The Living World: Ecosystems (Chapter 10)

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The Living WorldEcosystems (Chapter 10)
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Ecosystem A community of living organisms
interacting with one another and with the
nonliving components of the environment they
inhabit.
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Levels of Ecological Organization
Level 1 Individual ( A Moose)
Level 2 Population (Herd of Moose)
Level 3 Community (Herd Birds Squirrels etc
Level 4 Ecosystem Living nonliving components in the environment
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Examples of Ecosystems

• Forest
• Lake
• Aquarium
• Island

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Interactions within Ecosystems
1 .1

• Trophic Relationships The feeding connections
  among the living organisms in an ecosystem (a
  food chain)

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Simple food chain
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More realistic food web
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Producers autotrophic (self nourish) organisms
with the ability to create organic matter from
inorganic matter in an ecosystem through
photosynthesis. Plants use sunlight to make
sugars for energy.
Plants
Phytoplankton (algae)
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Inorganic vs. organic matter
Inorganic matter Matter that is not necessarily produced by living organisms. (e.g. Water, mineral salts, carbon dioxide)
Organic matter Matter that enters into the composition of living organisms and that is usually created by them. (e.g. proteins, carbohydrates, fats)
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Consumers heterotrophic (other nourishment)
organisms that feed on other living organisms
and/or their products such as eggs, fruit etc.
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Consumers

• First order (or primary) consumers feed on
  producers (eg a deer eats grass, birds eat
  seeds). They are herbivores.
• Second order consumers feed on first order
  consumers (eg a wolf eats a deer, a cat eats a
  bird). They are carnivores.
• Third order consumers feed on second order
  consumers
• Fourth order consumers feed on third order
  consumers etc. etc.

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Omnivores

• Consumers that eat several orders at once. (eg
  bears eat berries and fish, humans eat grain and
  meat).

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Decomposers organisms that feed on the waste
and remains of other living organisms.

• Decomposers are detritivores which are
  heterotrophs that can be eaten by consumers
• Feed on detritus which is dead organic matter
  such as fallen leaves, dead wood, animal remains,
  etc

• Examples are
• worms, some bacteria, certain insects such as
  the sow bug

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Trophic Network Food Web
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Ecosystem Dynamics
1 .2

• Material and Energy Flow the exchange of matter
  and energy between the living organisms in an
  ecosystem and between those organisms and their
  environment.
• Law of conservation of Mass
• nothing is loss and
• nothing is created
• Matter is transformed

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Material Flow and Chemical Recycling

• Chemical recycling is a natural phenomenon by
  which decomposers make inorganic matter available
  in an ecosystem by breaking down organic matter.

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Chemical Recycling
Decomposers
Detritus
Consumers
Producers
Flow of inorganic matter
Environment
Flow of organic matter
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Energy Flow the sun is the main source of energy
for ecosystems
Thermal energy lost in the environment
Radiation energy
Secondary Consumer
Primary Consumer
Producer
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Biomass and Primary Productivity in Ecosystems
1 .3

• Biomass the total mass of organic matter in an
  ecosystem at any given time.

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• Primary productivity of an ecosystem is the
  amount of new biomass generated by its producers
• Factors that affect primary productivity are
• Light (radiation energy) from the sun
• Amount of water (necessary for photosynthesis)
• Essential nutrients (carbon, nitrogen,
  phosphorus, and potassium)
• Temperature weather promotes growth of
  producers

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Disturbances
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• A disturbance is an event that damages an
  ecosystem. It can lead to the elimination of
  organisms and alter the availability of
  resources.
• E.g. flooding, storms, oil spills, volcanic
  eruptions

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Natural Disturbances
2.1

• Events triggered by environmental phenomena
  rather than humans but can be very damaging
  nonetheless. (storm churning waters surface
  subsurface waters to mix)
• E.g. volcanic eruptions, drought, flood, forest
  fires, frost, freeze rain heat waves

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2.2
Human Disturbances
Humans and their actions are a major threat to
ecosystems from individual acts like littering to
large scale projects. E.g. logging, mining, oil
spills, housing projects, industries,
pollution, etc.
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Ecological Succession
2.3

• Ecological succession the series of changes
  that occur in an ecosystem after a disturbance
  and that continue until the balance of the
  ecosystem is restored.

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A forest recovering after acid rain
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Ecological Footprints
2.4

• Ecological footprints are estimates of the
  surface area individual humans or populations
  require to obtain the resources for satisfying
  all their needs and to ensure the disposal of
  their waste.

Land water used to produce goods
Land water used to dispose of waste
Ecological Footprint
Land water occupied



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Ecological Carrying Capacity
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• Ecotoxicology is the study of the ecological
  consequences of polluting the environment
  with various substances and radiation, released
  by human activity.

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Contaminants is any type of substance or
radiation that is likely to cause harm to one or
more ecosystems.
3.1
Class of contaminants Examples
Inorganic Lead, arsenic, mercury, nitrogen oxides, phosphorus
Organic Insecticides, pesticides, benzene, polychlorinated biphenyls (PCBs)
Microbial Viruses and harmful bacteria
Radioactive Uranium, plutonium, radon
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Toxicity

• Toxicity of each contaminant depends of the
  following three factors
• Concentration more concentrated higher the risk
• Type of organism it comes in contact with
• Length of exposure

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• Toxicity threshold the level of concentration
  above which a contaminant causes one or more
  harmful effects in an organism
• LD50 indicator used to determine toxicity dose
  that is lethal to 50 of individuals

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Bioaccumulation and Bioconcentration of
Contaminants
3.2

• Bioaccumulation the tendency among certain
  contaminants to accumulate over time in the
  tissues of living organisms.

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• Bioconcentration a phenomenon by which the
  concentration of a contaminant in the tissues of
  living organisms tends to increase with each
  trophic level.

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Biotechnology
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• Biodegradation the breaking down of organic
  matter into inorganic matter by microorganisms

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• Bioremediation a biotechnology for cleaning up
  a polluted site, using microorganisms that
  decompose the contaminants.

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• Phytoremediation a biotechnology that uses
  plants or algae to eliminate contaminants from a
  site.

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Wastewater Treatment

• Wastewater water that is discharged after
  household or industrial use and that is polluted
  as a result of human activities.
• Wastewater can contain
• Sand or other particles
• Pathogens
• Nutrients that stimulate the excessive growth of
  algae
• Chemicals

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• Two main methods for treating wastewater are
• Septic Tanks and Wastewater Treatment plants

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Checkup

• Pg 342 1-15, A and C ST and AST
• Pg 342 1-26, A - C EST
• Pg 342 18-23, B SE
• Eco-sketch Complex Task (ST AST)
• Pg 323 Vermicomposting from cafeteria (optional)

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References

• Observatory the Environment Cyr, Forget,
  Verreault 2009, ERPI
• Google Images