1. Ecosystems 5.1

2. Vocabulary 5.1.1
Ecology – the study of relationships between organisms and between organisms and their environment

3. Vocabulary 5.1.1
Species: organisms that can interbreed in the wild and produce viable offspring – share a gene pool Two species can mate and not produce fertile offspring – instead called interspecies hybridization Example: female horse and male donkey produce mules

4. Vocabulary 5.1.1
Habitat – environment in which an organism normally lives Includes abiotic factors Must provide food, shelter, water and space to live Examples: fast moving stream, temperate forest

5. Vocabulary 5.1.1
Niche – the role an organism occupies in its environment What its job is in the ecosystem? Predator of mule deer etc. What tolerance limits does it have? temperature, pH, light intensity Two organisms cannot occupy the same niche at the same time – competitive exclusion principle

6. Vocabulary 5.1.1
Population – all members of a single species living in a given area at a given time. All the mice in Palmer High School this year.

7. Vocabulary 5.1.1
Community – ALL of the populations of different species living and interacting in a given area at a given time All the humans, mice, spiders, cockroaches living in Palmer High School this year.

8. Vocabulary 5.1.1
Ecosystem – a community interacting with its abiotic environment All the humans, mice, spiders, cockroaches living in Palmer High School this year with the heat, lights, water fountains, bathrooms, cafeteria, desks and lab equipment.

9. Environment Everything surrounding an organism Hydrosphere Atmosphere
Lithosphere
Biosphere

10. Troph = greek for nourishment
Nutrition = how an organism obtains
energy and
a carbon source to build the organic molecules of cells

11. Vocabulary 5.1.2
Autotroph – synthesizes its organic molecules from simple inorganic substances Photoautotroph – light a source of energy for synthesis in most communities Explants, protists, prokaryotes

12. Chemoautotroph 5.1.2 Use inorganic molecules as source of energy
usually hydrogen sulfide, amonia or iron compounds
prokaryotes found at
hydrothermal vents
(black smokers)
Nitrogen fixing soil
bacteria

13. Heterotroph 5.1.2
Organisms that obtain organic molecules from other organisms Ingest organisms to digest, ingest organic matter to digest, or digest outside and then absorb

14. Consumer 5.1.3
Ingest organisms that are living or recently killed and digest them internally

15. Detritivores 5.1.3 Ingests non-living organic matter
Dead plant and animal material
Fill the decomposer niche
Earthworms, crabs

16. Saprotrophs 5.1.3 Lives on or in non-living organic matter
Secretes digestive enzymes into the organic matter
Absorbs the products of the digestive process
Prokaryotes and fungi

17. Decomposers 5.1.14 Saprotrophic bacteria and fungi
Get nutrition from breaking down dead material
Examples include saprotrophic bacteria and fungi
Recycle nutrients by returning them to the environment in form of simple compounds such as carbon dioxide and nitrates (NO3), nitrites (NO2) ammonium (NH4)

18. Food Chain 5.1.4
Sequence of organisms each one feeds on the previous one
Arrows point in the direction of energy flow ie towards the organism that is doing the eating
Base of chain must be some form of autotroph
Following steps are consumers
No consumers feed on the last organism in the chain
Decomposers are not included

19. CO2
CO2

20. Length of food chains Generally 2 to 5 organisms long
Not longer because of inefficiency of conversion of energy from one organism to another

21. Trophic Levels 5.1.6
Categories reflect feeding relationships in food web or chain Producer, Primary Consumer, Secondary Consumer, Tertiary Consumer, Quaternary Consumer Carnivore, herbivore, omnivore – describe diet choices not trophic level – do not use them interchangeably

22. Food Web 5.1.5
Complex representation of feeding relationships within ecosystem more realistic than food chain Complex because most organisms feed on more than one species and are fed on by more than one species Some organisms feed at more than one trophic level Feeding preferences may change seasonally but are not shown in a food web

23. Because many animals eat more than one thing, tracing
Because many animals eat more than one thing, tracing energy through the estuary can get messy.
Relative Importance Of Food Web Linkages
Primary (75-100% of Total)
Secondary (50-74% of Total)
Tertiary (25-49% of Total)
Incidental (0-24% of Total)
Sanderlings,Long & Short-billed
Dowitchers, Greater Yellowlegs
Whimbrel, Mallard, Northern Shoveler, Pintail, Western Sandpiper
Great Blue
Heron
Snow Goose, Canada Goose, black Brant, American coot
Penpoint
Gunnel
Padded
Sculpin
Chum
Salmon (juv.)
Crescent
Gunnel
Bay
Pipefish
Pacific
Staghorn
Sculpin
Starry
Flounder (juv.)
Snake
Prickleback
Sharpnose
Sculpin
Saddleback
Gunnel
Tidepool
Sculpin
Shiner
Perch
Gastropod
Molluscs
Buffalo
Sculpin
English
Sole (juv.)
Nemerteans
Small Fish (inc.
herring, perch)
Bivalve
Molluscs
Cumaceans
Tubenose
Poacher
Polychaete
Annelids
Gammarid
Amphipods
Flabelliferan
Isopods
Tunicates
Gastropod
Molluscs
Silverspotted
Sculpin
Harpacticoid
Copepods
Mysids
Tanaids
Hippolytid,
Crangonid,
And Penaeid
Shrimp
Saltmarsh
Plants & Eelgrass
Brachyuran
Crabs
Benthic
Meiofauna
Valviferan
Isopods
Macrophytic
Algae
Phytoplankton
Microphytic
Algae
Anthozoans
Detritus
From Simenstad et al. 1979

24. Energy Required for Life
Metabolism – sum total of all chemical reactions occurring in living organisms.
Anabolic pathways – synthesize compounds, generally endergonic. (requires)
Catabolic pathways – break down compounds, usually exergonic. (produces)

25. There are many kinds of energy that can interconvert from one form to another.

26. Sunlight Source of Energy for Most 5.1.9
Most ecosystems are based on producers using sunlight – photosynthesis
Energy captured during photosynthesis is
stored in the chemical bonds of the
molecules synthesized during the process
Some use chemical compounds – chemiosynthesis

27. Incoming Energy
Many factors can affect amount of sun’s energy reaching the Earth’s surface
Absorbed or Reflected
Reflectivity of surface = albedo – can change with angle of light

28. Diagram of Earth's energy budget
Diagram of Earth's energy budget. Credit: Image courtesy NASA's ERBE (Earth Radiation Budget Experiment) program

29. In Ecosystems, Energy Flows and Matter Cycles 5.1.13
Primary energy source for almost every ecosystem is sunlight
Autotrophs convert radiant energy into chemical energy
Primary production is the creation of new organic material from inorganic materials
(Carbon dioxide and water yields sugar)

30. Energy Transfer
The stored chemical energy in the producer is available to the next trophic level
Energy is transferred from one organism to the next when the carbohydrates, lipids, or proteins are digested
If deer eats a clump of grass the energy goes to the deer if it dies without being grazed the decomposers will use the energy

31. Energy Use
Chemical energy used for cellular respiration into ATP by producers, consumers and decomposers
Organisms use energy for growth, reproduction, synthesis of molecules, cellular transport, movement
Assimilation = ingestion – excretion (including waste heat from cell respiration)

32. Not all transfers are equally efficient
Ectotherms (cold blooded organisms) have lower metabolic requirements than endotherms
80% assimilated energy used for metabolic needs
20% of assimilated energy for growth and reproduction
Herbivores assimilate less energy from food than carnivores (plants have lots of indigestible fiber material)

33. 1st Law Thermodynamics
Energy cannot be created nor destroyed by ordinary means only converted from one form to another

34. 2nd Law Thermodynamics
Energy transformations are never 100% efficient
Energy exchanges in a closed system the potential energy of the final state will be less than the potential energy of the initial state
Entropy increases in a system (entropy a measure of unavailable energy)
Disorder increases since energy is needed to maintain order to compensate for energy loss

35. Ecological Pyramids
The standing crop, productivity, number of organisms, etc. of an ecosystem can be conveniently depicted using “pyramids”, where the size of each compartment represents the amount of the item in each trophic level of a food chain.
Note that the complexities of the interactions in a food web are not shown in a pyramid; but, pyramids are often useful conceptual devices--they give one a sense of the overall form of the trophic structure of an ecosystem.
producers
herbivores
carnivores

36. Energy Pyramid
A pyramid of energy depicts the energy flow, or productivity, of each trophic level.
Due to the Laws of Thermodynamics, each higher level must be smaller than lower levels, due to loss of some energy as heat (via respiration) within each level.
producers
herbivores
carnivores

37. Energy flow units
How much moves from level to level and how quickly it moves
Trophic level energy units are for energy per unit area per unit time
Kilojoules per square meter per year
kJm-2yr-1
Energy = ability to do work so Joules is unit

38. Energy Losses Only chemical energy can be used at next trophic level
Only 10 to 20% of energy from an energy level is used by the next level

39. Why only 10% Not all parts eaten
Not all foods swallowed are absorbed (owl pellets) feces
Some organisms die without being eaten by organism at next level
Heat loss from cellular respiration

40. Number Pyramids
A pyramid of numbers indicates the number of individuals in each trophic level.
Since the size of individuals may vary widely and may not indicate the productivity of that individual, pyramids of numbers say little or nothing about the amount of energy moving through the ecosystem.
# of producers
# of herbivores
# of carnivores

41. Biomass Pyramid
A pyramid of standing crop indicates how much biomass is present in each trophic level at any one time.
As for pyramids of numbers, a pyramid of standing crop may not well reflect the flow of energy through the system, due to different sizes and growth rates of organisms.
biomass of producers
biomass of herbivores
biomass of carnivores
(at one point in time)

42. Inverted Pyramids
A pyramid of standing crop (or of numbers) may be inverted, i.e., a higher trophic level may have a larger standing crop than a lower trophic level.
This can occur if the lower trophic level has a high rate of turnover of small individuals (and high rate of productivity), such that the First and Second Laws of Thermodynamics are not violated.
biomass of producers
biomass of herbivores
biomass of carnivores
(at one point in time)

43. Points to remember
Note that pyramids of energy can never be inverted, since this would violate the laws of thermodynamics.
Pyramids of standing crop (biomass) and numbers can be inverted, since the amount of organisms at any one time does not indicate the amount of energy flowing through the system.
For instance think about the amount of food you eat in a year compared to the amount on hand in your pantry.