy Producers To space Consumers Photosynthesizers:
Green plants
and algae, and specialized
bacteria
Figure 12.3
The flow of energy through living systems. At each step, energy is degraded (that is, transformed into a less useful form).
To space
Chemical energy (carbohydrates, etc.)
Consumers
Respirers:
Animals and decomposers and plants at night
Energy of movement, waste heat, entropy

18. Figure 12.5
(a) Oceanic productivity—the incorporation of carbon atoms into carbohydrates—is measured in grams of carbon bound into carbohydrates per square meter of ocean surface area per year (gC/m2/yr).

19. Figure 12.5
(b) The diatom Coscinodiscus, an important marine primary producer. This diatom is about the size of the period at the end of this sentence.

20. Sunlight and nutrients are the limiting factors in marine ecosystems.
Phytoplankton blooms are the rapid expansion of a phytoplankton population because sunlight and nutrients are abundant.

21. Factors that limit plant growth and reduce primary production include:
Major Factors:
solar radiation
nutrients
Secondary Factors:
Upwelling
Turbulence
grazing intensity
turbidity
Only 0.1 to 0.2% of solar radiation is used for photosynthesis, and its energy stored in organic compounds.

22. Primary production is the total amount of carbon (C) converted into organic material per square meter of sea surface per year
(gC/m2/yr)

23. In the tropics and subtropics sunlight is abundant.
Productivity varies greatly in different parts of the ocean in response to the availability of nutrients and sunlight.
In the tropics and subtropics sunlight is abundant.
This generates a strong thermocline that:
restricts upwelling of nutrients
results in lower productivity
High productivity locally occurs in:
areas of coastal upwelling
tropical waters between the gyres
coral reefs

24. In temperate regions productivity is distinctly seasonal.
Polar waters are nutrient-rich all year.
Productivity is only high in the summer when light is abundant.

25. Variations in Primary Productivity
North Atlantic
Tropics

26. Spring Diatom Bloom in the North Atlantic

27. It is highest in estuaries and lowest in the open ocean.
Primary productivity varies from 25 to 1250 gC/m2/yr in the marine environment.
It is highest in estuaries and lowest in the open ocean.
In the open ocean primary productivity distribution resembles a “bull’s eye” pattern.
The lowest productivity is in the center
The highest is at the edge of the basin
Water in the center of the ocean is a clear blue because it is an area of downwelling, above a strong thermocline.
It is almost devoid of biological activity.

28. Continental shelves display moderate productivity between 50 and 200 gC/m2/yr.
This is because:
nutrients wash in from the land
tide- and wave-generated turbulence recycle nutrients from the bottom water
Polar areas have high productivity because there is no pycnocline to inhibit mixing.
Equatorial waters have high productivity because of upwelling.
Centers of circulation gyres, which occupy most of the open ocean, are biological deserts.

29. Global Variations in Primary and Secondary Production
Fnft: Primary Productivity

30. Figure 12.6
Oceanic productivity can be observed from space. NASA’s SeaWiFS satellite, launched in 1997, can detect the amount of chlorophyll in ocean surface water. Chlorophyll content provides an estimate of productivity. Red, yellow, and green areas indicate high primary productivity; blue areas indicate low. This image was derived from measurements made between September 1997 and August 1998.

31. Figure 12.5
(c) Net annual primary productivity in some marine and terrestrial communities.

32. Upwelling in the South Pacific
Figure Upwelling

33. Coastal Upwelling

34. …so that’s only 1 side of the equation…

35. What about the CONSUMERS?

36. Animals must consume pre-existing organic material to survive
Animals break down the organic compounds into their inorganic components to obtain the stored energy.
The chemical formula for respiration is:
C6H12O6 (sugar) + 6O2  6CO2 + 6H2O + Energy

37. The recovered energy is used for:
Movement
Reproduction
Growth
The food consumed by most organisms is proportional to their body size (exceptions occur).
Smaller animals eat smaller food
Larger animals eat larger food

38. The basic feeding strategies of animals are:
Grazing
Predation
Scavenging
Filter feeding
Deposit feeding
Population size is dependent upon food supply and grazing pressure.

39. Feeding Strategies Predator Filter Feeder Scavenger Barracuda
Feather Duster Worms
Crab

40. Prey-Predator Relationships
Fnft: Prey-Predator Relationships

41. And finally, the “other” consumer…

42. Bacteria are decomposers.
They break down organic material and release nutrients for recycling.

43. Fnft: Nutrient Cycling

44. Now let’s break it down…
…the “basics”
Food Webs and Trophic structures are different in different parts of the world (i.e. each HABITAT has its’ own unique balanced feeding structure)
Each section is a (larger) part of the whole

45. Fnft: Simplified paths of the flow of oxygen and carbon in an idealized marine ecosystem

46. Fnft: Biogeochemical cycle of nitrogen or phosphorus

47. Fnft: Energy flow in a marine ecosystem

49. Fnft: Major biotic components of a marine ecosystem
Adapted from W. D. Russell-Hunter. Aquatic Productivity. Macmillan, 1970

50. Fnft: Food pyramid that leads to an adult herring

51. Figure 15.24
Herring during
different
stages of
development
(growth)

52. Figure 10.13
antarctic
food
chain

53. Figure 10.14
antarctic
food
web

54. Figure 12.9
A simplified food web, illustrating the major trophic relationships leading to an adult killer whale. The arrows show the direction of energy flow; the number on each arrow represents the trophic level at which the organism is feeding. Note that feeding relationships are not as simple as one might assume from Figure 12.8.

55. Figure 16-2 Benthic Food Web
Figure 16-2 Benthic Food Web. Detritus forms the basis of the benthic food web in coastal seas.
Benthic food web

56. Figure 15.25
Epipelagic
Food
web

57. Epipelagic food web

58. Remember
EACH habitat will have its own food web/trophic structure based on:
- location (and water chemistry)
- organismal make-up
- other abiotic “influences” (including proximity to land/pollution sources)
WATCH FOR THESE AS WE STUDY EACH HABITAT IN THE COURSE!