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

2.1

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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

EST

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

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