1. 3
Ecosystems and Energy

2. Overview of Chapter 3 What is Ecology? The Energy of Life
Laws of Thermodynamics
Photosynthesis and Cellular Respiration
Flow of Energy Through Ecosystems
Producers, Consumers and Decomposers
Path of Energy Flow: Who Eats Whom
Ecological Pyramids
Ecosystem Productivity

3. Chesapeake Bay salt marshes
An estuary – semi-enclosed body of water where freshwater drains into ocean
Tidal – gradual changed from fresh to salt water
Cordgrass dominates – brackish
Home to insects and birds, nursery for fish
Very important buffer for coasts against storms

4. Ecology Ecology Biotic - living environment
“logy” study of, “eco” house – study of one’s house
The study of interactions among and between organisms in their abiotic environment
Biotic - living environment
Includes all organisms
Abiotic - non living or physical environment
Includes living space, sunlight, soil, precipitation, etc.

5. Ecology
Organisms interact with biotic components, but also effect many physical and chemical processes
Physical – walking on soil
Chemical – CO2, O2, wastes

6. Ecology
Ecologists are interested in the levels of life above that of organism

7. Ecology Definitions
Species - A group of similar organisms whose members freely interbreed to produce fertile offspring
Population - A group of organisms of the same species that live in the same area at the same time
Community - All the populations of different species that live and interact in the same area at the same time
Ecosystem - A community and its physical (abiotic) environment
Landscape - Several interacting ecosystems (ex: bear hunting for salmon in a river, living in adjacent forest)

8. Ecology Part of Earth that contains living organisms
Community and physical environment
All populations of species in an area
Group of same species
Individuals

9. Ecology
Coral Reef communities – similar to rainforests for number of species and productivity
Threatened with changing climate
How can communities be protected from warming waters?
What could loss mean?

10. Ecology
Biosphere contains earth’s communities, ecosystems and landscapes, and includes:
Atmosphere- gaseous envelope surrounding earth
Hydrosphere- earth’s supply of water
Lithosphere- soil and rock of the earth’s crust

11. Ecology
Atmosphere
Lithosphere
Hydrosphere

12. Energy of Life The ability or capacity to do work
Chemical, Thermal, Mechanical, Nuclear, Electrical, and Radiant/Solar (below)

13. Energy of Life
Solar radiation is the primary source of energy on planet
Plants turn solar radiation into food

14. Energy of Life Energy exists as:
Potential energy (stored energy)
Kinetic energy (energy of motion)
Potential energy is converted to kinetic energy as arrow is released from bow

15. Thermodynamics Study of energy and its transformations
System- the object being studied
Closed System- Does not exchange energy with surroundings (rare in nature)
Open System- exchanges energy with surroundings

16. Laws of Thermodynamics
First Law of Thermodynamics
Energy cannot be created or destroyed; it can change from one form to another
Energy is absorbed by water and plate, but not lost

17. Laws of Thermodynamics
Second Law of Thermodynamics
When energy is converted form one form to another, some of it is degraded to heat
Heat is highly entropic (disorganized)
Water in sunlight will get warmer
Engine converts chemical energy of gasoline into mechanical energy inefficiently

18. Photosynthesis 6 CO2 + 12 H2O + radiant energy C6H12O6 + 6 H2O + 6 O2
Biological process by which energy from the sun (radiant energy) is transformed into chemical energy of carbohydrate (sugar) molecules
6 CO H2O + radiant energy
Chlorophyll in plants
C6H12O6 + 6 H2O + 6 O2

19. Cellular Respiration C6H12O6 + 6 O2 + 6 H2O 6 CO2 + 12 H2O + energy
The process where the chemical energy captured in photosynthesis is released within cells of plants and animals
This energy is then used for biological work
C6H12O6 + 6 O2 + 6 H2O
6 CO H2O + energy

20. Photosynthesis and Cellular Respiration

21. Life without Sun
1970s – discovered hydrothermal vents in deep ocean (200oC or 392oF)
Rich ecosystem supported without light
Bacteria perform chemosynthesis
Similar to photosynthesis, but use chemical (H2S) not sunlight

22. Energy Flow Through Ecosystems
Passage of energy through an ecosystem

23. Food Chains- The Path of Energy Flow
Energy from food passes from one organism to another based on their Trophic Level
Definition: An organism’s position in a food chain, which is determined by its feeding relationships
First Trophic Level: Producers
Second Trophic Level: Primary Consumers
Third Trophic Level: Secondary Consumers
Decomposers are present at all trophic levels

24. Food chains Autotrophs = Producers
Auto “self” and tropho “nourishment”
Produce own food from inorganic material
Ex: plants via photosynthesis and hydrothermal vent bacteria via chemosynthesis

25. Food chains Heterotrophs = Consumers
heter “different” and tropho “nourishment”
Uses bodies of other organisms as food
Omnivores – eat both plants and animals

26. Food chains Consumers of detritus (detritivores)
Eat dead material such as leaves, carcasses, feces
Ex: crabs, worms, millipedes, snails

27. Food chains Decomposers or saprotrophs
sapro “rotten” and tropho “nourishment”
Breakdown dead organic material
Release inorganic molecules (CO2 and nutrients) that producers can use
Ex: fungus, bacteria
Involved in all aspects of food chains

28. Food Web Food web visualizes feeding relationships within a community
More complex than food chain
Still simplified compared to nature

29. Humans and Antarctic food web
Base of web is algae, which is eaten by krill
Krill are eaten by many larger organisms
Wastes of whales resupply nutrients for algae and krill
Ozone and climate change are warming area

30. Ecological Pyramids
Graphically represent the relative energy value of each trophic level
Important feature - large amount of energy is lost as heat between trophic levels
Three main types
Pyramid of numbers
Pyramid of biomass
Pyramid of energy

31. Pyramid of Numbers
Illustrates the number of organisms at each trophic level
Fewer organisms occupy each successive level
Does not indicate:
biomass of organisms at each level
amount of energy transferred between levels

32. Pyramid of Biomass
Illustrates the total biomass at each successive trophic level
Biomass: measure of the total amount of living material
~90% reduction in biomass through trophic levels
100 to 10

33. Pyramid of Energy
Illustrates how much energy is present at each trophic level and how much is transferred to the next level
Most energy dissipates between trophic levels
Lost as heat and energy to maintain each level
Explains why there are so few trophic levels

34. Ecosystem Productivity
Gross Primary Productivity (GPP)
Total amount of energy that plants capture and assimilate in a given period of time
Cellular respiration (R)
Plants use some energy of GPP to maintain themselves
Plants respire too
Net Primary Productivity (NPP)
Productivity after respiration losses are subtracted
What is available as food for other organisms

35. Ecosystem Productivity
GPP is similar to gross pay in paycheck
R is similar to taxes
NPP is similar to take home pay
Net Primary Productivity (plant growth per area per time)
Gross Primary Productivity (total photosynthesis per area per time)
Plant Cellular Respiration
(per area per time) = -

36. Variation in NPP by Ecosystem
Coral reefs are near tropical rain forests
Humans consume a large amount of global NPP
~30% but we make up ~0.5% of biomass
This represents a threat to planet’s ability to support both human and non-human inhabitants

37. Energy and Climate Change
Humans use a large portion of global NPP
If we use more biomass as energy rather than fossil fuels, our use of NPP may increase
Corn as fuel, wood for heat
How can we balance our needs with other organisms?

38. ENVIRONEWS
Use of satellite imagery improves biomass estimates of forests
Help protect tropic forests in developing countries
Developed countries pay to keep forests intact
Need to ground truth satellite models with monitoring data from forest