the living world: ecosystems (chapter 10). ecosystem – a community of living organisms interacting...
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The Living World:Ecosystems (Chapter 10)
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 OrganizationLevel 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
Examples of Ecosystems:
Forest
Lake
Aquarium
Island
Interactions within EcosystemsTrophic Relationships The feeding
connections among the living organisms in an ecosystem (a food chain)
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Simple food “chain”
More realistic food “web”
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)
Inorganic vs. organic matterInorganic
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)
Consumers – heterotrophic (other nourishment) organisms that feed on other living organisms and/or their products such as eggs, fruit etc.
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.
Omnivores:
Consumers that eat several orders at once. (eg: bears eat berries and fish, humans eat grain and meat).
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
Trophic Network – Food Web
Ecosystem Dynamics
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.
Chemical Recycling
Decomposers Detritus
Consumers
Producers
EnvironmentFlow of inorganic matter
Flow of organic matter
Energy Flow: the sun is the main source of energy for ecosystems
Producer
Thermal energy lost in the environment
Radiation energy
Secondary
Consumer
Primary
Consumer
Biomass and Primary Productivity in Ecosystems
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
DisturbancesA 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 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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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.
2.2
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Ecological Succession
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.
2.3
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A forest recovering after acid rain
Ecological Footprints
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.
2.4
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Ecological
Footprint
Land & water
occupied
Land & water used to produce
goods
Land & water used to dispose of waste
= ++
Ecological Carrying Capacity
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World Canada Japan China
Ecological Footprints
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.
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Class of contaminants
Examples
InorganicLead, arsenic, mercury, nitrogen oxides, phosphorus
OrganicInsecticides, pesticides, benzene,
polychlorinated biphenyls (PCBs)
Microbial Viruses and harmful bacteria
Radioactive Uranium, plutonium, radon
ToxicityToxicity 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
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
Bioaccumulation and Bioconcentration of Contaminants
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.
Biotechnology
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.
Phytoremediation – a biotechnology that uses plants or algae to eliminate contaminants from a site.
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
Two main methods for treating wastewater are:
Septic Tanks and Wastewater Treatment plants
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)
References
Observatory the Environment – Cyr, Forget, Verreault – 2009, ERPI
Google Images